Tunnel cure for paralysed Tipton
A £22 million scheme to replace the last level crossing on the Euston- Wolverhampton route with a tunnel took a major step forward over Easter with the sliding-in of a box structure under the railway.

BAM Nuttall Ltd was awarded the contract to design and construct a relief road in August 2007, helping ease the severe road congestion caused by Tipton level crossing near Wolverhampton which, during peak periods, can see the barriers lowered for as many as 45 minutes in every hour. Due to the huge amount of passenger and freight traffic using this corridor, it has not been uncommon for the barriers to remain down for 20 minutes at a time. The problem is so acute that buses are no longer routed over the crossing for fear of being heavily delayed. Come October, all this is set to change with the opening of the relief road which will cross the site of the Tipton Station's former car park before passing under the railway some 300 metres south of the present crossing, which will then close. Also closing will be Watery Lane shunt frame which monitors the crossing and gives the slot to Wolverhampton panel signal box for the protecting signals. The existing pedestrian subway under the line is to be retained and enhanced.

Three hydraulic jacking rigs
A major possession began at 0030 on Friday 9th April and, during this time, the 6,500-tonne box - which is 58m long, 19m wide and 9m high - was slid into position using three hydraulic jacking rigs, each with a maximum thrust of 1,200 tonnes. The maximum combined thrust used during the four days was 2,165 tonnes.

Steve Beech, BAM Nuttall's project manager for the scheme, explained that installing a tunnel beneath a railway is usually the last option when all other possibilities have been explored. "But the cost of an overbridge was prohibitive due to the level and concentration of the neighbouring highways, businesses and housing. Other alternatives considered included a different location some 800 metres away but that was rejected because the local community wanted the bridge near to the town."

Before the box could be built on site, a casting basin had to be constructed where, over 40 years, a long-disused canal basin had been filled with rubbish. This was a relic of when the main line canal branched off at this point, passing beneath the railway.

To assist movement of the box during the operation, the tunnel has a plated steel soffit and was constructed on top of 120 steel wire cables that were laid on the jacking slab. To help the sliding action, grease was applied to the wire ropes and Benotite - liquid clay – was injected into the front of the tunnel to increase lubrication between the tunnel walls and the embankment. In addition, as the box moved forward, a further 512 steel wire ropes were fed under the tunnel to form a track, ensuring that the sliding action was always between the steel soffit plate and the greased wire ropes, as opposed to the ground. This method allowed the box to be jacked forward by an average of 1.7 metres every hour.

Local recreation area
The project has seen 60,000 tonnes of spoil excavated from the site, with 50,000 tonnes of this being used to landscape and create new playing fields for a local recreational area. The remainder was too contaminated to be reused and has gone to a landfill site. 12,000 tonnes was excavated during the Easter blockade.

The line was handed back to Network Rail at 0230 on Tuesday 14th April, 21⁄2 hours ahead of schedule.

Article courtesy of The Rail Engineer - may 2009


Further Info
Peter Bishop - Head of Public Relations & Corporate Communication
BAM Nuttall Limited
St James House, Knoll Road, Camberley,
Surrey GU15 3XW
Tel: 01276 63484
Fax:01276 66060
peter.bishop@bamnuttall.co.uk