History of the M6

M6 The North West Region of England, EXECUTIVE SUMMARY, By Harry L Yeadon BscTech FREng FICE FIHT

The building of a motorway is sculpture on an exciting and grand scale, carving, moding, forging and adapting the materials provided by nature earth, rock and minerals into a finished product, which must be functional and pleasing to the eye, as well as economical and durable. But in trying to accomplish this, one must be humanitarian and remember that all this affects people. The civil engineer on motorway projects, as on other public works, is the servant of the people, using his specialist knowledge on their behalf for the good of the whole community and, at the same time, mindful of their views and the rights of the minority who are affected

Drake

TABLE OF CONTENTS

1 GENERAL INTRODUCTION

2 CHARACTERISTRICS OF THE REGION

2.1 TOPOGRAPHY

2.2 GEOLOGY

3 THE ORIGINS OF THE MOTORWAYS OF THE REGION

3.1 THE EARLY YEARS

3.2 PLANNING FOR THE FUTURE IN THE POST-WAR PERIOD

4 THE NORTH-SOUTH MOTORWAY

4.1 PRESTON BY-PASS

4.2 THE LANCASTER BY-PASS SECTION OF M6 AND THE CARNFORTH LINK ROADS A601 (M)

4.3 THE WARRINGTON TO PRESTON SECTION OF M6

4.4 THE M6 IN CHESHIRE

4.5 THE PRESTON-LANCASTER SECTION OF M6

4.6 PENRITH BY-PASS

4.7 THE M6 THROUGH WESTMORLAND

4.8 CARLISLE BY-PASS AND THE PENRITH-CARLISLE SECTIONS OF M6

1 GENERAL INTRODUCTION

1.1 The Summary is based on a series of mini-archives, each covering a section of motorway within the Region. They are deposited in the County Record Offices at Chester, Preston, Kendal and Carlisle and contain -

i. written material prepared by a number of those personnel who were directly involved in the development of the motorway network

ii. various documents and

iii. lists of other relevant documents held in establishments elsewhere

1.2 The Counties within the Region, as referred to in the Summary, are the historic geographical Counties of Cheshire, Cumberland, Lancashire and Westmorland.

1.3 Chapters 4 to 18, describe the various motorways within the Region. They are listed broadly in the order in which the construction of each motorway first began. Where the work was carried out in distinct sections, these also follow in chronological order.

1.3.1 The description in each case includes:

i. a brief history

ii. the name of the organisation which undertook the design and supervision of construction, viz County Council, Sub-Unit of the North Western Road Construction Unit, firm of Consulting Engineers, or British Rail

iii. the basic facts, eg length, number of bridges

iv. matters of particular significance in its design and construction

1.3.2 The amount of space allocated to each motorway does not necessarily reflect the magnitude of the work involved, or its importance in the development of the network.

1.3.3 In most cases, the Tender figure for each Contract can be found in the Opening Brochure, or other documentation deposited in the relevant Records Office. No attempt has been made to identify the total cost of each section of motorway, which would not only include the amount of the final payment to the Contractors, but also ex-Contract items such as the expenditure on land acquisition and compensation, design and supervision, and the diversion of mains and services. Even it all this information was readily available, it would not be appropriate to make cost comparisons, due to the effect of inflation during the period of over 40 years of motorway construction, within the Region.

1.3.4 The list of References given at the end of each Chapter relates only to specific documents mentioned in the text, which a reader of the Summary may wish to consult initially.

1.4 The construction of the network was carried out by a large number of different firms of Contractors and Sub-Contractors. They are too numerous for all to be mentioned in the Summary, but the Principal Main Contractors are listed in an Appendix. Information on the various Contracts can be found in Opening Brochures, where these are available.

2 CHARACTERISTICS OF THE REGION

2.1 TOPOGRAPHY

2.1.1 The Region is an area of enormous variety. The plains of Cheshire and Lancashire are bounded by the Welsh hills and the Irish Sea to the West, and the foothills of the Pennines to the East. In the North the Cumbrian mountains provide a massive barrier to any form of communication in that direction.

2.1.2 Several large rivers flow through the Region. The Dee, Mersey, Ribble and Lune discharge into the Irish Sea and the Eden into the Solway Firth at the Scottish Border. Bridging, at suitable crossing places, was the main reason for the development of the ancient cities and towns of Chester, Warrington, Preston, Lancaster and Carlisle, which became the focal points for early transport systems.

2.1.3 The Industrial Revolution had its roots in the Region. This mainly arose from the exploitation of the coalfields of Lancashire and the West coast of Cumberland, and the availability of ample supplies of water resulting in major changes in economic activity within a substantial part of the area. A century or more of growth in textile manufacturing in the valleys of East Lancashire, in other industries such as engineering, in shipbuilding at Barrow, and in the production of chemicals in North Cheshire arising from the huge deposits of salt, led to the expansion of many other towns and cities.

2.1.4 Of major significance, Manchester became a substantial commercial centre particularly for the textile trade, and the focus of a large conurbation. The Port of Liverpool had been recognised for many years as an essential element in the life of the Region and, although road and rail connections between the two cities already existed, the Manchester Ship Canal was constructed at the end of the 19th century. Historically, the industry located around the mouth of the Mersey had been mainly associated with shipping and ship building but, later, the Ship Canal provided access for tankers to North Cheshire and enabled the construction of oil refineries and the manufacture of petrochemicals.

2.1.5 The coal measures of Lancashire did not extend beyond the Calder Valley and,therefore,little heavy industry existed in the northern part of the Region apart from on the West coast of Cumberland. Agriculture, however continued to be of considerable importance not only on the highly productive arable and dairy-farming land of Cheshire, West Lancashire and the river valleys, but also from stock rearing on the hill farms.

2.1.6 At the end of the Second World War, with a population of over 7 million living in a Region which was so complex both in physical, economic and social terms, there was general recognition that an adequate transportation system was of vital importance to its future prosperity. This was of special significance to an area suffering from the decline of mining, shipbuilding and textiles as new industries, such as those associated with aircraft manufacture and electronics, moved in. Their success is, to a large degree, dependent on the provision of improved links, particularly for those located in the less accessible areas, such as West Cumbria.

2.1.7 The growth in tourism has been of major economic benefit, arising from the increase in the number of visitors from outside the Region. The longstanding attraction of places such as the major seaside resort of Blackpool, and the Lake District have, for many years, had a great influence on traffic. It has been estimated that, in addition to the regular influx of day visitors to the National Park, the resident population may be exceeded threefold by those who stay for an extended period.

2.1.8 As in the rest of the Country, the Regions road system, prior to the construction of the motorways, was predominantly the legacy of past centuries. Its development had been largely fortuitous and lacking in strategic purpose. The only exceptions, were the provision of a number of local by-passes and the construction of the East Lancashire Road connecting Liverpool and Manchester, which was opened in 1934 the only major new road in the Region since the turnpike era!

2.2 GEOLOGY

2.2.1 The proposals for the line of a North-South motorway through Cumberland and Westmorland were confined to a corridor lying to the East of the Lake District massif. A description of the geology of those Counties is, therefore limited to that area.

2.2.2 The predominant Boulder Clay which exists in relatively shallow surface deposits and in drumlins has a wide range of moisture content, between 5% and 25%, and a varying silt, sand, gravel and boulder content.

2.2.3 In the Carlisle area there are deposits of sand and silt overlying bunter Sandstone, and alluvium with sand lenses in the valleys of Rivers Eden and Peteril.

2.2.4 North of Penrith, troughs of peat up to 20 feet in depth are found and in the area there is a volcanic intrusion known as the Armathwaite Dyke.

2.2.5 Further south the bed-rocks are closely jointed partially metamorphosed Silurian Siltstones and Mudstones and elsewhere the more recent Carboniferous deposits are encountered with the limestone containing numerous solution cavities.

2.2.6 In Lancashire, there are also Carboniferous rocks such as limestone, Millstone Grit and Coal Measures in the Pennines and in other high ground such as in the Forests of Bowland, Pendle and Rossendale.

2.2.7 The Carboniferous limestone outcrops in the area around Carnforth and, further south at Clitheroe, in the Ribble Valley This relatively massive limestone can be seen in numerous quarries in both areas. Elsewhere, it is overlain by the strongly-bedded shales, sandstones and gritstones of the Millstone Grit series

2.2.8 The Coal Measures, which overlie the millstone grit over a roughly triangular area to the south of the County centred on Wigan, Burnley and Oldham, are further sub-divided into lower, middle and upper, with the quantity and quality of the coal tending to improve at greater depth. The seams occur in repeating sequences of mudstones, shales and sandstones, and old shallow workings have been frequently encountered.

2.2.9 Younger permo-triassic rocks cover the Carboniferous rocks on the low-lying Lancashire Plain, but there is generally a good cover of drift and there are few outcrops to be seen. The Sherwood/Bunter Sandstone and the Keuper Marl are relatively soft rocks, characterised by a red colour, and the underlying coal seams have been worked in some places by deep mining techniques.

2.2.10 The drift deposits are mainly glacial in origin and are thought to be the product of a glaciation between 2000 and 12000 years ago. The most extensive cover the Fylde, south-west Lancashire and the Mersey embayment as far inland as Manchester, and have been derived from Triassic rocks on the bed of the Irish Sea. Very stoney till from the Lake District was deposited in the northern part of the County and some has intermingled with the Irish Sea drift, extending as far south as the Fylde. On the higher ground to the East, the local Pennine drift contains sandstone and shale fragments, sometimes indistinguishable from the metlwater derived head deposition on the steeper slopes.

2.2.11 In many places, there is a tripartite sequence of drift, with a heavily overconsolidated boulder clay overlying the bedrock. The overconsolidation pressure suggests thicknesses of glacial ice of the order of 250 metres. This Lower Boulder Clay is overlain by Middle Sands, glacial deposits of mainly fine to medium sand, with occasional inclusions of silt and clay, followed by Upper Boulder Clay.

2.2.12 The interglacial period responsible for the Middle Sands also produced locally important fluvio-glacial sand and gravel deposits in the vicinity of Carnforth, and to the North of Manchester in the Middleton/Heywood area. Several deep glacial channels have been recorded in the underlying bedrock, some extending well below present sea level. These channels are often associated with, but not always coincident with, todays rivers and are filled with relatively poorly-consolidated sand, clays and silts.

2.2.13 Lancustrine varved clays were deposited in ice-dammed glacial lakes in the Rossendale and Calder valleys. When the ice dams broke, the rapid draw-down of the water level destablised the clay on the steeper slopes and landslips were a frequent occurrence. The slipped masses are often still recognisable from their upper scarp slopes and bulging toes, but are sometimes obscured by later deposits.

2.2.14 Post-glacial deposits include raised-beaches and blown sands resulting from the retreat of the ice and the sea, and also alluvium in river valleys and estuaries.

2.2.15 Peat deposits are of several basic types, extensive and sometimes deep basin peats, such as at Chat Moss, raised mosses on the poorly-drained till plains in the south and south-east of the County, and thin climatic peat on the plateau areas of the Forests of Rossendale, Bowland and Pendle.

