The Polesworth Contracts of the Tamworth Section of the M42 Birmingham to Nottingham Motorway extend from the A5 at Dordon to the junction of the A453 and A444 at Appleby Magna, a distance of 12km of dual two-lane motorway.
Initial work for the Polesworth Sub-Section was carried out by the Staffordshire Sub Unit of the Midland Road Construction Unit before Derbyshire Sub-Unit took responsibility for the scheme in 1973. In 1981, Scott Wilson Kirkpatrick and Partners took over the Derbyshire Sub-Unit and became responsible for the Polesworth Sub-Section.
The Sub-Section was divided into two Contracts for the purposes of Construction. The Contract for Polesworth South was awarded to Tarmac (now Carrilion) Construction Limited in late 1983 and the same company was also successful in winning the Polesworth North Contract in mid 1984.
The Polesworth Sub-Section starts near Dordon , proceeds through gently undulating farm land, to the west of Polesworth where it crosses the River Anker Valley on a high embankment. After flat farm land it passes through the prominent ridge at Salt Street and terminates at the Appleby Magna Interchange which forms a junction with the A453 and A444.
The southern part of the route is underlain by the Upper and Middle Coal Measures with areas of colliery waste fill and river terrace gravels adjacent to the River Anker. Two abandoned coal mines occur near the road line at Birchmoor and Pooley Hall Collieries.
Open hole and rotary core drilling was carried out to explore the possibility of abandoned mine, workings. Two mineshafts adjacent to the Coventry Canal were drilled and grouted and a reinforced capping slab was constructed at rockhead level.
The embankments from south of the canal to the London-Crewe mainline railway were surcharged and subject to a delay period to allow for settlement.
At Bramcote Hall Track, the Warton Fault occurs at the north east boundary of the Warwickshire Coalfield. This is a major geological fault with a 300 metre downthrow to the north where keuper marls, siltstones and sandstones of the Triassic Series overlie the coal measures.
The Bramcote cut is partly in coal measures with some boulder clay and partly in marls and mudstone. The 15 metre deep cut at Salt Street is entirely in marls and mudstone.
The motorway pavement is of flexible construction with a composite roadbase of lean-mix concrete and dense bitumen macadam. The pavement is founded on an imported granular capping layer which effectively reduces the required depth of the more costly pavement construction materials.
The flexible pavement construction consists of 40mm of Hot Rolled Asphalt Wearing Course on 60mm of Dense Bitumen Macadam Base Course, on 100mm of Dense Bitumen Macadam Roadbase, on 210mm of Lean Mix Concrete Roadbase on 150mm of Type 1 Sub-Base and 260mm or 550mm of an Earthworks capping layer.
There are no permitted outfalls for carriageway drainage between the site of the old Birchmoor Colliery and the River Anker a distance of nearly 3 kilometres. Carrier drains have had to be installed varying in size from 375mm diameter to 600mm diameter. The drainage crosses the canal in two steel pipes of 450mm diameter hung from the underside of the bridge and a 600mm pipe has been constructed in a thrust bore under the railway line.
Between the River Anker and the Salt Street Ridge the carriageway drainage is discharged into Bramcote Brook.
The motorway ends in a cut at the Appleby Magna Interchange and there was no gravity outfall to the River Mease until the A42 was constructed. In the meanwhile storm water had to be pumped into a ditch running along the A444 before eventually discharging to the River Mease.
Extensive improvements had to be carried out to both Bramcote Brook and the Mease outfall to cope with the rapid run-off from the motorway.
There are six bridges carrying side roads and a farm road over the motorway and four carrying the motorway over side roads, a canal and the railway. Three more bridges carry farm accommodation roads over the motorway whilst one bridge allows a farm accommodation road to pass beneath the motorway. A five span viaduct carries the road over the River Acker and its flood plain.
The most impressive structure is the reinforced concrete elliptical arch bridge which carries the ancient ridge road of Salt Street over a deep cutting through the ridge. The overall span is 114 metres. A jacking system was incorporated into the design to facilitate adjustment at the arch footings to counteract any unacceptable stresses that could be induced in the arch by excessive ground movements during construction. The bridge was monitored for movement and strain during and after construction and in the event jacking was not considered necessary and the arch footings were concreted solid.
The River Anker viaduct is longer has five spans of 26 metres each. The simply supported structure has a precast prestressed standard `U' beam composite deck with spill-through abutments and intermediate piers founded on spread footings.
The main London to Crewe railway line is crossed by a two-span structure with a standard 'M' beam composite deck. The south abutment is founded on 1050mm diameter bored cast in place piers whilst the centre pier and north abutment are founded on 600mm diameter piles.
The bridge over the Coventry Canal is also founded on 1050mm diameter piles. The single-span bridge has a standard `U' beam composite deck. Provision was made for a haul route for British Coal to pass beneath this bridge and the railway and river bridges.
The road overbridges are continuous four-span in-situ reinforced concrete decks supported on bank seats and intermediate columns founded on spread footings. The road underbridges are a single span `T' beam deck on reinforced concrete cantilever abutments and a single span `M' beam deck on reinforced concrete cantilever abutments.
Three accommodation overbridges are three-span in-situ reinforced concrete decks with voided centre spans supported on concrete piers and skeletal abutments. The accommodation underpass at Dingle Lane is a reinforced concrete single-cell box structure.
