Rail Accident Investigation Branch
On the morning of Thursday 31st December 2015, several trains passed over Lamington Viaduct after the ground beneath a viaduct pier had been eroded by river scour. The viaduct carries the railway, running between Carstairs and Lockerbie, across the River Clyde. This is a section of the West Coast Main Line between Glasgow and London where passenger trains are permitted to travel at up to 120 mph (193 km/h). Although there were no injuries or damage to trains, the viaduct was seriously damaged, and the main line is expected to remain closed until March 2016 while it is repaired.
At 07:35 hrs, the driver of the southbound 06:52 Virgin West Coast service from Edinburgh Waverley to London Euston reported a dip in the track and, in response, signallers restricted the speed of trains until track maintenance staff had arrived on site. After inspecting the track and watching a southbound train pass at low speed, the track maintenance staff attending removed the speed restriction. They remained on site to undertake minor remedial work. After observing unusual track movement at 08:40 hrs, during the passage of the northbound 05:57 hrs Virgin West Coast service from Crewe to Glasgow Central at high speed, they immediately re-imposed temporary speed restrictions on trains in both directions. They blocked the line to all trains a few minutes later at 08:53 hrs after observing a large crack in pier number 2, one of three viaduct piers located in the river.
Subsequent investigation has revealed a large hole beneath pier number 2, subsidence of the pier and damage to three of the steel bearings which support the bridge deck. The damage was discovered following exceptionally high water levels, and fast flows in the River Clyde due to Storm Frank, which impacted the UK on 29 - 30 December 2015. On 10 January 2016, after the viaduct had been closed, a disused part of pier number 3 collapsed.
Our investigation will include examination of:
- actions in response to a scour risk assessment undertaken for Lamington Viaduct in 2005
- actions taken when the approach of Storm Frank resulted in warnings of exceptionally heavy rain, likely to cause fast flow in the River Clyde
- responses to the 31 December report of a track dip on the viaduct
- the effectiveness of Network Rails processes intended to mitigate risks to structures, including scour related risks, due to extreme weather
- any underlying management factors.
Our investigation is independent of any investigation by the railway industry or by the industrys regulator, the Office of Rail and Road.
We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website.
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