2.2.16 In Cheshire, the western half of the County is generally flat and low lying forming a plain which stretches from the River Dee to Congleton, where the ground rises to meet the Peak District and Pennines. The plain is broken bh the Mid-Cheshire ridge, which extends south from Frodsham towards Malpas. The ridge is intermittent and continues north, though less pronounced, into the Wirral peninsula.

2.2.17 The majority of the solid rock on the plain is obscured by thick glacial deposits left after the advance and retreat of the (Irish Sea) ice sheet. Much of the obscured bedrock is of Triassic age with older Carboniferous rocks exposed to the east of the County around Macclesfield. Tectonic movements have folded the rocks into a basinal structure with generally shallow angles of dip.

2.2.18 To the east of the County the Red Rock Fault, extends south past Congleton and north towards Macclesfield and brings the weaker Triassic Bollin Mudstone formation formerly known as Lower Keuper Marl against the more resistant Carboniferous and marks the edge of the lowland plain. The Carboniferous rocks are of the Millstone Grit Group and are present as shales and more resistant sandstones and gritstones. Coal Measures outcrop only in the northeast of the County near Macclesfield.

2.2.19 The bedrock over the majority of the plain belongs to the Mercia Mudstone Group formerly known as Keuper Marl, a weak rock often eroded and weathered by the ice to form the characteristic red brown glacial till deposits which blankets much of the County. More resistant beds within the Triassic sequence are the Tarporley Siltstone formation formerly known as Keuper Waterstones and the Helsby Sandstone Formation formerly known as Keuper Sandstone which forms outcrops mainly on the ridges, around Peckforton, Beeston, and Delamere. These sandstones are of considerable thickness and are locally important aquifers.

2.2.20 The famous salt beds, the Keuper Saliferous beds now known as Northwich and Wilkesley Halite Formations, are present nearer the middle of the County, notably around Tatton, north east of Lymm, Middlewich, Northwich and Winsford. The topography of the salt bearing areas is marked with subsidence features often infilled with water to form flashes or lakes.
2.2.21 The retreat of the ice sheet left extensive sand and gravel deposits over the County as well as deeply cut channels where the melt waters broke through their temporary dams such as the Deva spillway just north of Chester. Some of the more extensive fluvioglacial sand and gravel deposits are located around Chelford, extending from Rudheath to Gawsworth and as far north as Knutsford and south to Sandbach; and from Sandiway south to Little Budworth. Some of the sands are thought to represent multiple glacial advances and were formerly described with the glacial clays as the tripartite sequence formed of the Lower Boulder Clay, Middle Sands and Upper Boulder Clay. These Middle Sands are present around Congleton where they are quarried. Current thinking is that the glacial deposits represent only the final glacial episode with perhaps relics of previous glacial events surviving only in hollows, and that the complexity of the deposits is caused by progressive melt-out, pockets of stagnant ice, ponding of water and complex drainage relationships.

2.2.22 The main rivers draining the County to-day, comprise the Mersey, Dane, Weaver, Gowy and Dee. The rivers are associated with alluvial deposits and often river terraces formed of gravels. The largest of these rivers are the Dee, and the Mersey both set in extensive alluvial flood plains, which have meandering form. The river Dee runs almost north close to the western edge of the County to Chester, before feeding into a straightened channel through the salt marshes and alluvium and ultimately in to the Dee Estuary. Also of importance is the River Gowy, which rises on the mid-Cheshire ridge and drains northwest towards Frodsham Marsh and Ellesmere Port before discharging into the Mersey estuary. Although this is now a relatively small river, it is associated with considerable thicknesses of peat, which lie between Bridge Trafford and Thornton le Moors.

2.2.23 The Region, with its very strong association with the Industrial Revolution has, as would be expected, many areas which have been extensively modified as a consequence, and contains colliery, quarry and chemical waste heaps, as well as household waste disposal sites adjacent to the urban concentrations.

3 THE ORIGINS OF THE MOTORWAYS OF THE REGION

3.1 THE EARLY YEARS

3.1.1 Although not the first consideration given to the possibility of constructing motorways in Britain, in 1936 the Institution of Highway Engineers published a plan for a network of such roads.

3.1.2 A few years earlier, the Lancashire County Council had reached conclusions on proposals for improving the A6/A49 existing North-South route through the County. It was the intention to provide a high-standard all-purpose road of dual carriageways, cycle tracks and footpaths within an overall width of 120 feet.

3.1.3 However, in 1937, the County Council had become seriously perturbed by the number of accidents, both fatal and otherwise, on the Liverpool-East Lancashire Road which had been opened by King George V only as recently as July 1934. As an all-purpose road with an overall width of 120 feet, it had a single three-lane carriageway 40 feet wide and a very large number of surface level access points, which was the main reason for the high accident rate. Frequent requests were being received for some form of control to be installed at the various crossings, but it was felt that this would tend to reduce the efficiency of the road and would ultimately defeat the object for which it had been constructed.

3.1.4 The County Council expressed the view, therefore, that with regard to the earlier proposals for the North-South route, these evils should not be perpetuated. Taking this factor into account, and the extensive property demolition which would have been involved in improving the existing A6/A49 route, it was decided that an entirely new route with controlled access, was required. Further, that it should be restricted to the use of motor traffic, ie a motorway and, in that respect the proposal was in conformity with the plan of the Institution of Highway Engineers.

3.1.5 The most significant factor, however, in generating widespread interest in motorways during that period, was undoubtedly the development of the German autobahnen. Also in 1937, a Group known as the German Roads Delegation, numbering 224 members, including Members of Parliament, representatives of highway authorities, highway engineers and others involved in vehicle operation carried out a tour of inspection of the system.

3.1.6 James Drake, the newly appointed Surveyor of Blackpool, was a member of the Group and he was so impressed with what he saw, that he later recommended that a ring road, which had been proposed for the busy seaside resort, should be constructed as a motorway.

3.1.7 Meanwhile. the report of the Groups visit was considered by the County Surveyors Society and this led to the publication, in 1938, of its own plan for 1000 miles of motorway linking the main industrial centres in the Country.

3.1.8 Although only drawn to a small scale, both of those pre-War plans included a proposed motorway from London to Carlisle, passing through Cheshire, Lancashire, Westmorland and Cumberland. In South Lancashire, however, the 1936 plan showed an alignment through the Manchester area whereas the route in the later plan, as proposed by the then County Surveyor and Bridgemaster was sited further to the west, near Warrington.

3.1.9 The Minister of Transport at that time, the Rt Hon Leslie Burgin, also visited the autobahnen and recommended that, as an experiment, approval should be given to a scheme put forward by Lancashire County Council for the construction of a motorway 62 miles long, passing through the County between Warrington and Carnforth. Wigan was to be by-passed on the Western side, and Preston and Lancaster to the East. Some preliminary survey work was undertaken but the start of the War prevented any further progress.

3.1.10 Even during the period of hostilities, interest in the post-War development of a system of motorways continued, particularly within the other professional bodies such as the Institution of Civil Engineers and the Institution of Municipal and County Engineers.

3.1.11 The County Surveyors elsewhere in the Region were also actively involved in considering proposals for a North-South motorway.

3.1.12 In 1942, the County Surveyor of Cheshire produced an estimate for the cost of the construction of the section through his County amounting to 2.01m. Land was valued at 60 per acre, roadworks at 40000 per mile, and bridges at 11500 to 20000 each. He was also involved in discussions with the Ministry of Transport on the proposed standards of layout.

3.1.13 The origin of the scheme in Westmorland and Cumberland stemmed from the initiative taken by the County Surveyors Society, endemic traffic congestion in Kendal, Penrith and Carlisle, and the need to provide an all-weather route avoiding Shap Fell, where the A6 was frequently blocked during the Winter.

3.1.14 The drafting of a Bill to provide the necessary legislation for the construction of motorways began in 1945. While defining the basic principles underlying the provision of such roads, eg restricted access and a dual carriageway layout, design standards were proposed by Major H.E.Aldington, then Chief Engineer in the Ministry of War Transport, which included the following:-

Design speed	75mph
Formation Width	For dual two-lane carriageways: 93 ftFor dual three-lane carriageways: 109 ft
Marginal strip	1 ft wide at each side of the carriageway,flush with it and of a contrasting colour
Carriageways	Dual two-lane: each 22ft wide, excludingThe marginal strips.Dual three-lane: each 30ft wide, excludingThe marginal strips.
Verges	Normally 15ft wide and clear of obstructions, but some planting of small trees and shrubs to be permitted. The width may be reduced to 5ft at bridges.
Centra lReservation	Not less than 15ft, with the width to be maintained at bridges.
Curves	Radius not less than 3000ft
Gradients	Normal maximum 1 in 30, but up to 1 in 20 to be permitted in some hilly country
Lay-bys	To be provided at intervals, to enable drivers to draw off the carriageway to rest or make minor repairs.
Roadside Facilities	No frontage access allowed, but areas to be provided for the supply of petrol, refreshment, and for Police purposes. Parking places to be provided off the highway, particularly at view-points.
Bridges	Modern designs with the forms of construction, and the materials, to be appropriate to the circumstances.
Pavement design and surfacing	Attention to foundations essential. All road surfaces should, as far as practicable, be non-skid.

3.2 PLANNING FOR THE FUTURE IN THE POST-WAR PERIOD

3.2.1 Since the end of the Second World War, the road network of the Region has seen changes incomparably greater in scale and impact than any which has gone before beside these developments, even the Roman roads and the turnpikes seem modest. As elsewhere in the Country, the motorway network and the huge growth in private and commercial traffic which is inextricably linked with it, have been the subject of much debate.

3.2.2 In 1945, Drake was appointed County Surveyor and Bridgemaster of Lancashire, a post he was to hold for twenty seven years. At that time, the emphasis was on planning for the future and, in 1947, the County Council accepted his suggestion that a road plan should be prepared.

3.2.3 The principal types of traffic movement were carefully analysed, ie that passing through the County on long distance journeys; cross-border movements to and from points within the County; and traffic movements within Lancashire itself. The results showed that, despite some improvements undertaken in the 1930s, the existing road network was quite unable to cope effectively with all these movements. It was also clear that the situation would deteriorate further, as the volume of traffic increased.

3.2.4 In order that the future road network should be as safe as possible, a major pioneering research programme was undertaken. By analysing the accidents which had occurred, a new understanding was obtained of how different layouts, traffic controls and other features affected the number and types of accident. Using this information, it was possible to forecast the accident savings which could be achieved, as an element in establishing the economic justification for any proposed scheme.

3.2.5 The Trunk, Class I and Class II roads had to bear the brunt of heavy through traffic and it was felt that their importance warranted a fairer system of funding than hitherto. Lancashire, with its heavy industries and popular holiday resorts, had to cater for a weight of traffic quite out of proportion to the mileage of its main road system. It was, therefore, contended that resources should be allocated according to population as well as road mileage.

3.2.6 A great deal of traffic data was collected from which projections of future traffic flows and road capacities were made. This enabled the future network to be defined on a basis of three categories of traffic route of which the 1st Group comprised twelve express routes with dual carriageways, totalling 217 miles in length. Ninety-four miles were to be of motorway standard and all these routes were chosen to attract the highest volumes of traffic.

