The investigation has been hampered by the absence of a usable tape in the recording device on the northbound commuter service which went through a red light before hitting an empty southbound train. The tape was found by the investigators to be blank because of faulty maintenance.
The lack of the tape, which would have recorded data on speed, brakes and signals, is an embarrassment to the rail industry as the recorders' installation was a key recommendation of the Hidden inquiry into the 1988 Clapham rail disaster and this was the first crash in which it would have provided definitive evidence.
One theory is that the train driver suffered a blackout, and only became aware of a problem when he saw the red light. He slammed on the brakes but because there is a shorter than usual distance between the signal and the points which it is supposed to protect, he collided with the up train.
Publication of the report, by safety consultant David Maidment who retired from Railtrack last year, has been postponed, possibly until the end of the month, while Railtrack considers its response.
Mr Maidment's report will say that the decision in 1992 to create the short overlap after the signal - 160 yards instead of 200 - was made because of technical difficulties, as the signal is so near a bend, rather than to save the pounds 200,000 cost of moving gantries. The rail unions will argue that it was primarily the cost which led to the decision.
The report is thought to be highly critical of the fact that drivers were not informed of the 60mph speed limit imposed as a result of the short overlap.
The accident would have been prevented by the installation of Automatic Train Protection, another recommendation of the Hidden inquiry. However, British Rail and the Government refused to install it because the pounds 400m cost was not thought to have been worthwhile as it would only have saved around 30 lives over the lifetime of the system and it was felt the money would be better spent on more cost-effective safety measures.Reuse content