Preston By-pass

Before the motorway was constructed, the A6 through Preston handled north-south traffic with tailbacks and congestion a common occurrence, more so during special occasions such as the Blackpool Illuminations. The route had been planned as far back as 1937–1938,[1] with the basic alignment still deemed feasible by the time Lancashire County Council gave approval in the mid 1940s. Chief engineer Drake was part of a delegation from Lancashire that travelled to Germany in 1938 in order that a plan could be drawn up by the council. The agreed route formed part of the County Surveyors' Society's national proposals and was protected by Lancashire County Council from any future developments.[2] During planning, the legal powers necessary for motorway construction did not exist, until the introduction of the Special Roads Act in 1949 that made it lawful to construct roads that were to be used only by certain classes of vehicle.[3] The bypass was seen as an experiment for future motorway construction, with many lessons and techniques being learnt that would contribute to the success of future projects. When the proposals were made public, including a large-scale model to ease the explaining of the scheme, only a handful of formal objections were raised and were resolved by agreement without the need to initiate a public inquiry, cited in part because of close personal involvement of Lancashire County Council and the surveyor during consultation.[4]

The Tarmac Group won the construction bid in 1956, including 19 bridges; John Cox was the onsite engineer assigned by the contractor to oversee the construction.[5]

The bypass under construction, 5 December 1958

The road was originally built with two lanes in each direction, but with an unusually wide central reservation to accommodate a third lane to be added each way at a later date. The work was a compromise between the Ministry of Transport and Drake, the latter thinking that two lanes would not be adequate. Initially, the shoulders were hardened with gravel but not paved,[6] a fact still reflected in the British term hard shoulder. A hedge was planted along the length of the central reservation to help reduce dazzle from the headlights of oncoming traffic at night. The road was constructed not to be a long stretch of straight road and with the addition of various bridges and tree planting, in the hope to prevent driver boredom reported on foreign motorways.[3] During the early months, some of the land was not available for contractors, as there were 75 agreements in place with land owners, with some, such as farmers, having clauses allowing them to complete that year's harvest prior to construction work commencing.[7]

The earth material used for the embankments was planned to come from the road foundation works, but rainfall meant it was no longer fit for purpose, so hundreds of thousands of tons of hard filling was imported from around Lancashire. Earth-moving works could only be done efficiently through March to June, while conditions from July to October would be too sodden and not possible at all during winter.[7] In total, 3,400,000 tonnes (3,300,000 long tons) of earth was excavated, with a further 668,000 tonnes (657,000 long tons) of material imported for filling.[3] The sub-base consisted of burnt colliery shale with thickness dependent upon the ground conditions, followed by a layer of wet mix around 9 inches (23 cm) thick and topped with 2 to 3 inches (5 to 7.5 cm) of tarmac lined with 0.5 to 1 inch (1.3 to 2.5 cm) of asphalt. A newly discovered and unexpected bog in the Ribble valley also required removal.[7] A total of 22 bridges were required in construction, and designers were given relative freedom in planning them. Chief engineer Drake proposed the bridges be painted different colours to enhance aesthetics and help alleviate driver boredom, contrary to conventional practice of using neutral colours; drivers subsequently reacted favourably to alternately coloured bridges.[4]

The contracted period for construction was planned to be around two years, but the timescale was lengthened by nearly 25% due to rainfall that persisted throughout much of the early construction period. The heavy rainfall in late 1956 had profound effects on the heavy engineering works required to construct the road foundation, resulting in this aspect of work being postponed until early 1957.[3] During the first nine months of construction, working conditions were so bad that the main contractor, Tarmac Ltd, had an extension of five months granted due to the extraordinary and unforeseen weather conditions, pushing the date of completion back to 30 November 1958. At its peak, 750 men and around 24 engineers were working on the road's construction, as well as 50 crawler tractors, 24 excavators, 12 dump trucks and around 100 lorries.[7]

Numerous lessons were learnt from the construction of Britain's first motorway, particularly towards using an appropriately screened base material, with water drainage systems that should be appropriate and fit for purposes, as well as the inclusion of continuous hard shoulders.[4]

Plaque to commemorate the opening of the bypass

The bypass was opened on 5 December 1958 by the Prime Minister, Harold Macmillan. It had cost £2,960,481 (equivalent to £73,582,626 in 2021), of which almost £2.5m was for construction of the motorway itself and over £500,000 was for the construction of two required major bridges, those being the Samlesbury Bridge (£334,431) and the High Walton Bridge (£193,690) respectively.[3] It was estimated that around a third of a total cost was on the bridges alone, a point questioned by the Birmingham Post, who noted that in percentage terms, it would not have cost significantly more to build the motorway as three lanes, compared to doing so retrospectively in the years to follow.[8]

Macmillan became the first man in Britain to travel on a motorway, as a passenger in an Austin Sheerline limousine, setting off from what is now junction 31 on the M6 motorway.[9] Many hundreds of people gathered at the interchange in Samlesbury to witness the official opening, of whom many had participated in the construction and were proud of what they had achieved.[5]

An additional third lane was added in each direction in 1966 using the land reserved within the central reservation, without the need to modify existing bridges. Despite the relative ease in this work, the lack of hard shoulders at the bridges meant the number of available lanes during engineering works was inadequate to cope with the traffic volumes of the time, estimated to be have been in the region of 140,000 vehicles daily.[4] Construction of the M61 motorway in 1969–1970 to carry Manchester traffic northbound had its northern terminus connect to a new junction on the bypass at Bamber Bridge, requiring the construction of Blacow Bridge to carry the north-bound M61 traffic over the M6.[19]

The bypass underwent significant work during the early 1990s, when it was completely rebuilt to become four lanes in each direction. All of the bridges needed removing so a hard shoulder could be provided, despite most of them having a design lifespan of 120 years.[5] The bid to undertake the work was awarded to Balfour Beatty in February 1993, at a cost of £37,458,986[20] (equivalent to £81,176,000 in 2021).[17] The upgrade meant that the bypass was entirely reconstructed and is now effectively a different motorway to the original bypass.[21] The four-lane motorway had been initially proposed back in 1924, when the idea was quickly dismissed after pressure mounted from railway lobbyists.[22]