3.2.7 They included the North-South motorway and the Liverpool-Manchester-Yorkshire route, both of which had been included in a ten-year construction programme of national routes announced by the Minister of Transport, in 1946. The latter route was to incorporate the existing Liverpool-East Lancashire Road, as far as Worsley and then be a motorway following a line through the northern part of the Manchester conurbation through to the Yorkshire boundary.

3.2.8 Also within this category, it was proposed that the western section of the Manchester Outer Ring Road, crossing the Manchester Ship Canal by a high-level bridge, should be constructed as a motorway.

3.2.9 The function of the 2nd Group was defined as connecting large towns to a 1st Group route or to each other, and serving as important links. It was proposed that links from the North-South route to Blackpool and to Morecambe should be constructed as motorways, with a total mileage of 17.

3.2.10 In 1949, the Road Plan for Lancashire was approved by the County Council and the various proposals were included in the County Development Plan, which enabled future land use to be controlled. This allowed corridors of interest for the proposed new roads, including the motorways, to be protected against development, thereby making it much easier to achieve rapid progress in carrying out the necessary statutory procedures when schemes were eventually programmed.

3.2.11 In due course, the Development Plan was accepted by the Government of the day and therefore, in effect, the Road Plan received the general approval of the Ministry of Transport. However, because of the large financial commitment involved, the Ministry, not unexpectedly, did not endorse it in its entirety but the Plan proved to be of considerable importance. Not only did it form the basis of highway strategies within a major part of the Region for more than thirty years, but many of the processes which were developed in its preparation were subsequently adopted nationally.

3.2.12 The original Plan was. however, subject to continual review to take account of traffic growth and demographic changes, leading to the introduction of further motorway projects. By the end of the Century, there were twelve separately numbered motorways within the County.

3.2.13 In Cheshire, there was serious traffic congestion in places such as Chester, Frodsham, Stockton Heath, Tarporley and Knutsford. The River Mersey is the traditional boundary with Lancashire and together with the Manchester Ship Canal they have formed major transport barriers. The Ship Canal needs over 25 metres clear headroom for ocean-going vessels and the main road crossings were swing bridges which took at least ten minutes for each opening.

3.2.14 The County has a strategic location lying astride all north-south routes west of the Pennines. With industry in the north, good east-west communications linking Merseyside and the Manchester conurbation on the south side of the Canal have always been recognised as essential. However, road planning was not undertaken in isolation but was linked with plans for the surrounding counties and conurbations, notably, Lancashire, Staffordshire, Merseyside, Greater Manchester and Clwyd.

3.2.15 Its Development Plan of 1958 included a number of major road proposals. A road plan was prepared for internal use, but unlike the 1949 Road Plan for Lancashire, it was not published. However, in addition to the early design work for the M6 carried out by the County Council, several major studies were undertaken which were of major significance in the further development of the motorway network.

3.2.16 In 1965 the Blue Report established the case for the North Cheshire Motorway M56. Later, in 1968, a Report was prepared on the Proposed Major Road Network for the Chester Area, which referred to the urgent need to extend

3.2.17 the M56 west of Hapsford,

the M53 south of Hooton passing to the east of Chester and

joining the Southern Ring Road, and

the Ellesmere Port Motorway M531

3.2.18 Elsewhere in the Region, Manchester City Council had published a City Plan in 1945 which included a range of major projects for new roads. Subsequently, all the local authorities in the South East Lancashire and North East Cheshire (SELNEC) became involved in a major traffic survey, which resulted in the publication of a SELNEC Highway Plan, in 1962. It envisaged a large motorway and dual carriageway network, including a ring road of the City and various radial routes. However, apart from those motorways which had already been proposed by the Lancashire and Cheshire County Councils in their own plans, only a few of the others were to be constructed, for example, the Mancunian Way and the completion of the Outer Ring Road.

3.2.19 In Merseyside, a similar traffic survey was carried out, leading to the preparation of a 20 year plan for new roads, which was published in 1965. In due course, however, proposals for an inner ring motorway in Liverpool, with radial motorways, connecting to the national system, were to be abandoned. In consequence, the development of the motorway network in the area was to be confined to the construction of the Liverpool Outer Ring Road, M57, and the northern section of the Mid-Wirral Motorway, M53, connecting with the second Mersey Tunnel.

3.2.20 In the late 1960s major transportion studies were undertaken in the two conurbations. The results of the SELNEC Transportation Study and the Merseyside Area Land Use/Transportation Study (MALTS), and the subsequent decisions taken by the Authorities concerned, did not materially influence the planned development of the motorway network. 3.2.21 The preparation, design and construction of each section of motorway within the Region is summarised in the following Chapters.

THE NORTH-SOUTH MOTORWAY

4.1 PRESTON BY-PASS

4.1.1 In the mid-1940s, Drake had obtained the approval of Lancashire County Council to proceed with the preparation and preliminary design work for the North-South motorway through the County. It was found that the basic alignment, as envisaged in 1937, was still appropriate and only comparatively minor adjustments had to be made. It was realised, however, that economic factors made it impracticable to embark on the construction of the whole of the motorway as a single project. In 1952, therefore, consideration was given to the possibility of constructing those sections of the motorway by-passing Lancaster and Preston, in order to relieve the serious traffic congestion and reduce the number of accidents within those conurbations.

4.1.2 Encouraged by the preparatory work carried out by the County Council the Minister announced, in 1953, that the construction of the 8 mile Preston By-pass was to be included in his expanded road programme to commence in the 1956-57 financial year and that a start was to be made on the statutory procedures. 4.1.3 At the time, the Minister described the By-pass as a guinea pig in other words, as an experiment for all other British motorways. In view of its significance and the lessons which were learned in carrying it out, this particular project is referred to in much more detail in the Summary, than any other section of motorway.

4.1.4 The County Council was appointed the Ministers Agent Authority for the design and resolved to carry out the widest possible public consultations. Drake suggested that, rather than relying solely on drawings to illustrate the proposals, a large model should be constructed and, in order that the design programme should not be delayed, members of the staff keen to see the project proceeding, agreed to build the model in their own time. At subsequent public meetings which were held throughout the are, it proved to be of enormous value in explaining the scheme.

4.1.5 The route of the By-pass followed a line very close to the eastern edge of the built-up areas of Fulwood, Preston, Walton-le-Dale and Bamber Bridge, with only one farmhouse and three other dwellings directly affected. For many years, a corridor to provide for the future construction of the motorway had been 'protected'and, in several instances, post-War housing development within the urban areas had not been allowed to extend beyond its western boundary. Apart from terminal roundabout connections to the A6 at each end, there was to be only a single interchange junction with the A59 at Samlesbury, approximately half-way along its length.

4.1.6 Following the advertising of the proposals, only a few formal objections were received and these were resolved by agreement. The Minister was therefore able to confirm the various statutory Orders without a Public Inquiry. This was quite remarkable, in the light of the vociferous opposition to similar proposals which was generated elsewhere in the Country as motorway schemes became the subject of formalised and lengthy Public Inquiries, often disrupted by objectors not directly affected. Part of the explanation lies in the fact that there was close personal involvement of both the members of the County Council and the County Surveyor, in the consultation process. As a result, those affected had full confidence that their interests would be properly considered, both in the detailed design of the works and during construction.

4.1.7 It could be argued that, as there had been no previous experience of motorway construction in Britain, members of the public could not appreciate the full impact of the construction and the use of a road of such magnitude. If this had been so, those likely to be affected when other sections of the motorway came to be considered might have been inclined to raise strong objections. In the event, however, by adopting a similar approach, all the statutory procedures for the whole of the sixty-two miles of the M6 through the County were completed without difficulty.

4.1.8 Based on the experience of motorway construction and operation in Italy, Germany and the United States, various design principles had been established for use in Britain with several significant changes from those proposed in 1945, by the Chief Engineer in the Ministry of War Transport. The design speed was to be 70mph, although there was to be no speed limit when the motorway was opened to traffic. Instead of lay-bys, hard shoulders 8 feet wide were to be provided adjacent to the carriageways except at bridges, where the risk of a vehicle breaking down and blocking a traffic lane was considered to be minimal. With a verge only 4 feet wide at such locations, a considerable saving was achieved in the cost of the structures. The overall width was to be 112 feet with the two-lane carriageways each 24 feet wide and a central reservation of 32 feet, in which a hedge was to be planted as a screen against the effect of opposing headlights. The limiting gradient was to be 1 in 25.

4.1.9 Drake had recommended two important design features but the Ministry, which was financing the whole of the cost as a trunk road scheme, was not prepared to accept their introduction.

4.1.10 The proposal to provide a positive drainage system using conventional was not accepted and instead, it was decided that surface water run-off would be collected in stone-filled trenches, known as 'french drains', located either in the central reservation or behind the hard shoulders. This followed the practice adopted for the drainage of runways in the construction of airfields during the War.

4.1.11 On the basis of his own traffic predictions , Drake had argued that the carriageways should be constructed with three traffic lanes rather than with two lanes, which the Ministry considered to be adequate. However, a compromise was accepted whereby the overall width of the By-pass was to be increased, the bridges designed accordingly, and the central reservation made sufficiently wide to allow for the addition of a third lane to each carriageway at a later date. In due course, therefore, the carrying capacity could be increased with minimal disruption to traffic and without the need for structural alterations to bridges.

4.1.12 Lancashire had two main sources of materials for road construction. In the south of the County there were massive deposits of burnt red shale, which had been accumulated during many years of coal mining, while in the Clitheroe and Carnforth areas existing quarries produced high quality limestone aggregates, properly screened and graded to meet any specification. The form of carriageway construction was to be such that the maximum possible use would be made of mechanical plant and several pilot projects had been carried out on county roads in which a pre-mixed waterbound limestone macadam, to be known as wet mix, was developed as a material for the base.

4.1.13 At that time, it was common practice in the construction of new roads, particularly where major earthworks were involved, to defer the laying of the final surface until the carriageways had been subjected to traffic use. It was considered, therefore, that only a temporary surface should be laid, so that any early deformation could be remedied before completion, thereby ensuring a high standard of running surface over an extended period.

4.1.14 Taking all these factors into account, it was decided that the carriageway construction should consist of a sub-base of burnt red shale, varying in thickness from 12 to 36 inches depending on ground conditions, followed by a 9 inch thick layer of wet mix and a surface of 2 inch thick tarmacadam base course with a inch thick temporary wearing course of fine cold asphalt. The form of construction of the hard shoulders was to be little more than that of a hardened verge.

4.1.15 Twenty two bridges were required and great care was taken to ensure that each type was aesthetically suitable for the particular site. Designers were allowed a fairly free hand and there was a great deal of innovation with a preference for concrete construction employing differing prestressing systems. The use of concrete was also in recognition of the anticipated difficulties of providing access on a live motorway for the future maintenance painting of steel structures.

