The Severn Tunnel rail accident was a railway accident that occurred on 7 December 1991 when a

Regional Railways Regional Railways was one of the three passenger sectors of British Rail created in 1982 that existed until 1997, two years after Privatisation of British Rail. The sector was originally called ''Provincial''. Regional Railways was the most sub ...

-operated Sprinter train collided with an

InterCity 125 The InterCity 125 (originally Inter-City 125) or High Speed Train (HST) is a diesel-powered High-speed rail, high-speed passenger train built by British Rail Engineering Limited between 1975 and 1982. A total of 95 sets were produced, each com ...

in the

Severn Tunnel The Severn Tunnel () is a railway tunnel in the United Kingdom, linking South Gloucestershire in the west of England to Monmouthshire in south Wales under the estuary of the River Severn. It was constructed by the Great Western Railway (GWR) be ...

. There were no fatalities, but 185 people were injured.

Background

The

is a -long railway tunnel constructed between 1873 and 1886 to take the

South Wales Main Line The South Wales Main Line (), originally known as the London, Bristol and South Wales Direct Railway or simply as the Bristol and South Wales Direct Railway, is a branch of the Great Western Main Line in Great Britain. It diverges from the co ...

under the

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime enviro ...

of the

River Severn The River Severn (, ), at long, is the longest river in Great Britain. It is also the river with the most voluminous flow of water by far in all of England and Wales, with an average flow rate of at Apperley, Gloucestershire. It rises in t ...

. Due to water ingress, the tunnel has a pumping station which extracts of water daily.

Track circuits A track circuit is an electrical device used to prove the absence of a train on a block of rail tracks to control railway signals. An alternative to track circuits are axle counters. Principles and operation The basic principle behind the t ...

were found to be unreliable in the wet conditions, and were replaced by axle counters in 1987. Track circuits operate by sending an electric current through the rails in a given signalling section. Trains interrupt this current, which the circuits interpret as the section being occupied. Water can also interrupt the circuit, which can lead to the detection of trains where none are present. Axle counters work by counting the axles of a passing train at the entry and exit of a signalling section. If the number of axles is the same at both locations, then the train is considered to have completely left the section. The tunnel is fitted with emergency signals in each direction, which remain unlit during normal operations but turn red when activated. A tell-tale wire runs along the tunnel walls, which when broken, activates the emergency signals and triggers an alarm in the signal box. The Class 155 Sprinter train was operating 1F08, the

07:00 service from

Portsmouth Harbour Portsmouth Harbour is a / biological Site of Special Scientific Interest between Portsmouth and Gosport in Hampshire. It is a Ramsar site and a Special Protection Area. It is a large natural harbour in Hampshire, England. Geographically it ...

Cardiff Cardiff (; ) is the capital city, capital and List of urban areas in the United Kingdom, largest city of Wales. Cardiff had a population of in and forms a Principal areas of Wales, principal area officially known as the City and County of Ca ...

, with 170 occupants onboard. The

was operating 1B10, the 08:30 service from

London Paddington Paddington, also known as London Paddington, is a London railway station and London Underground station complex, located on Praed Street in the Paddington area. The site has been the London terminus of services provided by the Great Western Ra ...

to Cardiff Central, with 132 occupants onboard.

Accident

A signal failure began at around 14:00 on 6 December 1991. This meant that when the section was clear, the signaller had to manually instruct drivers to pass a signal at the tunnel entrance at danger. At around 10:20 on 7 December, the InterCity 125 approached the tunnel and stopped at the danger signal. After contacting the signaller, the train was allowed to pass the signal at danger. into the tunnel, the train was struck from behind by the Sprinter. The InterCity's brakes applied automatically and brought the train to a stand. The driver then exited the cab, broke the tell-tale wire and called the signal box using one of the tunnel's telephones. The rear power car of the InterCity had become decoupled, but both it and the rest of the train did not derail. The driver of the Sprinter was badly injured, and many of the passengers onboard had injured themselves on the seats in front of them. Two emergency trains, one from the Welsh side and the other from the English side, arrived at the accident site at least two hours after the initial impact. The more seriously injured people were removed at this time. It was at least three hours before the remaining passengers of the Sprinter were moved to the InterCity, which the driver then drove out of the tunnel towards

Severn Tunnel Junction The River Severn (, ), at long, is the longest river in Great Britain. It is also the river with the most voluminous flow of water by far in all of England and Wales, with an average flow rate of at Apperley, Gloucestershire. It rises in t ...

at . At the tunnel entrance, some injured were transferred to hospital by ambulance, with others being given first aid by doctors. It took six hours from the time of the collision to when the uninjured passengers were able to leave. In total, 185 were injured, including five seriously, but none fatally. The tunnel was reopened less than 48 hours after the crash.

Investigation

The

HM Railway Inspectorate Established in 1840, His Majesty's Railway Inspectorate (HMRI) is the organisation responsible for overseeing safety on Britain's railways and tramways. It was previously a separate non-departmental public body, but from 1990 to April 2006 it ...

under the

Health and Safety Executive The Health and Safety Executive (HSE) is a British public body responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare. It has additionally adopted a research role into occupational risks in Great B ...

carried out an investigation into the accident. The report was published in 1994, and was conducted with the assistance of the emergency services. The report could not reach a firm conclusion, but speculated that the cause was either: * an unaccountable error on the part of the Sprinter driver, or: * technicians in the relay room at

had reset the axle counter while investigating the earlier signal failure fault, thus clearing the signal for the Sprinter.

References

Train collisions in England Train collisions in Wales Railway accidents in 1991 1991 disasters in the United Kingdom Railway tunnel disasters Accidents and incidents involving British Rail December 1991 in the United Kingdom {{Rail-accident-stub