A passenger train that later became involved in a fatal rear-end collision had stopped after receiving an incorrect Automatic Warning System alert at a green signal, according to an interim report from Britain’s Rail Accident Investigation Branch.
The June 19 collision involved two East Midlands Railway trains on the Midland Main Line about 2.5 miles south of Bedford. The driver of train 1H46, traveling from Corby to London St Pancras, was killed when it struck the rear of stationary train 1B67, a Nottingham-London St Pancras service. RAIB has identified 257 people aboard the two trains, at least 160 of whom were injured. Both trains derailed.
Train 1B67 was traveling at about 123 mph when its AWS equipment generated a warning while signal WH154 displayed green. The warning was not acknowledged within the required 2.7 seconds, triggering an automatic emergency brake application. The train stopped shortly afterward, causing WH154 behind it to display red to protect the occupied section.
Investigators found that neither the driver nor the driving instructor aboard 1B67 recognized the continuing alarm as an AWS warning.
Train 1H46 subsequently approached WH154, acknowledged an AWS warning associated with the red signal but continued accelerating. It passed the signal at danger and eventually reached 76 mph. The driver applied full-service braking about 10 seconds before the collision and emergency braking about two seconds later. The train struck 1B67 at about 50 mph.
Signal WH154 was not equipped with Train Protection and Warning System equipment or a signal-passed-at-danger alarm. RAIB noted that regulations did not require TPWS at the signal under circumstances involving the risk of a rear-end collision between trains traveling in the same direction.
A later incident on July 9 involved another Class 810 train receiving an incorrect AWS warning at WH154 while the signal was green. Subsequent examination found the AWS electromagnet positioned 16 millimeters below railhead level, outside the required tolerance of plus or minus 12 millimeters. Investigators are continuing to examine how that equipment interacted with train 1B67.
RAIB stressed that its investigation remains ongoing and has not yet determined why train 1H46 passed the red signal.
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