4.1.16 The design loading for highway bridges was set out in Memorandum 577 which required all bridges, with the exception of accommodation bridges, to be capable of carrying a specified uniformly distributed load, plus a knife-edge load representing the excess of the heavy axles over the other axles in the Standard Loading Train. In addition, bridges carrying motorways were required to be designed to carry 45 units of Abnormal Load which was simplified into two knife-edge loads of 15000lbs per foot, 10 feet long and 25 feet apart, with modifications for transverse members. For this loading, a permissable overstress of 25% was allowed.

4.1.17 In general, for spans up to about 50 feet, a desirable shallow construction depth was to be achieved using pretensioned prestressed beams placed side by side and infilled with concrete, but the Ministry required such decks to be transversely prestressed. There were no standard beam sections available, and as the beams were to be cast and stressed using the long-line system, much experimental design work was carried out.

4.1.18 In order to reduce the tunnel effect in instances where the motorway crossed a minor road, such that the span of the bridge was very much less than its width, light wells were to be provided within the central reservation.

4.1.19 For one particular single span bridge over the motorway, the deck was designed with beams 99 feet long to be cast on site and post-tensioned using the Magnel-Blaton system.

4.1.20 Another over-bridge was required to carry 30 inch and 24 inch water mains in the footways, and the depth of construction required to accommodate them determined a single span arrangement. Steel plate girders with the deck constructed in two halves enabled the mains to be temporarily diverted in turn in order to maintain full water supply to Preston, and avoid undue restrictions to traffic.

4.1.21 Two major bridges were required to carry the By-pass over the River Ribble and the A59 at Samlesbury, and across the valley of the River Darwen. In both cases, steel was the preferred form of construction for the superstructure.

4.1.22 At Samlesbury, various arrangements of spans were investigated, ie two, three, four and five spans. Following discussions with the Chief Bridge Engineer of the Ministry, Mr C.S.Chettoe, a three span continuous steel box girder structure with curved soffits was chosen. At that time, this form of construction was comparatively new. Three-inch long sections of rolled steel channel welded to the top of the eight girders as shear connectors to the reinforced concrete deck slab ensured composite action. The 420 feet long deck was to be supported on mass concrete abutments with wing walls and two mass concrete piers contained within permanent sheet pile cofferdams. A steel interlocking toothed expansion joint at the Southern end of the deck was to be concreted into the deck and the curtain wall of the abutment.

4.1.23 The six span 474 feet long Higher Walton Bridge was designed with a superstructure of welded steel plate girders and concrete deck, carried on reinforced concrete trestle piers.

4.1.24 Hot rolled asphalt was specified as the carriageway surfacing on the bridges and it was assumed that this would be impervious. However, a waterproof membrane was to be provided under the side verges and the central reserve.

4.1.25 It was decided that separate contracts should be entered into for each of the two major bridges. The major contract was for all the roadworks and nineteen other bridges. Tenders were invited by the County Council, early in 1956, and approval was given, by the Ministry, to the acceptance of the lowest bids, which enabled construction to commence in June of that year, with Drake appointed as Engineer for all the three contracts.

4.1.26 The provision of a bridge carrying the Preston-Longridge railway line over the motorway was to be undertaken by British Rail.

4.1.27 The two-year period for completion was based on the presumption that the weather would approximate to that of average summers and winters in Lancashire but, in the event, almost continuous rain fell from the start of the work.

4.1.28 In order to deal with the massive earth-moving programme, the principal Contractor had assembled a fleet of heavy plant which included tractors, scrapers, large capacity excavators and rear-dump trucks. However, the rains of the Autumn 1956 made it virtually impossible to work the sandy clay sub-soil and the major earthworks were postponed until the following Spring. Due to the exceptional circumstances, the Contractor was granted a five months extension of time.

4.1.29 Following a brief spell of fine weather early in the following year, there was a similar period of very heavy rain, and this situation was repeated in 1958. This caused the loss of large quantities of excavated material which, in normal weather conditions, would have been used for embankment construction. As a result, it had to be taken to tip and replaced by imported material.

4.1.30 The adverse weather did not materially affect the bridgeworks programmes. However, several issues of an unexpected nature arose during the period of construction.

4.1.31 The Contractors sought approval to the use of ready-mixed concrete from a plant which had been established recently some 15 miles from the site. At that time, the use of material provided in this way, was a new development in the area. Understandably, concern was expressed at the extent to which it would be possible to control the mixes, particularly, in regard to the water/cement ratio of the high strength concrete for use in prestressed elements of structures. Arrangements were made, therefore, for members of the supervisory staff to visit the plant when critical mixes were to be delivered. Not only were the materials inspected, but the moisture content of the aggregates was tested in order to ensure that the amount of added water was appropriate for the mix.

4.1.32 The conventional practice in the painting of steel bridges was to use a neutral colour, such as grey. Drake expressed the view that a variety of brighter colours should be introduced, for two reasons. Firstly, to enhance the appearance of the bridges and secondly, and perhaps more important, as a safety measure to ensure that drivers did not suffer from boredom while driving on the motorway.

4.1.33 In the early stages of painting Samlesbury Bridge, and before the surfacing had been laid on the deck, it was found that in one localised area, the paint had been stripped from the face of one of the outside girders. Tests showed that rainwater seeping through a minor defective area of the deck concrete had become highly alkaline with a PH value approaching that of caustic soda. Repairs were carried out and the painting was completed satisfactorily.

4.1.34 An examination of concrete used elsewhere in the project indicated that this was a common phenomenon. Enquiries directed at the cement suppliers established that the cause was due to inadequate burning during the manufacturing process, which arose from the high demand within the construction industry at that time. The problem was well-known in other countries, such as Denmark, where there was experience of corrosion of the steel in reinforced concrete structures. The advice which was received, was to the effect that, in most instances, the PH value of the leachate would reduce rapidly and further testing showed this to be the case.

4.1.35 The inner surfaces of the steel box girders of Samlesbury Bridge were to be painted, but it was considered that some means should be provided for measuring the humidity of the interior. A tap was, therefore, fitted on each of the access manhole covers to enable air samples to be extracted. It was found, however, that during periods of changeable weather the expansion and contraction of the air within, was so great that the girders could be heard to breathe. Meanwhile, consideration was being given to controlling the humidity by placing silica gel within the girders in order to reduce the frequency of maintenance painting. This form of treatment was found to be successful, by completely sealing the boxes with the fitting of air-tight gaskets to the covers and the removal of the taps.

4.1.36 In view of the innovative nature of the design of many of the bridges, arrangements were made for the Ministry to carry out the test-loading of several of the completed structures prior to the opening of the By-pass. The results were used in the development of future design standards.

4.1.37 Extensive landscaping was carried out, not only within the limits of the motorway but also on adjoining land acquired after negotiations with the owners, and in the areas where unsuitable excavated material had been tipped. This was followed by an extensive tree planting scheme and the provision of hedges along the boundaries and within the central reservation.

4.1.38 It had been decided that lighting was only needed at the Samlesbury Interchange and at the terminal roundabouts. Lighting schemes were designed in accordance with the appropriate standards in use at the time. However, towards the end of the construction period, when most of the lighting columns in the interchange had been erected, the Minister visited the site. On viewing the Interchange from the south escarpment of the Ribble valley, he expressed concern at the effect on the surroundings of the large number of columns in such a small area and immediately ordered their removal a further indication, even in those days, of the interest in minimising any adverse effect on the environment.

4.1.39 On 5th December 1958 the Preston By-pass, Britains first motorway, was opened to traffic. In view of the national importance of the event the ceremony was performed by the Prime Minister, Harold Macmillan, and a granite plinth marking the occasion was erected at the Samlesbury interchange.

4.1.40 In January 1959, however, a small amount of frost damage affecting the carriageways occurred as a result of an exceptionally rapid thaw, when the temperature rose from 8F to 43F within a period of thirty-six hours. Since there was no speed limit on the motorway it was decided that, for safety reasons, it should be temporarily closed to enable remedial action to be taken. This situation had arisen primarily because of the exceptionally wet weather during construction, which meant that there was still a high water table in the formation below the carriageways. As the hard shoulders were not paved and, therefore, were permeable, surface water run-off was able to drain directly into the formation, thereby exacerbating the problem. Furthermore, the burnt red shale used in the sub-base had not been screened or graded and, where it contained an excess of fine material, capillary action took place, drawing ground water to the surface. In the circumstances, the thin temporary surface of the carriageways proved to be inadequate to resist the effect of the freeze/thaw cycle when subjected to heavy traffic.

4.1.41 In view of the fact that there was no speed limit, it was decided, for safety reasons, that the motorway should be closed temporarily to enable repair work to be carried out. This led to much criticism, which failed to recognise that, under a financial regime requiring the maximum economy in design and construction of a type of road new to Britain, it was probably inevitable that problems would arise.

4.1.42 Because of the importance of food production, at that time. It was necessary to restrict the acquisition of agricultural land to the absolute minimum. Based on the original site investigation, it was considered that the cuttings could be formed with slopes as steep as 1 in 1 but, due to the nature of the material, surface slips occurred both during construction and after the motorway had been opened to traffic. The remedial work was both costly and disruptive.

4.1.43 Many other important lessons had been learned and it was considered vital that the experience gained in the preparation, design, construction and operation of this first section of motorway should be taken into account in carrying out future schemes. It was clear that attention needed to be given to a number of aspects, particularly in respect of the following:-

i. The extensive public consultation carried out throughout the whole process,had not only assisted in the smooth passage of the statutory procedures but also in dealing with complaints during the period of construction.

ii. In order to ensure that as much suitable excavated material as possible is used in the construction of embankments, the responsibilities of the Contractor in carrying out the earthworks should be more clearly defined in both the Specification and the Bill of Quantities. In that respect, it is incumbent on the Contractor to employ appropriate types of plant, having regard to the ground and weather conditions.

iii. Great care should be taken in the design of the slopes of cuttings and embankments, having regard to the characteristics of the materials involved.

iv. The carriageway sub-base material should be of properly screened and graded material complying with a clearly defined specification.

v. The surface-water drainage system was unsatisfactory,

vi. The principle of laying a temporary surface on the carriageways of motorways should not be perpetuated.

vii. It soon became evident that continuous hard shoulders would have been a valuable asset, a) as a means of access for emergency vehicles when a breakdown or accident occurred which brought traffic to a halt, and b) for use as additional traffic lanes when it was necessary to close the normal running lanes for maintenance purposes.

viii. The form of construction of the hard shoulders was inadequate, as it was not unknown in jacking-up a heavy vehicle, for the jack to be driven into the surface instead of lifting the vehicle.

ix. The explosive growth of traffic, which occurred within a short period after opening, demonstrated the need for all future motorways to be constructed with dual three-lane carriageways at the outset, unless there are very strong reasons to the contrary.

x. Irrespective of the type or surfacing, bridge decks should be fully waterproofed.

xi. Hedges are unsuitable for use as any form of barrier in the central reservation, particularly due to the effect on growth arising from winter gritting operations. In view of the liabilities of the Highway Authority for the maintenance of the motorway boundary fencing, doubts were expressed at the suitability of hedges for this purpose.

xii. Light-wells in the central reservation of underbridges are a potential hazard.

xiii. There was a favourable reaction to the use of different colours in the painting of steel bridges.

