signal turned green as a precautionary measure. After several trains had passed he went in search of a second wire with the intention of temporarily connecting the faulty signal's circuit to an unused pair of contacts on the same relay, to restore normal operation. While he was searching the collision took place just beyond Charing Cross station. Inquiry In the inquiry, the signal engineer was held wholly to blame, because although his temporary fix was reasonable under the circumstances, the instructions that he gave to the platform staff were incorrect. The holding of the train for one minute after the green aspect was reasonable, but the driver should have been instructed to, "... proceed at caution and be prepared to stop short of any obstruction". The absence of the last instruction meant that the driver would proceed at full speed and be unable to stop short of another train. Safety improvement As a result, the berth circuit (not to be confused with the berth track circuit) was developed whose purpose was to detect contacts that were closed when they shouldn't have been and to rupture the relay supply fuse if such a condition was detected forcing the controlled signals to show an unchanging danger indication. The berth circuit was retrofitted to every automatic signalling system in Britain. References "Report on the Accident between Waterloo and Charing Cross on 10 March 1938", from the Railways Archive. Accessed 1 June 2008. 1938 in London Railway accidents in 1938 March 1938 events Train collisions in England