On 27 December 2014, and again on 28 December 2014, track workers were at serious risk of being struck by trains at the Stockley Flyover construction site, on the Heathrow Airport branch line. In the second incident, a train did collide with a small trolley which was being placed on the line by track workers.
During the first incident, 14 track workers walked along the open Down Airport line; an area where limited visibility meant that it was unsafe to do this when train services were operating. They mistakenly believed that train services had been stopped. A Heathrow Airport to London service used the line shortly after the workgroup had been warned by other staff and had moved clear. The investigation found that an inappropriate system was used to control access to the track, permitting trains to start operating when track workers could reasonably believe services remained suspended. Staff had also been directed to walk along a line when paperwork showed it was open to traffic.
The following day, two track workers were placing a small trolley on the Up Airport line when a train emerged from a nearby tunnel at a speed of 45 mph (72 km/h). The track workers moved clear of the line seconds before the train struck the trolley. There were no injuries and only minor damage. The track workers believed the line was closed, a consequence of being accustomed to working in a way which differed from the mandated site safety system.
The two incidents, and other safety shortcomings found, showed that site supervision processes had not identified that deviation from the mandated site safety system had become normal practice. Also, formalised briefings had not been supplemented by any site signage to increase the likelihood of staff being aware of which lines were open.
RAIB has made four recommendations, all addressed to Network Rail with some also seeking input from major contractors. The first seeks an improvement in monitoring of railway safety arrangements on major construction site. The second relates to effective monitoring of staff controlling access to worksites. The third seeks to provide workers on major construction sites with additional sources of information about the lines on which it is safe to work. The final recommendation seeks a review, and if necessary improvement, of the railway access control systems used on large construction sites.
Three learning points are included to remind engineering supervisors and COSSs that they should comply with safety requirements and query any safety related anomalies in their paperwork. There are two other learning points made which are not directly related to the incidents: a reminder to employers that they should ensure that their staff have received railway rule book updates; and a reminder to those preparing site safety paperwork to make it comprehensive, but concise.
Response to recommendations:
- RAIB will periodically update the status of recommendations as reported to us by the relevant safety authority or public body
- RAIB may add comment, particularly if we have concerns regarding these responses.