4.1.44 Following the frost damage to the carriageways, local repairs were carried out and immediate steps were taken to improve the drainage system. The final 4 inch thick hot-rolled asphalt surface was laid within 12 months, much earlier than originally intended. In 1963, the hard shoulders were reconstructed and paved, their distinctive red surface giving a contrasting colour as an aid to drivers.

4.1.45 A safety barrier was erected in the central reservation in replacement of the hedge and to prevent out-of-control vehicles crossing from the opposing carriageway.

4.1.46 After only eight years, traffic flows had increased to such an extent that it became necessary to add a third lane to each carriageway by reducing the width of the central reservation, as originally intended.

4.1.47 Following several failures during the construction of box girder bridges in Britain and abroad in the late 1960s, national concern was expressed at the adequacy of this type of design. Temporary lane closures were, therefore, applied to all such bridges until an independent check had been carried out. It is pleasing to note that Samlesbury Bridge was one of the few which did not require any strengthening.

4.1.48 Despite its problems, the construction of the By-pass undoubtably gave good value for money compared with later motorways designed and constructed to higher standards.

4.1.49 The Road Plan had included a proposal for a northern by-pass of Preston, to connect with the M6 at Broughton and provide a motorway to Blackpool and the Fylde Coast. In the early 1960's, representations were made to the Ministry of Transport for an early start to be made on its construction, and preliminary preparation and design work was carried out by the County Council. However, as a result of the general increase in traffic, particularly on M6, and with the prospect of further increases arising from the development of the Central Lancashire New Town, it was decided to undertake a Study of the need for improved East/West communications throughout the whole of the Preston area.

4.1.50 The Study Report, published in September 1969, concluded that, on the basis of predicted traffic flows, a full network of by-passes, to be known as the Preston Box, would be required by 1980. In addition to the Northern By-pass, which merited the highest priority, it was considered that both Southern and Western By-passes were necessary.

4.1.51 The preparation, design and construction of the Northern By-pass, subsequently numbered M55, is referred to elsewhere in this Summary. The crossing of the River Ribble by a Western By-pass subsequently became more viable by the closure of Preston Dock to large merchant vessels. By the early 1990s considerable progress, in terms of design and public consultation, had been made in respect of both the Southern and Western By-passes, which were then the responsibility of the Department of Transport (DTp).

4.1.52 Meanwhile, a Study carried out in 1984-86 drew attention to the need for the widening and improvement of the Preston By-pass Section of M6 between the junctions with the M61 (J30) and the M55 (J32).

4.1.53 In 1987 following several multiple fatal accidents, the DTp included the project in the Trunk Road programme contained in the White Paper Policy for Roads in England. Rendel Palmer and Tritton (RPT) were commissioned to appraise the situation, prepare an appropriate scheme and process it through to completion by acting as the Engineer for the Contract.

4.1.54 Although the whole length of the original Preston By-pass between Bamber Bridge (J29) and Broughton (J32) had been widened to three lanes in 1967, the hard shoulders had remained discontinuous at all the bridges. The number of lanes available, therefore, during maintenance operations, or when dealing with accidents, was inadequate to cope with the volume of traffic, up to a maximum of 140,000 vehicles a day.

4.1.55 The section between J30 and J32 is a common link for both East-West traffic (M61-M55) and North-South traffic (M6) and is particularly overloaded when tourist traffic to and from the Lake District and Blackpool coincide.

4.1.56 The DTp considered speed to be of the essence in preparing and carrying out the scheme and initial target dates proposed a start on site in 1991-92, but it was agreed that even an accelerated programme would take somewhat longer. In the event the following dates were achieved:

1989 Public Consultation and Exhibition,

1991 Public Inquiry,

1993 Main contract let in March

4.1.57 In July 1993, the Minister announced that further work on the Southern and Western By-passes would be deferred until traffic conditions on the widened section of the M6 could be assessed. However, it was decided that the route of the By-passes should be protected for planning purposes.

4.1.58 The approved scheme widened the M6 between J30 and J32 to a dual four- lane motorway and added extra lanes to both M6 and M61 at J30. Lighting, gantry signs and signals, CCTV and upgraded motorway communications were provided throughout.

4.1.59 Consideration was given, in the traffic studies, to the contiguous scheme for the Blackburn Southern By-pass section of the M65, joining south of J29, and the possible extension of it via the proposed Southern and Western By-passes.

4.1.60 It was decided that although dual four-lane carriageways might not, in later years, be always free from congestion, the recommendation of anything greater than this could not be justified.

4.1.61 The original DTp requirement was to maintain three lanes in one direction and two in the other, during construction. This was later increased to three in each direction and greatly influenced the design.

4.1.62 The options for widening a live motorway are,
Symmetrical where width is added on both sides

Asymmetrical where width is added on one side only and

Parallel where a new section of road is constructed off-line.

4.1.63 The approved scheme was a combination of all three options. From the M61 overbridge at J30, the widening was all to the west (Asymmetrical). The alignment came back to cross Samlesbury Bridge on line and then the widening swung across to the east (Asymmetrical), with a section of new carriageway off-line (Parallel) under Longridge Road before rejoining the existing alignment at J32.

4.1.64 The scheme required the demolition of all 11 overbridges, their replacement by eight new structures, and one underbridge. The four remaining underbridges were widened and strengthened.

4.1.65 During the design process the Commission for New Towns appointed RPT to examine the possibility of providing a new junction, (J31a), between J31 and J32 to give access to their proposed Preston East Employment Area. A half junction was eventually approved with south facing slip roads only, and the underbridge and stub slip roads were constructed as part of the M6 widening contract. The junction has since been completed and opened to traffic.

4.1.66 Ground conditions proved more difficult than expected and earthworks were suspended over one winter. This meant that the Contractors accelerated programme would not be achieved, but the dual four-lane carriageways came fully into use in August 1995.

4.1.67 Two bridges with discontinuous hard shoulders remain south of J30. These could be widened using M65 and M6 for traffic diversions.

4.1.68 The difficulties in carrying out the work were considerable. The Engineer, the Contractor and the Police exercised great skill in dealing with the traffic during the progress of the work but it was inevitable that serious disruption would occur, from time to time. This was reflected in the very high cost of the project and reinforces the view expressed at the outset that it would have been preferable, and more economic overall, to have embarked on the construction of the Southern and Western By-passes first, before carrying out the M6 widening.

4.2 THE LANCASTER BY-PASS SECTION OF M6 AND THE CARNFORTH LINK ROADS A601 (M)

4.2.1 The construction of the 11 mile Lancaster By-pass section of the M6, the County Councils second priority, had followed a year after the work on Preston By-pass had started. In many respects, it was similar, for example, it would also have dual two-lane carriageways with a wide central reservation for the future addition of third lanes.

4.2.2 Following extensive public consultation the statutory procedures had been completed without difficulty. It had been considered to be necessary, however, to move a section of the line at the southern end from that originally proposed in order to avoid a major objection, as it passed through land designated for the building of the future University of Lancaster. The effect was to take it through a wooded area which, no doubt in later years would have brought vociferous protests from environmentalists

4.2.3 By-passing the City of Lancaster on its eastern side, with connection to the A6 at each end, it was not the intention to provide an intermediate interchange as part of the project. However, the Road Plan for Lancashire had included a future proposal for a motorway link road to Morecambe and the port of Heysham, to connect with the By-pass by means of a two-level interchange at Halton, on the north side of the River Lune. It was accepted that this was unlikely to be constructed for many years and, therefore, serious concern was expressed at the difficulties likely to be experienced by the emergency services in gaining access to the By-pass.

4.2.4 The only road of any importance crossed by the By-pass is the A683, leading from Lancaster north-east-wards along the south side of the River Lune. The emergency services were based in the City and it was decided that a connection should be provided for their sole use, with the County Council agreeing to pay 25% of the cost. The design standards of this junction were lower than those of a normal interchange, with the carriageways of the slip roads separated only by double white lines. Subsequently, however, local representations were made for the junction to be opened for general use and this was eventually agreed. The result is a unique sub-standard interchange on a British motorway.

4.2.5 A total of 27 bridges was required. The major obstacle along the line of the By-pass was, however, the River Lune. The design chosen for the 400 foot long bridge at Halton incorporated a reinforced concrete open spandrel fixed arch with a clear span of 230 feet and a rise of 44 feet. Because of their width, bridges carrying motorways are normally designed as two structures separated by a narrow gap. In casting such a large arch, massive support is necessary and the Contractor built a temporary timber gantry across the river to carry the scaffold and shuttering for the first half. On completion, this was lowered slightly, winched sideways as a complete unit on to a second gantry, raised to the correct level and used to form the second arch. Users of the motorway are, unfortunately, unaware of this impressive bridge in such an attractive setting.

4.2.6 Work on the construction of the By-pass was well advanced before the problems experienced on Preston By-pass became apparent. In view of the close proximity of major limestone quarries in the Carnforth area at the northern end of the By-pass a sub-base of this material had already been specified, but it was only possible, at that late stage, to introduce a few of the other desirable design changes.

4.2.7 A positive drainage system was installed and the carriageway construction included the laying of a 4 thickness of hot rolled asphalt, as the permanent surface.

4.2.8 With difficult ground conditions similar to those experienced at Preston, and the bad weather during the same period, delays and disruption were inevitable, but the By-pass was opened (4) to traffic in April 1960.

4.2.9 At the northern end of the By-pass, at Carnforth, a one mile long link road provided the connection to the A6, and was subject to the motorway traffic regulations.

4.2.10 In due course, when the M6 was extended northwards a grade-separated roundabout interchange was constructed and the link road was designated A601 (M).

4.2.11 On the east side of the M6, large quarries had been worked for many years. The main access was via the B6254 which ran from the centre of Carnforth and crossed the M6 immediately south of the interchange.

4.2.12 In the late 1980s, a short single carriageway link road was built to connect the B6254 to the interchange roundabout, and this was also designated A601 (M). Quarry traffic was, therefore, provided with direct access to the M6, thus giving considerable relief to the town.

4.3 THE WARRINGTON TO PRESTON SECTION OF M6

4.3.1 In June 1958, while the Preston and Lancaster By-passes were under construction, the route of the 27 miles of motorway between Thelwall and Preston, bypassing Warrington on the east and Wigan on the west, was confirmed. Two major bridges were required the thirty-six span Thelwall Bridge (commonly known as the Thelwall Viaduct), over the Manchester Ship Canal and the River Mersey and the six-span Gathurst viaduct across the Douglas valley west of Wigan. Because of their size and complexity an early start on their construction was vital and work began in September 1959. This was one of the earliest examples of the system of advance works in motorway construction, a practice which became generally accepted as a means of dealing with particularly difficult obstacles.

4.3.2 Thelwall Viaduct is 4,414 feet long and rises to a height of 93 feet above the Ship Canal. It was of sufficient width to accommodate dual three-lane carriageways and a central reservation but, in order to reduce the cost of the structure, hard shoulders were not provided. This proved to be the cause of accidents when vehicular breakdowns blocked the running lanes and a source of serious traffic problems when lanes were closed during maintenance operations.

