Collapsed bridge was noticed because track was sagging

A probe has been launched by the rail accident investigation branch and first reports have revealed that a 10-foot wide hole had formed under the line and track ballast had fallen into the river below before the alarm had been raised.

Network Rail has been praised for the way it quickly rerouted the track and had trains running again last week but the extent of the damage has raised questions about the long-term safety of the 100-year-old-bridge.

The decision by the RAIB to investigate indicates the seriousness with which the rail authorities are taking the damage to the bridge as the independent group only investigates incidents which have, or could have, caused deaths, serious injuries or extensive damage to infrastructure.

The RAIB will publish a report, including any recommendations to improve safety, at the conclusion of its investigation.

Meanwhile, trains on the Feltham to Waterloo route have been running without delay for the first time this week. Lower speed limits are still imposed on the section of temporary track that runs around the damaged bridge but drivers have been able to make up the small amount of time lost during other sections of the journey.