As the inquiry into the Southall accident sat through its 32nd and final day of evidence yesterday, the bereaved pointed out that the safety system that would have prevented the Paddington tragedy in October would not have averted the disaster in which their relatives died.
One element in the 52 bundles of evidence submitted to the Southall hearing has shown that the train protection warning system (TPWS), expected to be installed on most trains in the wake of the Paddington accident, would not have prevented the collision at Southall, in which seven people died.
Unlike the more basic automatic warning system, TPWS cannot be over-ridden when a train jumps a red light. The device, seen as a short-term answer to safety problems, will bring the train to a halt, no matter what the driver does.
That would have been sufficient in the Paddington accident to stop the Thames Trains commuter service on its outward journey from the west London station before it slammed into the oncoming Great Western express, killing 31 people. SN109, the red signal passed by the local train, is far enough away from the crash site that the train would have had time to stop safely.
The Southall inquiry has heard that even with TPWS the Great Western express on its way to Paddington would still have smashed into a freight train coming towards it. The high-speed service was going too fast, and the red light was too near the point of impact.
Louise Christian, a lawyer representing those bereaved by the Southall crash, is keen that TPWS is not seen as the definitive answer to train safety. She is anxious for the point not to be lost when John Uff QC, who presides over the Southall inquiry, sits with Lord Cullen of Ashbourne, who will also chair the Paddington hearing, to consider different safety systems.
Another factor evident in the Southall inquiry was the failure of Great Western Trains and Railtrack to ensure that the fail-safe automatic train protection (ATP) system was in operation. Under ATP the speed of the train is controlled by a computer, which will slow it down at yellow lights and stop it at red - it cannot be over-ridden by the driver. ATP would have avoided both the Southall and the Paddington crashes.
Most observers think that the fundamental problem in a fragmented industry was the absence of a single authority to insist on the use of ATP.
The Southall inquiry will hear final statements from the main contributors on 20 December, and Professor Uff's report will be published next year. The Cullen hearing into the Paddington crash is to start next March, after which there will be a joint inquiry into train safety systems.