4.3.3 Ground conditions were particularly difficult, with soft alluvial deposits over the whole of the site. The land between the canal and the river had been used for the disposal of canal dredgings and was overlaid by a layer of silt some 45 feet deep. In consequence, the reinforced concrete piers, which varied in height from thirty to eighty feet, had to be carried on piles up to 130 feet in length, to provide a satisfactory foundation. The superstructure consists of steel plate girders supporting a reinforced concrete slab deck. The erection of the girders in the 336-foot main span across the canal had to beundertaken without affecting shipping, which included ocean-going vessels of up to 12,000 tons and the contractors completed this difficult operation by cantilevering the girders from each side of the crossing.

4.3.4 The main works, which included a further seventy-nine bridges of various designs, began in February 1961.

4.3.5 Early site investigations had identified a wide variety of soil conditions, with clays of varying plasticity, soft and hard grey shales, dry and very wet sands, peat, sandstone and even coal, all of which required different forms of treatment.

4.3.6 For 13 miles, the motorway passed through mining areas and in several places the seams were exposed during construction. Some 13,000 tons of good quality coal were excavated and handed over to the National Coal Board, which had rights of ownership. Unrecorded shallow mine-workings were also found and, depending on their depth, were either back-filled or protected by reinforced concrete slabs, as were many old mine shafts, some up to 900 feet deep.

4.3.7 Future subsidence was expected over a length of almost ten miles and the carriageways, drainage systems and eight bridges were designed to cater for up to 13 feet of settlement.

4.3.8 A feature of the southern part of this section of motorway was the presence of bunter sandstone. In many of the cuttings it was encountered during excavation and, not only did it provide an excellent formation, but the material taken out was used both in the construction of embankments and as a sub-base for the carriageways. Additional material of this type was obtained by the Contractor from a major borrow pit alongside the motorway, thereby reducing the amount of construction traffic on the local road network if other sources had been used.

4.3.9 In contrast to the Preston and Lancaster By-passes, a stronger form of carriageway construction was adopted with, in general, a base of 6 inches of cement-bound granular material overlaid with 3 inches of dense bitumen-bound macadam. However, in the areas likely to be affected by subsidence, the bitumen-bound material was used for the full depth, to give greater flexibility.

4.3.10 Apart from the interchanges at the ends of this section, ie immediately north of Thelwall Viaduct and at Bamber Bridge south of Preston, there are seven other junctions with the existing road system of which three required the construction of substantial link roads. Whereas the all-purposes Winwick Link joined the A49 to serve the northern part of Warrington, the motorway-standard South Link and a new section of road at Shevington, north of the town, provided Wigan with full access to the motorway.

4.3.11 The first motorway Service Area in the North West was developed at Charnock Richard between Wigan and Preston. From the experience gained in the operation of Service Areas elsewhere in the Country, improved facilities within a better planned layout were introduced.

4.3.12 Whereas progress on both the Preston and Lancaster By-passes had been seriously affected by long periods of heavy rainfall, the memorable freeze-up early in 1963 brought work to a halt for a period of eight weeks. However, due to the considerable efforts of the Contractors, this section of motorway was completed by the Summer.

4.3.13 The motorway was already under construction through Cheshire and, in order to ensure that the traffic problems of Warrington would be relieved as soon as possible, arrangements had been made for the early completion of a 1 mile section from the A50 at Lymm to the southern end of the Thelwall Viaduct.

4.3.14 The whole length between the A50 and Preston was, therefore, opened to traffic in July 1963 with Thelwall Viaduct the longest motorway bridge in use in Britain at that time.

4.3.15 By the early 1980s, a serious situation had developed along the 6 miles of the M6 between the junction of the M56 and the M62. This heavily trafficked section of motorway had to cater for, not only North/South movement between the West Midlands, the North West, and Scotland, but also for East/West traffic between the Merseyside and Manchester conurbations, wishing to cross the Manchester Ship Canal. With traffic flows regularly up to 140,000 vehicles per day, the dual three-lane carriageways were frequently subject to queues and delays. The comparatively steep approaches to Thelwall Viaduct, and the absence of hard shoulders on the structure, added to the capacity problem.

4.3.16 Furthermore, inspections of the Viaduct showed that the deck was suffering from severe chloride contamination brought about by the effects of de-icing salt.

4.3.17 Pell Frischman Consultants Ltd were appointed by the Department of Transport to carry out a feasibility study into the options for increasing capacity on the section between the two junctions, and to consider the form of treatment necessary to renovate the deck of the Viaduct.

4.3.18 Both on-line, and off-line widenings to the east and west of the existing motorway, were investigated. The scheme which provided for upgrading to dual four-lane carriageways, including the construction of a new Viaduct on the east side of the existing span was the subject of a Public Inquiry held in May 1990 and the statutory procedures were completed in August of that year. Following detailed design, tenders were invited and work on the construction of the second Viaduct began in January 1993.

4.3.19 The new Viaduct, the centrepiece of the widening scheme, accounted for almost half the schemes cost. The structure, designed to complement its 30 year old neighbour, was commended by the Royal Fine Arts Commission for embracing advances made in bridge design and construction technology since the early 1960s. The new structure has integral cross-heads and a totally continuous welded plate girder deck which, at 4500 feet in length, is the longest such structure in the world. The majority of the twenty-six 170 feet long, spans are 1 times the length of those in the original structure, yet the deck girders are only marginally greater in depth. The piers consist of pairs of 7 feet diameter columns, except at the canal span where solid leaf piers provide the fixity for the deck. All the foundations are piled, the piles being an average 80 feet in length providing a mixture of end bearing into gravels and skin friction into clay. The deck is fixed to the pier nearest its centre point and each end can move by up to 24 inches to expansion and contraction between temperature extremes. This movement was a major consideration in the design, requiring particular attention during construction, when movement of up to 4 inches per day had to be accommodated.

4.3.20 In recognising the importance of future maintenance, the design included the provision of an access walkway beneath the full length of the Viaduct, with transverse walkways at the mid-point of each span. The spans over water were to be decked out completely.

4.3.21 Traffic management was paramount to the projects overall planning and design.

4.3.22 The programme required the construction of the new Viaduct, with conventional widening of the existing section of motorway to dual four-lane standards. The new Viaduct would temporarily carry all the motorway traffic, whilst the original Viaduct was being renovated under a separate contract. In April 1995 the first lane of traffic used the new Viaduct and, in the following month it became fully operational, by carrying three lanes in each direction.

4.3.23 The renovation contract included the complete demolition and reconstruction of the concrete deck; work on the substructures; modifications to the steelwork to reduce the number of expansion joints; the replacement of all bearings; and the installation of maintenance access facilities. The Contractor made the important decision at the outset that all the structural steelwork would remain in place, and that the renovation would be carried out half at a time, to enable longitudinal access to be available at deck level, at all times.

4.3.24 Apart from the work on the Viaducts, the scheme entailed the demolition of 14 bridges, sign gantries and retaining walls, and the construction of five overbridges and five underbridges, together with other major works.

4.3.25 The renovated Viaduct was opened to traffic in December 1996, thereby enabling dual four-lane carriageways, with hard shoulders, to be brought into use throughout the whole of the section between the two junctions.

4.4 THE M6 IN CHESHIRE

4.4.1 In 1955, it was reported that the County Surveyor had carried out some preliminary work on the design of the motorway within Cheshire. Further investigations were undertaken and, in May 1957, representations were made to the Ministry of Transport for the County Council to be appointed as Agents for the whole of the length between the adjoining County boundaries.

4.4.2 The terrain through which the motorway would pass, is rolling open countryside, containing many high-quality dairy farms. There were no serious difficulties in producing a free-flowing alignment with long sight-lines, to conform with the highest standards applicable at that time. Farm severance was minimised, and only a few cottages would be directly affected.

4.4.3 The Ministry was minded to employ Consulting Engineers and, in view of the resources which were considered to be necessary in order to meet the programme for construction, it was agreed that the work would be divided into two distinct sections. The Southern section between the Barthomley Interchange at the Staffordshire County Boundary and the proposed junction with the A54 at Holmes Chapel, was allocated to the firm of Scott & Wilson Kirkpatrick & Partners. The County Council, was to be responsible for the Northern section as far as the southern end of the proposed Thelwall Viaduct. The Consulting Engineers were also commissioned to design the bridges on the Northern section, thereby ensuring that all the bridges in Cheshire were of a similar pedigree.

4.4.4 However, on the basis of the earlier work carried out by the County Surveyor, the preferred route and vertical profile of the whole of the proposed 25 mile length of the dual three-lane motorway were established to the extent that the statutory procedures were then undertaken, and these were completed without undue difficulty.

4.4.5 On the 9 mile Southern section, only one intermediate interchange was required. At the junction with the A534, it would serve the small but ancient market town of Sandbach one mile to the west of the motorway. For many years, the town had been a popular stopping place for drivers using the A533, the A534 and the north/south trunk road A50. In the design of the motorway, provision was made for a Service Area to be constructed at a later date.

4.4.6 The Northern section intersected three major traffic routes along its 15 mile length. Interchanges were to be constructed, therefore, at the junctions with the A54 at Holmes Chapel, the A556 near Knutsford, and the A50 near Lymm. There was to be a Service Area at Knutsford.

4.4.7 The soil surveys indicated clays varying in plasticity, poorly graded sands with some of uniform particle size, silts, peat and rock. As a result of the high water table over much of the area, many of the sands were saturated and the clays were generally soft.

4.4.8 As a result of these investigations, a major amendment was made to the profile in the vicinity of the valley of the River Dane. This was done in order to reduce, as far as possible, the constructional and subsequent maintenance which would have arisen from a deep cutting through saturated sands overlying highly compressible clays.

4.4.9 A total of sixty one bridges was required along the 25 mile route, of which two carrying railways over the motorway, were the responsibility of British Railways.

4.4.10 It was advantageous to group bridges so that within a group they conformed, in principle, to a single design, although on account of differences in skew and width, variations in detail inevitably arose. Such grouping attracts the consequential advantage of speed of construction and economy. At the same time, it was recognised that it might produce a monotonous uniformity.

4.4.11 Certain bridges, however, required individual treatment. There were 10, of which the largest is a viaduct, 270 feet in length, carrying the motorway over the River Dane. Forty-five bridges carrying local roads over the motorway, and linking farms severed by it, were grouped into four types.

4.4.12 The foundations of the bridges varied according to the ground conditions, as ascertained from boreholes and, in general, either strip footings, driven piles, or cylinders, were used.

4.4.13 With the exception of the two railway bridges, concrete was used as the principal material of construction. The choice as to whether mass, reinforced, prestressed, pretensioned, post-tensioned, precast or cast in-situ design should be adopted was made after careful consideration, bearing in mind suitability, economy and aesthetics.

4.4.14 Separate contracts were awarded for the two Sections and work began in June 1961 with a period for completion of 27 months. However, provision was made in the Northern contract for the early completion within 24 months of the 1 mile section between the A50, at Lymm, and the Thelwall Viaduct. This was to enable the crossing of the Manchester Ship Canal and the River Mersey to be brought into use as soon as the construction of the motorway between Warrington and Preston had been completed.

