Clayton Tunnel is a railway tunnel located near the village of Clayton

Clayton, West Sussex

Clayton is a small village at the foot of the South Downs in the Mid Sussex district of West Sussex, England. It lies south of London, north of Brighton, and east northeast of the county town of Chichester. Other nearby towns include Burgess Hill to the north and Lewes, the county town of East...

, West Sussex

West Sussex

West Sussex is a county in the south of England, bordering onto East Sussex , Hampshire and Surrey. The county of Sussex has been divided into East and West since the 12th century, and obtained separate county councils in 1888, but it remained a single ceremonial county until 1974 and the coming...

 between Hassocks

Hassocks railway station

Hassocks railway station serves Hassocks in West Sussex. It is on the Brighton Main Line and Thameslink 12 km north of Brighton railway station, and train services are provided by Southern and First Capital Connect.-History:...

 and Preston Park

Preston Park railway station

Preston Park railway station serves the northern suburban areas of Brighton in East Sussex, England. It is on the Brighton Main Line and Thameslink 2 km north of Brighton railway station, and train services are provided by Southern and First Capital Connect...

 railway stations on the Brighton Main Line

Brighton Main Line

The Brighton Main Line is a British railway line from London Victoria and London Bridge to Brighton. It is about 50 miles long, and is electrified throughout. Trains are operated by Southern, First Capital Connect, and Gatwick Express, now part of Southern.-Original proposals:There were no fewer...

. At 1 mile 499 yards (approximately 2066 metre) it is the longest tunnel on the route.

Another tunnel of the same name is found on The Queensbury Lines

The Queensbury Lines

The Queensbury Lines were part of the Great Northern Railway in West Yorkshire, England. They opened in 1882 and closed in 1955, however goods trains continued to run until 1974 between Bradford Exchange and Horton Park Station....

, a disused route between Queensbury and Bradford at 53.7763°N 1.8314°W.

Accident

The West Sussex tunnel was the site of an early form of "automatic" signal invented by CF Whitworth. Far from being fully "automatic" in operation, this was merely a signal that was operated by the signalman

Signalman (rail)

A signalman or signaller is an employee of a railway transport network who operates the points and signals from a signal box in order to control the movement of trains.- History :...

 on duty but returned to 'danger' once the train had passed, by means of a treadle

Treadle (railway)

In railway signalling, a treadle is a mechanical or electrical device that detects that a train axle has passed a particular location. They are used where a track circuit requires re-inforcing with additional information about a train's location, such as around an automatic level crossing, or in an...

. There was one of these at each end of Clayton Tunnel, and it was the failure of the signalman to ensure that the signal had returned to danger that led to the worst ever accident on that line on 25 August 1861.

Three trains left Brighton within a very short time. Having signalled one train correctly, a signalman at the southern portal manually returned the signal to danger too late for the second train, but was unaware that his attempts to alert its driver by waving a flag were successful. The second train stopped well inside the tunnel, and as it was slowly reversing towards him he misunderstood a 'tunnel clear' message from the north box as indicating the second train had cleared the tunnel when it in fact referred to the first. He then allowed a third to enter and collide with the reversing second train with the loss of 23 lives and 176 injured.

External links

• Clayton Tunnel North Portal
• Clayton Tunnel on Trainspots