Six trains exceeded Aberdeenshire reduced speed limit
RAIBSix trains exceeded a reduced speed limit in place because of a forecast of heavy rain, a report has said.
The incidents happened in a 40mph emergency limit between Laurencekirk and Portlethen on 4 December last year.
Some trains reached the normal maximum permitted speeds which varied along that length of line up to 100mph.
The Rail Accident Investigation Branch (RAIB) said more needed to be done to ensure drivers were fully informed of emergency restrictions.
The investigation found that some drivers were unaware of the blanket emergency speed restriction (BESR) as they approached it, and others were unaware of its exact extent.
However, the RAIB said the actual amount of rainfall was not sufficient to cause any earthwork failures, and there were no accidents.
The RAIB concluded that the industry had more work to do to establish a suitable method for the imposition of speed restrictions in response to extreme weather that had the potential to endanger infrastructure.
'Processes were ineffective'
Its first recommendation seeks an improvement to the BESR notices provided to drivers, and the second seeks a review of the methods used to implement blanket emergency speed restrictions.
Simon French, chief inspector of rail accidents, expressed concern at the number of overspeeding incidents at speed restrictions on the mainline network.
He said: "This report highlights some of the causes of overspeeding. It shows how important it is to convey information to train drivers about emergency speed restrictions in a way that they can understand and retain."
He added: "In this case the industry's processes were ineffective, and it is fortunate that the weather was not as bad as feared and that no accident occurred."