M6. Birmingham to Preston Motorway (J13 to J16)
History and Background
Consideration was being given to the construction of 'a motor route' between London and Lancashire during the 1939 1945 war.
There were extensive consultations between the Ministry of Transport and Local Authorities which resulted in the decision on a line skirting the north east of Birmingham, passing to the west of the Potteries, then to a midpoint between Liverpool and Manchester and onto Preston and Lancashire, one of the main aims being to provide much needed bypasses to many towns along the route. These bypasses were to be given priority for construction ahead of the detailed planning for the rest of the route. Hence the construction of M6 commenced on the Preston Bypass in 1956 followed by the Lancaster Bypass which was completed in 1960.
In Staffordshire, the detailed route planning and design of roads and bridges from A449 South of Stafford to the Cheshire boundary was entrusted to the County Roads and Bridges Department under the County Surveyor Fred Jepson. The design teams were assembled in 1957 with priority being given to the preparation of the section that would form the bypass to the County Town of Stafford to relieve the intolerable traffic congestion on the A34 which passed through the centre of town.
Route Location and Design
North of Stafford the most appropriate route for the majority of the length appeared to be just to the east of the main Stafford Crewe railway line, passing as close as possible to Stoke then carrying on to the County boundary where an appropriate crossing place near the village of Barthomley had been agreed with Cheshire County Council.
Close examination of this route showed that a viable line could be obtained both horizontally and vertically within the Ministry of Transport terms of reference a minimum radius of curvature of 3,370ft and maximum gradient of 1:36. The road was to comprise of dual 36ft carriageways, 10ft hard shoulders and 13ft central reserve with the verges and marginal haunches making a total width of 118ft at formation level.
The section of the route in the vicinity of and bypassing Stafford had to be to the West of the town and would involve crossing the River Sow, the peat bogs in the flood plain and the main Stafford Crewe railway line. It was therefore decided to construct this section on a viaduct approximately half a mile long.
North of Creswell the line passes through undulating agricultural land used at the time mainly for intensive dairy farming. This required the construction of numerous 'cattle creeps' for the movement of cattle between areas of severed land.
Further north to minimise the impact on the natural beauty of the landscape the route followed the foot of the Beech escarpment before skirting Trentham Park and the attractive parkland surrounding Keel University.
Beyond this section the line had to deflect through more than 900C with long sweeping reverse curves to negotiate a path through the site of old coal mine workings and clay pits. This involved side cutting through a mile of heavily wooded hillside at Walton's Wood (where the Compleat Angler once fished) and which turned out to present the most difficult geological problems encountered on the project.
Pavement design in general was calculated in accordance with the latest publications of the Road Research Laboratory using the CBR method. The minimum construction depth of 20" being used as the standard which comprised 4" hot rolled asphalt 10" cement bound granular base and 6" sub-base. The sub-base being thickened in additional 6" layers when CBR tests near formation level proved this to be necessary.
Interchanges linking the motorway to all-purpose roads were provided as follows:
The 27 mile length in Staffordshire was divided into 5 contracts for the purpose of accessibility, complexity of construction and each to approximate to balanced lengths of cut and fill of earthworks. This resulted in following contract lengths:-
The link road from north of Stafford to the A34 was also included in Section A contract. Two further contracts for the link roads to Stoke South and Stoke North were let separately.
The Stafford Bypass section was given priority for detailed design and construction and as this length included the crossing of the River Sow flood plain by viaduct it was decided to prepare and let an advance contract for this structure.
The viaduct section , over 2000ft long, consists of a series of pre-stressed concrete bridges one of 5 No. 80ft spans, one of 4 span and one of 3 linked by embankments. The motorway being carried at a height of 20-30ft across the river, the main Stafford Crewe railway and the peat bogs in the flood plains.
The embankments are placed on a 15" reinforced concrete platform which is carried on 7000 ground piles. The earthworks are contained within retaining walls which are then concealed by the outer slopes of the embankments.
A contract for this phase amounting to £1.2 million was awarded to J L Kier Ltd in August 1959 and this part of the bypass was completed in March 1962.
Section A contract for the remaining length of Stafford bypass and for the ¾ of a mile link road to A34 was awarded to J Laing construction in June 1960 in the sum of £2.68 million.
The preponderance of bridges are a feature of this contract length, there are 28 excluding the viaduct in the 5 mile length with as many as 7 within 900 yards.
A518 Newport road had to be lowered some 23ft for the motorway to pass over which involved the removal of 50,000 cubic yards from the crown of the hill.
Particularly wet conditions were experienced during the earth moving season commencing in Spring 1961 and rain on 39 days out of 41.
The bypass linking the A449 in the south to the A34 north of Stafford was officially opened by the Minister of Transport Mr Earnest Marples on August 2nd1962.
In October 1960 the Minister of Transport authorised Staffordshire County Council to accept the tenders of John Laing Construction for all three remaining contracts to construct Sections B, C and D. the total tender sum for this work which comprised 19 miles of carriageway and 45 bridges totalled £7.1 million.
The award for all 4 contracts to one Contractor did allow better co-ordination of the various phases of work and to maximise the best use of specialist skills and equipment.
At the height of the constructions period over 600 men were employed and to accommodate this largely itinerant workforce and their families, the Contractor established a base camp at a former police training hostel at Mill Meece, some 3 miles from the midpoint of the motorway site. This facility included family and single accommodation, recreation facilities and also convenient access to local schools.
The site also provided the project headquarters for both Contractor and Resident Engineer staff.
Most of the granular sub-base, the aggregates for the CBGB and the structural concrete were obtained from a large unused gravel pit which was on the line of the motorway at Trentham Park. Hence the Contractor erected aggregate processing and concrete batching plants, the material being supplied to two other mixing sites at the North and South ends of the contract.
Concrete work on Sections B, C and D commenced in January 1961 and were completed in December 1962.