The Rail Accident and Investigation Branch (RAIB) is investigating after a track worker was hit by a train earlier this month.
The incident happened at 09:31 on Friday, 15 April near Chalfont & Latimer station, Buckinghamshire.
The track worker sustained injuries that needed hospital attention.
RAIB says the train involved was a London Underground Metropolitan line service from Baker Street to Chesham. It was moving at 25 miles per hour on a section which allows trains to run both directions and has a maximum speed of 35 miles per hour.
There are two other lines at the same location.
The track worker was one of three who were carrying out a scheduled track inspection. This was set to go ahead when lines were open to traffic, but in a way that was intended to keep staff clear of moving trains.
RAIB’s investigation will seek to establish the sequence of events leading to the accident. It will include consideration of:
- the actions of those involved
- the planned system of work
- the arrangements in place for planning work where lines are open to traffic
- the management of the competence of track workers
- any relevant underlying factors.