The Intercity Express Programme (IEP) is to deliver a fleet of new long distance trains onto the railway network to replace the current intercity fleet and ultimately increase passenger capacity. As part of the IEP, VolkerFitzpatrick have been appointed by client Hitachi Rail Europe to develop and construct a number of train maintenance depots and associated infrastructure. The main facility in the South West is located at Stoke Gifford Junction, North Bristol in Avon.
As part of these works it is proposed to design and construct a replacement for the existing Stoke Brook culvert which runs across the site. The existing culvert passes under two sections, one owned by Hitachi Rail which is 654m in length, and the other shorter section of 338m by Network Rail. Each site is bounded to the east and west by rail tracks under which the water is transferred by existing masonry structures.
VolkerFitzpatrick appointed VolkerGround Engineering as a specialist sub-contractor to design and construct 1420 AZ 28-700 sheet piles, 7m in length that could provide the basis of a new drainage structure across both sites. VolkerGround Engineering provided early involvement with the group design team, working with Arup engineers in order to compile the most cost effective engineering solution for the project. Piles were driven through the made ground with a vibratory hammer and through the underlying stiff clay and to practical refusal in the strong mudstone bedrock by an impact hammer, both mounted on VolkerGround Engineering's 16/20 hydraulic leader rig.
The main issues in the completion of the works were the variable rock strengths underlying the site which meant that sheet piles were terminated, in places, at a lesser depth than was envisaged. The extent of the culvert works were also confined to an area between two existing rail lines, and within fill that was known to be contaminated.
Early involvement with the project's designer was a clear lesson learnt in that VolkerGround Engineering were able to provide a value engineered scheme for the culvert structure avoiding additional cost lengthy subsequent delays in the main works construction in this enabling works element of the scheme.