4.4.15 As expected, the varied geology caused difficulty in carrying out the major part of the earthworks during 1962. The saturated sands could only be handled following extensive dewatering schemes. In the North, the Keuper Marls, which were classified as rock, required blasting techniques in order to carry out bulk, as well as, trench excavations, particularly in the construction of the Lymm Interchange.

4.4.16 The weather played a major part in the programming of the works when the whole of the site was brought to a standstill during the big freeze during the winter of 1962/63. In order to enable the roadworks to continue, a procedure known as Winter Working was devised by the Contractor and the Resident Engineer whereby only short lengths of formation, of the order of 50 to 100 feet, were exposed each day. These were covered by plastic sheeting, a 3 inch thick layer of sand, and a layer of sub-base as frost protection. Work was able to continue, albeit slowly.

4.4.17 North of Lymm, the motorway was opened to traffic in July 1963. A contract for the construction of 9 miles of the motorway in North Staffordshire had commenced earlier and the works were completed at the same time as those within Cheshire. The joint opening in November 1963 meant that there was then a continuous length of 87 miles of the M6 in use between Birmingham and north of Preston.

4.5 THE PRESTON-LANCASTER SECTION OF M6

4.5.1 The sections of the M6 through Lancashire, which had been completed earlier, provided By-passes of major centres of population. The section between Preston and Lancaster, however, was to have the effect of superseding a substantial length of the A6, where due to its unsatisfactory alignment, and the large number of junctions serving local traffic, congestion and the number of serious accidents had increased to an alarming extent. It would also close the gap in the M6 between Stafford and the northern end of Lancaster By-pass and increase its continuous length to 111 miles.

4.5.2 With no intermediate interchanges along its 13 mile length through an area which is rural in character it was, at that time, to be the longest stretch between junctions on a British motorway.

4.5.3 In order to minimise the extent of farm severance, the selected route was on the eastern side and immediately adjacent to the West Coast main line railway over a length of several miles. This had the effect of requiring an exceptional number of occupation bridges, over the motorway, to connect directly with those which had been provided when the railway was constructed in the 19th century.

4.5.4 Historically, all the north-south modes of transportation through this part of the country had followed a line on the eastern edge of the low-lying coastal plain close to the rising ground of the Pennine foothills. In consequence, therefore, within a corridor of less than half a mile wide south of Garstang there had been a Roman road; there was the Lancaster Canal still in use; there were traces of a turnpike road; and more recently, the main line railway; the A6 by-pass of the town constructed in the 1930s; and in the 1960s there was to be the motorway.

4.5.5 The southern interchange, at the northern end of Preston By-pass, had to cater for the future M55 serving the Fylde Coast. A conventional two-level layout with a roundabout would not have allowed continuous flow between the two motorways and so a three-level interchange was designed. It was the first of its kind in Britain and included the impressive eleven-span Fylde Junction Higher Bridge, 1300 feet in length. The main steel spine girder of box section 14 feet wide by 8 feet wide was welded in situ. Cantilever arms supported a reinforced concrete deck slab 44 feet wide between parapets.

4.5.6 The connection with the southern end of the Lancaster By-pass was to be a Trumpet type of interchange providing full free-flowing movement through to the roundabout junction on A6.

4.5.7 Tenders were invited for three different types of carriageway construction namely flexible, semi-flexible and rigid. The lowest, which was accepted, provided for 12 miles of the length to have the dual three-lane carriageways constructed in concrete. Concern had been expressed, however, about the performance of concrete roads in the UK both in terms of the design standards which were in use and the adequacy of the available plant. Arrangements were made, therefore, for a visit to be made to the USA by the County Surveyor, as Engineer to the Contract, the Resident Engineer, and representatives of both the Contractor and of the cement industry, to examine current practice.

4.5.8 A number of recommendations were made to the Ministry of Transport for approval to be given for changes to be made in the design and specification, one of the most significant being the means of catering for the expansion of the concrete slabs which were to be laid mechanically. It had been found in the USA that, with closer spacing of the contraction joints, it was possible to eliminate expansion joints, which are notoriously difficult to form and maintain. However, the Ministry was not prepared to agree to such a major change but accepted a compromise that the spacing of the expansion joints could be increased to a maximum of 480 feet with contraction joints 40 feet apart.

4.5.9 A semi-flexible pavement construction was to be used on the slip road carriageways at the interchanges, at the approaches to the underbridges in order to reduce the effect of any differential settlement, and in the hard shoulders.

4.5.10 The Contract commenced in September 1962 and was scheduled for completion in April 1965.

4.5.11 It was estimated from the soil survey that a considerable proportion of the 3 million cubic yards of bulk excavation in the boulder clays, sand, silt, peat, shale and gritstone would be unsuitable for use in the construction of embankments. Provision was made, therefore, in the Contract, for importing suitable filling, with a requirement that it should be used in forming shallow embankments and in a two feet thick layer at the top of all other embankments. The effect was to ensure a more stable and consistent formation below the carriageway construction, than might otherwise have been the case.

4.5.12 The Contractor was able to obtain planning permission to open a borrow pit in a gravel deposit adjacent to the motorway and from it, other materials such as selected filling to drain trenches were obtained. Subsequently, a landscaped lake was formed, which provided an attractive environmental feature.

4.5.13 It was somewhat ironic that whereas progress on other contracts in progress during the early months of 1963 was seriously affected by severe frost, these conditions facilitated the excavation and removal of large quantities of unsuitable material, which otherwise would have been very difficult in normal circumstances.

4.5.14 Laid on a sub-base of crusher-run limestone, the 10 inches thick reinforced concrete carriageway slab was to have a lower layer 7 inches thick using limestone aggregate and a top layer with a granite aggregate to give a high skid resistance.

4.5.15 The Contractor adopted various methods unique to Britain by employing items of specially imported equipment to form a concreting train. In order that it should operate as efficiently as possible, it was essential that it should be able to move forward at a steady rate. The earthworks, drainage, carriageway base and the majority of the forty-four bridges had therefore to be completed by the spring of 1964, to enable the concreting to be carried out during the summer. The concreting train could lay, in a single operation, the full thirty-six feet width of the slab for one of the carriageways. The maximum length laid in a twelve-hour working day was 2520 feet, a European record at that time.

4.5.16 In January 1965, this section of motorway, including the Service Area at Forton, was opened to traffic (6) and the Snowhill Lane bridge carrying a minor road over the motorway at Scorton, received a Civic Trust Award. Apart from a short length of 3 miles north of Carnforth, the M6 in Lancashire was then complete.(7)The design and supervision of the construction of the whole of the 62 miles of motorway with interchanges, 174 bridges and 12 miles of link and slip road had been undertaken by the County Council as the Agents for the Ministry of Transport.

4.6 PENRITH BY-PASS

4.6.1 The Market Town of Penrith and the City of Carlisle had long been in need of relief from traffic congestion. Apart from the effect of local traffic movement, they both lay at the junction of major traffic routes. The most important factor, however, was the influence of the London-Carlisle-Glasgow-Inverness Trunk Road A6 passing through the centre of the two urban areas.

4.6.2 In particular, Penrith suffered from the effect of what was known as Arnisons narrows, a single lane section of the A6 controlled by traffic lights. A similar constriction existed in the village of Eamont Bridge.

4.6.3 A report was prepared as long ago as 1930 on behalf of the Cumberland and Westmorland County Councils, and the Penrith Urban District Council, which considered eight proposals for by-passing Penrith. However, it was not until July 1962, when through traffic volumes had reached 25000 vehicles per day, that the Ministry of Transport invited Cumberland County Council, as the Agent Authority, to carry out surveys and prepare a scheme. Fourteen different possible routes were considered before the chosen route was finally selected.

4.6.4 The southern starting point of the By-pass at Hackthorpe, where a temporary junction with the A6 was to be built, was determined by the Ministry in conjunction with Scott & Wilson Kirkpatrick & Partners, who had been appointed for the design of the motorway through Westmorland. The topography did not favour a route to the east of the town and it was considered that a western by-pass would provide better opportunities for east-west connections.

4.6.5 Approximately halfway along the eight mile length of dual three-lane motorway, and close to the Town, it was proposed that a two-level interchange should be constructed connecting the A66 Trunk Road to the motorway. From the interchange, major works were to be carried out on the A66 route, involving the construction of 2 miles of new dual two-lane carriageway in each direction, westwards towards Keswick and Workington, and eastwards towards Scotch Corner and Middlesborough.

4.6.6 A further two-level interchange was to be provided as a northern terminal at Catterlen, but this was at the time considered to be temporary, until the motorway was extended northwards. There were to be link road connections eastwards to the A6, and westwards to the B5305, the route to Wigton.

4.6.7 At public meetings, where the proposals were described, the benefits to the Town Centre which the motorway would bring, were recognised. More detailed discussions took place with major landowners which proved to be particularly fruitful. The Lonsdale Estate was affected over the major part of the route and was prepared to consider modifying farm boundaries in such a way that there would be a reduction in the extent to which tenancies would be split by the motorway, thereby reducing the number of accommodation bridges.

4.6.8 In the design, a great deal of care was taken to ensure that the effect on the environment was reduced to the minimum by, ensuring that,

i. the horizontal and vertical alignments were coordinated to avoid optical kinks,

ii. earthworks were rounded, and landscaped by making use of surplus materials

iii. deep cuttings were taken out on a curve to avoid interference with the skyline, andiv. a visibility envelope was prepared to examine the effect of the motorway on the adjoining land, and vice versa

4.6.9 The statutory procedures were completed without significant problems.

4.6.10 The Contract for the construction of the motorway was awarded by Cumberland County Council with a starting date of the 1 November 1966 and a period for completion of 27 months.

4.6.11 From the site investigations which had been carried out it was found that boulder clay was the predominant soil type. Full scale trials had been undertaken before the award of the Contract, the information having been made available to all tenderers. Because of its silt content, the clay was very moisture susceptible but the materials with the higher moisture content were easily distinguished as unsuitable for use in embankment construction,

4.6.12 Because of the possibility of an increase in moisture content, bunter sandstone filling 12 inches thick was placed on the top of all embankments immediately below sub-base level to overcome loss of strength, and in cuttings, because of the frost susceptibility of the formation. An early example of the se of what came to be known as a capping layer, a practice adopted elsewhere in the construction of other lengths of motorway.

4.6.13 In all, 22 bridges were required. Three were designed by British Rail to ucarry the West Coast Main Line railway over the motorway and the new westerly section of the A66. The superstructures were of post-tensioned in-situ concrete, each built alongside the railway track and traversed into position using closed circuit television as a means of controlling the operation.

4.6.14 A variety of differing types of design were used for the other bridges, the most unusual being the Lowther Bridge. The substructure consists of four reinforced concrete skew arch ribs springing from bearings on thrust blocks founded on rock. A cast in-situ reinforced concrete slab deck is carried on two spans of Preflex beams.

4.6.15 In general, piled foundations were not necessary. In recognition of the location of the By-pass, on the fringe of the Lake District, masonry facing was used on thirteen of the bridges, with the majority in natural stone.

