Level Crossing Protection

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By 1964, some user-worked crossings on roads of a local nature (usually private roads) or heavily used footpath or bridleway crossings were being provided with miniature red/green warning lights on both sides of the railway. Normally a steady green light is displayed, which changes to red on the approach of a train. Crossings on private roads are protected either by gates that open away from the railway or by rural barriers. Rural barriers are user-operated and arranged such that both barriers can be raised or lowered simultaneously. Whistle boards may be installed, and there may be telephones connected to the nearest signal box. There is no restriction on the speed of trains.

Fig. 12: Miniature Red/Green Warning Lights (R/G).

On 6 January 1968, a serious collision occurred at an AHB crossing at Hixon in Staffordshire, killing eleven people. The report into the collision recommended increasing the warning time given to road users at AHB crossings, and it also recommended that the flashing red lights in the road traffic signals be preceded by a steady amber light. In 1970, it was agreed with the Ministry of Transport that amber lights would be provided at all types of crossings with road traffic signals. The MoT issued new requirements for AHB crossings in 1971, incorporating the recommendations of the Hixon report.

A TMO crossing may be protected by lifting barriers instead of gates. Stop boards are provided, instructing the driver to operate the barriers. 'Advance stop boards' / 'intermediate boards' may also be provided. The barriers are lowered by operating a plunger or similar. A flashing white light indicates to the train driver that the barriers have been lowered across the road. At some crossings, the barriers rise automatically after the train has passed. Beyond the crossing, a "barriers up" indicator may be provided to advise the driver that the barriers have risen. If the indicator has not illuminated by the time the train is about to pass it, the train must stop to allow a member of traincrew to return to the crossing to raise the barriers using the control unit.

Fig. 13: Trainman Operated Crossing with Barriers (TMOB).

With the use of closed-circuit television (CCTV), it became feasible for manually controlled barriers to be operated from a signal box or gate box located many miles away. A CCTV camera situated at the crossing sends video images to a monitor, which lets the signalman or crossing keeper observe the crossing and check that it is unobstructed before allowing a train across. Road traffic signals and telephones must always be provided at a CCTV monitored crossing. Surveillance of level crossings by CCTV began in 1971, following a trial in 1970 at Funthams Lane near Peterborough. There is no restriction on the speed of trains.

Fig. 14: Manually Controlled Barriers monitored by Closed-Circuit Television (CCTV).

In 1976, a BR/DoT joint working party recommended a new type of crossing to fill the gap in the range of crossing protection between an AOCL and an AHB. This was to be the "Automatic Open Crossing, Remotely Monitored" (AOCR), which is essentially an AHB without barriers. The maximum permitted speed for trains is no more than 75 mph. The new requirements were produced in 1978. From the point of view of road users, an AOCR appears the same as an AOCL but with telephones. The first AOCR was commissioned in May 1983 at Naas on the Gloucester to Newport line, that crossing formerly having been provided with miniature red/green lights when a fatal collision occurred there on 1 March 1979.

Fig. 15: Automatic Open Crossing, Remotely Monitored (AOCR).

On 26 July 1986, a collision occurred on an AOCR at Lockington on the Hull to Scarborough line, killing nine people. This led to a review of automatic open level crossings (AOCLs and AOCRs) being undertaken by Professor P F Stott. The Stott report concluded that no more AOCRs should be installed and that those already in existence should be converted to AOCLs or AHBs. As it happened, a new kind of level crossing known as "Automatic Barrier Crossing, Locally Monitored" (ABCL) was introduced. The ABCL filled the gap in available protection methods between an AOCL and an AHB that was created by the demise of the AOCR. The ABCL is essentially an AOCL equipped with half barriers. From the point of view of road users, an ABCL appears the same as an AHB. Telephones are usually provided. When the driver's white light is not flashing, a flashing red light is displayed. The maximum permitted speed for trains is no more than 55 mph. The first ABCL to be commissioned was at Beccles By-Pass on the East Suffolk Line, in 1988.

Fig. 16: Automatic Barrier Crossing, Locally Monitored (ABCL).

Trains may be required to stop before proceeding over the crossing, in one or both directions.

Fig. 17: Automatic Barrier Crossing, Locally Monitored (ABCL).

As an alternative to CCTV surveillance of a level crossing with full barriers, an obstacle detector may be provided. This, together with barrier auto-lower and auto-raise provision, allows the crossing to operate fully automatically. The obstacle detector, which is situated in one corner of the crossing, uses radar (which may be complemented by lidar) to verify that the crossing is unobstructed. The crossing area is scanned both before and after the exit (offside) barriers descend, confirming that the crossing is clear before a train may be signalled across. Road traffic signals and telephones for public use are always provided. A trial of this system took place in 2009/2010 at Filey. There is no restriction on the speed of trains.

Fig. 18: Manually Controlled Barriers with Obstacle Detector (MCB-OD).

Following a fatal collision at an AOCL at Halkirk on 29 September 2009, the Rail Accident Investigation Branch carried out an investigation into the safety of AOCL crossings and recommended installing barriers at some of them. In response to this, Network Rail developed a cost-effective method of retrofitting half barriers to an AOCL crossing without the high cost of full conversion to ABCL. This resulted in a new crossing type referred to as an AOCL+B (AOCL plus barriers), which has a similar appearance to an ABCL (see figures 16 and 17) from the point of view of both road users and train drivers. The first AOCL to be converted to an AOCL+B was at Ardrossan Harbour, in April 2012.

An "Automatic Full Barrier Crossing, Locally Monitored" (AFBCL) is an enhanced form of ABCL, provided with full barriers. This is intended for locally monitored crossings with a high level of misuse by pedestrians, or a risk of misuse. The exit (offside) barriers will not descend unless the crossing is proved clear of pedestrians by lidar. Telephones for the public need not be provided. The first crossing to be converted to an AFBCL was at Princes Street, Ardrossan, in January 2018.

Fig. 19: Automatic Full Barrier Crossing, Locally Monitored (AFBCL).

Trains may be required to stop before proceeding over the crossing, in one or both directions.

Fig. 20: Automatic Full Barrier Crossing, Locally Monitored (AFBCL).