RAIB Issues Safety Digest After Overspeeding Incident at Cambridge Junction

An overspeeding incident involving a Great Northern passenger service occurred at Cambridge Junction in December, prompting the Rail Accident Investigation Branch to publish a safety digest rather than launch a full investigation.

The incident happened at 10:39 on 11 December 2025 and involved train reporting number 1T20, the 10:12 service from London Kings Cross to Ely, operated by Great Northern, a trading name of Govia Thameslink Railway Ltd. As the train approached Cambridge Junction, it was routed from the Down Slow line onto a diverging route over a set of points subject to a permanent speed restriction of 25 mph.

CCTV evidence confirmed that the signalling system was displaying the correct aspects for the diverging route. Despite this, the train passed over the points at a speed of 56 mph. The excessive speed caused the train to lurch sideways, resulting in several passengers being thrown from their seats. The permitted speed for trains continuing straight on the Down Slow line at that location is 75 mph.

No injuries were reported and the train and infrastructure were not damaged. However, the circumstances raised safety concerns due to the significant exceedance of the permitted speed over the junction.

RAIB carried out a preliminary examination into the event and also reviewed two similar overspeeding incidents at Grantham South Junction on 25 February and 26 September 2025. In addition, it considered the findings of two earlier investigations into overspeeding at Spital Junction in Peterborough in April 2022 and May 2023.

As recommendations from those previous investigations remain open, RAIB has chosen to issue a safety digest for the Cambridge Junction incident, drawing together the evidence and reinforcing existing safety lessons rather than beginning a separate full investigation.

Image: RAIB