4.6.16 Earthworks started early in February 1967, and although the bulk of the operation was carried out before the end of September, a wet October prevented its completion as programmed. Abnormal weather conditions were experienced in March 1968, which caused further delay, and highlighted the need for additional river protection at bridge sites.

4.6.17 The works were completed three months ahead of schedule and the By-pass was opened to traffic on 7 November 1968.

4.7 THE M6 THROUGH WESTMORLAND

4.7.1 The various small-scale plans proposed during the 1930s for a network of motorways showed a line for the North-South route through Westmorland. It was, however, diagrammatic in that no detailed investigations had been carried out at that time.

4.7.2 The perennial difficulties of communications between Scotland and England because of the weather problems of the existing A6 route over Shap Saddle (approximately 1390ft), and keenly felt during the Second World War led to the concept of an alternative route via Tebay and the Lune valley. After the War this was taken up by the Ministry of Transport, and the route was surveyed and set out on the ground.

4.7.3 In 1959 a local resident called a meeting in Kirkby Lonsdale to protest at the route on environmental grounds. The unanimous conclusion of the meeting to condemn the route through the Lune valley was conveyed to the Ministry, who called in Consulting Engineers Scott & Wilson Kirkpatrick & Partners, to consider all possible and practical alternative routes between the end of the Lancaster By-pass and Penrith, and recommend the one to adopt.

4.7.4 Any route had to deal with an East-West mountain barrier at mid-point that was only relieved by a glaciated valley to the East epitomised by a length near Tebay known as the Lune Gorge. Either use had to be made of this valley or a more direct route had to be found using tunnels and/or high viaducts. In addition to the use of the Lune Gorge, tunnel routes making use of the Long Sleddale valley plus the Lowther or Hawerswater valleys, or along the line of the existing A6 to Shap village were identified: a viaduct route also on the line of the A6 was also identified. Numerous alternatives were found South of the mountain barrier, that could be combined with these resulting in some 30 possibilities to consider. These alternatives were discussed in an Interim Report submitted in mid-August 1960.

4.7.5 A number of special studies were undertaken. Aerial photographs viewed stereoscopically reduced the choice of routes to a few in number. Newly established techniques enabled maps to be drawn of probable depths of rock and the extent of various soil formations. An Origin and Destination survey was carried out so that traffic could be assigned to alternative networks.

4.7.6 Traffic on the A6 was frequently brought to a halt by wintry conditions with bad visibility a particular problem. For the first time on a motorway project, a meteorological study was, therefore, undertaken to judge the effects of wind, low temperature, snow and reduced visibility on traffic using the alternative routes.

4.7.7 The Final Report, in 2 volumes, was submitted by the Consultants in March 1962. In addition to the matters described above, the Report analysed the results of the various surveys and studies, and how they led to three alternatives for final comparison viz;-

Direct Route

Killington Route

Lune Valley Route

The alternatives were described in detail, and the effects of the following factors were assessed:-

Weather

Land Use and Landscaping

Capital and Maintenance Costs

Traffic Operating Costs

4.7.8 As a first stage, the Killington Route was compared in detail with the Lune Valley Route, and the conclusion was drawn that the Lune Valley Route was to be ruled out and that, if the chosen route was to pass through the Lune Gorge, then it should be the Killington Route.

4.7.9 The Killington Route was then similarly compared with the Direct Route. The choice here was less clear-cut. The Direct Route was shorter, but its capital cost was greater, due to the use of tunnels. A short single 3-lane, unventilated tunnel under Hucks Brow was to carry the climbing North-bound carriageway. Further North at the head of Crookdale, twin ventilated 2-lane tunnels 6,800 ft.long were proposed, one for each carriageway; a third 2-lane tunnel between these two was to be added when justified by traffic growth. This central tunnel could then be bi-directional, used only for climbing traffic, or tidal flow.

4.7.10 Emergency crossing places within and outside the tunnels were proposed. However, the total recurrent costs, comprising traffic operating costs, road maintenance costs, and, in the case of the Direct Route, tunnel operating costs, were shown to be less for the Direct Route even after the construction of the third tunnel.

4.7.11 A cost-benefit analysis showed a return of almost 9% on the additional cost of the Direct Route. Provided the extra capital was available the Direct Route was recommended as the best route from long term, and strategic points of view.

4.7.12 However, i) it was not possible to rank these returns with those from other road schemes for which the additional funds might be used, ii) the Direct Route was less effective from a weather viewpoint, and iii) the tunnels placed restrictions on the movement of dangerous goods. For these reasons the Killington Route was selected.

4.7.13 Apart from the terminal interchanges, it was only necessary to provide four junctions with existing roads along the 36 miles of the route.

4.7.14 In carrying out the design, great care was taken to fit the motorway to the landscape, and the designers found that the motorway alignment standards were particularly suited to the terrain, which mean that North-bound traffic would encounter long climbs along certain lengths and desirable constant gradients were achieved in all of these. The reduction of earthworks achieved by stepping carriageways in steep sidelong ground was utilised for 2.5 miles south of Killington, and for 3.5 miles in the Lune Gorge. In the latter case the vertical separation reached 30 ft.

4.7.15 North of Tebay the carriageways are separated over a distance of 4.5 miles, the maximum separation being 800 ft. North of Shap Interchange separation of carriageways occurs over a length of 2.5 miles. It was concluded that sheep farming could continue between the carriageways, and sheep creeps were designed along established sheep corridors to facilitate this. Protection from drifting snow for the vulnerable lengths North of Tebay was generally achieved by designing embankments with a minimum height of 2 ft and cuttings with side slopes flatter than 1 in 6.5.

4.7.16 It was decided to separate surface water and sub-soil drainage, the former being effected by a specially designed channel section, with an in-line graded approach with slotted steel covers to gulleys. The latter were buried and comprised standard porous pipes together with filter material designed to prevent clogging from the surrounding soil. In one area north of Dillicar Knott larger, deep intercepting sub-soil drains connected to the motorway drainage system were designed to prevent slips in the steep boulder clay slopes.

4.7.17 In order to make use of wet material, and as a result of experience gained from a full scale trial embankment constructed on the line of the motorway, embankments were designed to be laid in 8.5 ft layers separated from one another by drainage layers. In one area of steep sidelong ground deep intercepting sub-soil drains were used above the motorway for additional protection. In pre-determined areas excavation to a vertical face in cuttings was specified to minimise suitable material becoming unsuitable, after periods of rain.

4.7.18 Extensive use was made of computer programs in the calculation of horizontal alignment, intersection and merging geometry, and the setting out of horizontal control lines from setting out beacons. For the first time in this country, actual computer print-out was incorporated into contract drawings.

4.7.19 There are 160 structures on this section of motorway of which 77 are bridges or underpasses. Cost studies led to open abutments being selected generally, so that for standard situations overbridges have three or four spans, but most underbridges have single spans. In one case an overbridge carrying a minor road was designed with 3 spans rather than 4, so as to frame a magnificent early view of the approach to the Lune Gorge for North-bound travellers.

4.7.20 Within a length of 2.5 miles in the Gorge, 8 underbridges were required to carry the motorway, and 3 to carry the diverted A685. The 73 ft high Borrowbeck viaduct is close to and 10 ft higher than the stone arch railway viaduct carrying the West Coast main line to Glasgow. The central span of the curved motorway viaduct was designed to frame the railway viaduct when viewed from the realigned A685, itself on a new curved bridge over Borrow Beck.

4.7.21 The railway line had to be crossed in three places. These were all skew crossings, one having an extreme skew of 70. Precast reinforced concrete beams square to the tracks were used to minimise temporary works over the railway. For the smaller skews, the free edges followed the skew and a trapezium of reinforced concrete lapped with the precast beams to form a portal construction. For the extreme skew the bridge has beams square to the track throughout, with sections protruding on either side of the motorway construction above.

4.7.22 The location of Service Areas was treated as an environmental as well as an amenity matter. Connecting overbridges were avoided, and sites were selected alternately for North- and South-bound traffic with the two southernmost ones widely separated. However, where the carriageways are separated North of Tebay they are opposite one another. All are designed to provide views away from the motorway, and at Killington the Service Area overlooks the Reservoir and is well screened from the motorway by ground contours.

4.7.23 Construction was to be carried out under five separate contracts for each of the five sections. Contract periods allowing for two full winters of earthwork construction were considered essential. The contract for the section through the Lune Gorge, because of its major structures and large quantities of rock excavation, was given a lead time of 10 months over the other contracts when tenders for it were invited in October 1966. Construction commenced in October 1967.4.7.24 Jeffreys Mount provided a planning challenge for the Contractor. The A685 was on the line of the M6, and had to be diverted up-hill to the West as an initial task prior to the construction of the motorway itself. Both A685 and M6 had to be excavated to form ledges in the steep rock with the West Coast line immediately below the latter. Pre-splitting techniques were suggested to tenderers as a suitable technique for avoiding overbreak, and to maintain the stability of up-hill slopes or construction. This technique was used extensively and successfully in this location.

4.7.25 In the event, the condition of the exposed rock proved more difficult than could have been anticipated from visual examination of exposed surfaces, and drill-hole results. The adopted solution was to use rock bolting, previously a little known technique. It was used extensively to good effect.

4.7.26 Where the motorway runs close to and above the railway on steep sidelong ground near Dillicar Knott, a safety fence comprising anti-submarine netting fixed to steel rails concreted into the ground was erected prior to commencing earthworks. It was tested successfully by using a runaway D6 crawler tractor.

4.7.27 Also in the Lune Gorge, site access was very difficult, and a preconstructed continuous haul road off the motorway alignment was considered to be imperative. Imported rock from a disused quarry was used to supplement the rock excavations through Jeffreys Mount and around Dillicar Knott at the entrance to the Gorge. The former provided a continuous source of input to a crusher sited nearby. Material from the haul road was subsequently re-excavated to provide material for drainage layers elsewhere.

4.7.28 Bailey and Callendar Hamilton temporary bridges capable of taking 35 ton loads were used where the haul road crossed the River Lune. The 8,300 ft realignment of the A685 was a first priority, and intricate programming was involved in completing this section.

4.7.29 The motorway was opened in October 1970 with a maximum elevation of 1036 ft compared with that of the A6 it replaced of 1390 ft. It received a Civic Trust Award and the following wording appears on a plaque in a lay-by off the A685 overlooking the Lune Gorge:-

This award for an outstanding contribution to the appearance of the Westmorland landscape relates to the 36 miles of M6 Motorway between the Lancaster and Penrith by-passes.

4.7.30 From the interchange at the junction with the A65, it was the intention to provide a new high-standard dual-carriageway road running in a north westerly direction as an improved means of access to South Lakeland. To be known as the Kendal Link, it was to be an all-purpose road and not a motorway. In accordance with Ministry policy, the future maintenance of the boundary fence would, therefore, be the responsibility of the adjoining landowners.4.7.31 The road was to pass through a deer park and special deer-proof fences would be required. Initially, the landowner concerned raised no objection to the principle of providing the road, but was not prepared to accept responsibility for the fences which were to be erected as accommodation works with the cost met by the Ministry. He,