It is a myth that moving block signalling never works (NCE 11 November). The original Docklands Light Railway signalling system did not perform reliably, but this was actually automated fixed block. It was not designed to meet even the demand created by phase one of the Canary Wharf project. The replacement SELTRAC system, installed during 1990-1993, uses the moving block concept and has performed well.
Vancouver Skytrain was probably the first large scale application of moving block signalling. It has worked well since it was commissioned in late 1985.
For some reason, London Underground decided to split the contract for the Jubilee Extension's moving block control system between three contractors. This seems a bit like trying to hook a Macintosh printer to a PC, and run Unix on it. No wonder it did not work.
Railtrack has been committed to moving block on the West Coast Main Line since the modernisation study in 1994-5. It would be a great setback for the railway industry, and to the railway's customers, if they were to abandon it now.Michael Schabas, Director, GB Railways firstname.lastname@example.org