The driver of a packed northbound commuter train did not have enough distance to stop, a rail safety expert claims.
The collision on 8 August, in which one woman died and 70 other passengers were injured, took place in the evening rush hour and blocked the West Coast main line for several days.
According to the expert evidence submitted last week to David Maidment, who is chairing the Railtrack inquiry, the signalling on this stretch of line was installed in May 1992.
When the signals and adjoining junctions were put into operation, there should have been a 200-yard "overlap" - a safe zone in which trains that have overrun a signal can stop.
"The original plan would have provided a 200 yard overlap," according to the evidence. "It seems the points did not go in entirely to plan and some problems were found in re-siting the signal itself. The combined effect . . . was to reduce the overlap to 160 yards."
Another contributing factor in the Watford crash was the use of a 60 mph speed limit at the junction, which was imposed to counter the problems of the shortened stopping distance posed by allowing a "sub-standard overlap" in the first place.
"Operators in the Watford area, drivers and even instructor drivers were all totally unaware this restriction had anything to do with a reduced overlap on this signal. It was believed to have been imposed due to 'condition of track' and since no 'condition of track' existed over time, it became less and less a worry to drivers passing over it."
On a sample visit to the line, the safety expert (who cannot be named) found that a speed restriction warning was unreadable. He concluded his evidence: "To use a speed restriction to overcome a sub-standard overlap is wrong. To apply that speed restriction ineptly compounds the mistake."Reuse content