The decision to use a moving hopper at Westbourne Park stems from a need to rapidly move spoil away from site, a source close to the project said this week.
The source said direct loading from a tunnel boring machine (TBM) onto a freight wagon was unusual. However, the decision to use this system by contractor BFK - a joint venture consisting of Bam Nuttal, Ferrovial and Kier - was driven by the fact that the Westbourne Park site is so constrained and that there was a need to remove spoil by rail.
Crossrail’s narrow Westbourne Park site is hemmed in by the Great Western Main Line to the south, and local streets plus the A40 Westway to the north.
“It made sense to directly load into the wagon,” said the source. “Anything else would have been slower.”
Using a stationary hopper would have simplified the muck-away process, but there are other issues that must be tackled.
“It is very difficult to use a stationary hopper,” said the source. “You would have been shunting the wagons backwards and forwards - it would have been a cumbersome operation.”
Crossrail: Site constraints led to mobile hopper choice