“The M25 Just Gets Wider & Wider!”
… And at Chiltern Thrust Bore we have probably put more crossings in than anyone, working on most stretches of the M25 in the past few years. Maybe the jobs are becoming so complex that few have the skill and confidence to deal with them?
That was certainly the case on the A2/A282 job. As one of the busiest sections of road in the UK, traffic management was the most important consideration and so we had the nightmare of working from the central reservation to the hard shoulder.
With no access to the exit side of the crossings we had little choice – perhaps that’s why no other firm would take the job.
Our recent successful work for Costains with Thames Water showed we could clearly handle this job - 12 crossings to put drainage under the main road.
We deployed our BPU800 Augur Boring Unit alongside the BM400 to deal with diameters ranging from 500mm to 900mm, but the nature of the job meant we had to invent a new system based on an adapted German version.
Each crossing took 4 days but we had to take on all tasks – not just the specialist work – including the work shafts; all the temporary and permanent works and all lifting and attendances. But it kept Costain’s main contract on track.
It helped that we had a superb Kiwi engineer, Tony Hodges, seconded to us for the period of the contract - if only because the Rugby World Cup ran out on him well before it ran out on our lads!
Three months later Chiltern Thrust Bore was again Costain’s contractor of choice when the next M25 contract came up. We needed to push through 50 metres of 300mm Denlock Clay 1 x 500mm steel and 1 x 600mm steel. The big machine came into its own for putting a 900mm steel in under a Thames Water 700 diameter high pressure main.
We met all the lines, levels and tolerances within 4 days - 6 days ahead of schedule.