Project Category : Infrastructure, Rail Network
Project Name : Stansted Express Line Rehabilitation
Client : Optimise Water LLP
Location : Bishop’s Stortford, Hertfordshire
Value :  Undisclosed
Project Overview : The McAllister Group was charged to complete a ‘free in air’ liner installation under the critical Stansted Express Rail Line into Central London.
Issues to consider : Project was timebound to complete in a 48-hour period on the 2nd/3rd January 2016. A section of brick culvert under the railway line was severely deformed and broken in several places. The brick culvert was 600mm in diameter but this was reduced to 480mm at the deformed section.
Works preparation : CCTV Investigation of culvert followed by analysis of the flow volumes and structural requirements.
Solution : A design was agreed to install a 480mm liner with a full pre-liner to avoid over inflation in the 600mm pipe. The annulus between the liner and the brick culvert was then filled with grout.
Outcomes : On site the first McAllister team were tasked with all the pre-cleaning, pre-surveying and installation of the liner. Work started at 6am on the 2nd January and the liner had been successfully installed. The second phase took over operations to carry out the grouting works and the reforming of the manhole to allow discharge from the track draining. The second phase of works was completed by 4am within time and budget.