On 7 December 1991, two trains collided inside the
Severn Tunnel
The Severn Tunnel ( cy, Twnnel Hafren) 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 ...
, between England and Wales. There were no fatalities but 185 passengers were injured.
Accident
The 08:30
London Paddington
Paddington, also known as London Paddington, is a London station group, Central London railway terminus and London Underground station complex, located on Praed Street in the Paddington area. The site has been the London terminus of services pro ...
to
Cardiff Central operated by an
was stopped at a signal guarding the entrance to the Severn Tunnel. On telephoning the
signalman
A signalman is a person who historically made signals using flags and light. In modern times, the role of signalmen has evolved and now usually uses electronic communication equipment. Signalmen usually work in rail transport networks, armed for ...
according to
Rule 55
Rule 55 was an operating rule which applied on British railways in the 19th and 20th centuries. It was superseded by the modular rulebook following re- privatisation of the railways. It survives, very differently named: the driver of a train wai ...
, the driver was advised of a signal failure and given permission to proceed slowly at caution. Three miles into the tunnel, the train was struck from behind by a
Class 155 ''Sprinter'' travelling from
Portsmouth
Portsmouth ( ) is a port and city in the ceremonial county of Hampshire in southern England. The city of Portsmouth has been a unitary authority since 1 April 1997 and is administered by Portsmouth City Council.
Portsmouth is the most dens ...
to Cardiff. 185 passengers were injured, including five seriously, but none fatally.
Because
track circuit
A track circuit is an electrical device used to prove the absence of a train on rail tracks to signallers and control relevant signals. An alternative to track circuits are axle counters.
Principles and operation
The basic principle behind t ...
s were unreliable in the unusually wet tunnel environment (10 to 20 million gallons of water are pumped out per day),
axle counter
An axle counter is a system used in railway signalling to detect the clear or occupied status of a section of track between two points. The system generally consists of a wheel sensor (one for each end of the section) and an evaluation unit for c ...
s were used instead. The official report into the accident
[ 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 Severn Tunnel Junction 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
Tunnel disasters
Accidents and incidents involving British Rail
December 1991 events in the United Kingdom
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