Causes
The immediate cause of the accident was that the signalman forgot that he had moved the two light engines to the down line, waiting there to proceed to Carlisle. He later improperly cleared the down line signals without ascertaining that the line was clear.
In the sequence of events as related in "Red for Danger", the driver of another light engine waiting to return south to Leeds saw the two northbound light engines move off when the starting signal was cleared. The signal did not return to danger, and the express passed through shortly afterwards. The driver went to the signalbox and related what he had seen. Signalman Sutton refused to believe him until he had checked his train register, and then telephoned the signal box at Ais Gill to the north to ask whether the two light engines had gone through. The Ais Gill signalman replied that none had been offered to him; nor had the express passed. Sutton then asked Signalman Simpson, who was about to relieve him and had just come into the signal box, to "Go to Bunce and tell him I am afraid I have wrecked the Scotch Express". It is apparent from this account that Sutton had been under the mistaken impression that he had despatched the two light engines to Carlisle some time earlier.
Although the signalman naturally bore the chief blame for the accident, the drivers of the light engines were also at fault for failing to carry out Rule 55 which was designed to remind signalmen in this situation. Under this rule, they should have sounded their engine whistles on coming to a stop, and when the signal was not cleared, they should have sent one of the firemen to walk to the signalbox to remind the signalman personally. In 1910, the time after which this should be done was not specified, but was generally accepted to be two or three minutes. The engines were actually detained for twenty minutes. Nock states that ten minutes was allowed, but does not give a source for this.
The two light engine drivers (Scott and Bath) stated that they had sounded their whistles as they moved off, and this was confirmed by the driver of the engine waiting to return to Leeds. The signalman had not been alerted by this, probably because driving rain was being blown against the windows of the signalbox, making it hard to hear sounds outside, and because other engines were moving around the station and yard at the same time, so that the signalman would not have attached any particular significance to a train whistle.
Many railways had adopted reminder appliances, simple mechanical collars that the signalmen were required to place on signal levers, as a back-up to prevent improper clearance of signals. The Midland Railway had not adopted these simple devices.
The accident would have been prevented if track circuits had been installed to detect the presence of a train (or in this case the light engines) on the main lines, and interlocking with the signals would have prevented them being cleared by the signalman. Track circuits had been invented in the 1870s and had proved to be very successful; unfortunately most British railway companies were slow to install them. The high level of traffic movements made Hawes Junction a prime location for their installation. The Board of Trade accident report unequivocally recommended this, and the Midland Railway rapidly complied both here and at 900 other locations on their network.
The issue arose of whether the signalman was overworked. The Midland Railway had a policy of using small engines only, and on the steeply-graded Settle and Carlisle line, this required frequent double-heading (two locomotives coupled together to operate a single train) or the use of pilot engines to assist engines in pulling trains up to Ais Gill at the summit of the line. Double-heading would not increase the amount of traffic, but pilot engines detached at Ais Gill would usually proceed to Hawes Junction where there was a turntable, to be turned and marshalled together to return to their sheds at Carlisle (or Leeds). These light engine movements would naturally increase the total amount of traffic at Hawes Junction, but the Railway Inspectorate report specifically rejected the assertion that overwork was a factor. However, between moving the two light engines onto the down line and accepting the express, the signalman had to deal with two up goods trains and several up light engines, movements which would require all his concentration to avoid delay, and make it easy to forget about the down line.
Read more about this topic: Hawes Junction Rail Crash