Level Crossing Protection

Compared to many other countries, the United Kingdom was slow to embrace modern methods of level crossing protection. Because the requirements for level crossings are mandated by law, new legislation was needed before alternative methods of protection could be introduced. Furthermore, level crossing development was influenced by some notable accidents that brought about revised requirements and practically halted crossing modernisation programmes while previously modernised crossings were modified.

*Note: The diagrams on these pages show typical examples of each type of crossing and illustrate the equipment that might be provided. Other crossings of the same type may differ in terms of their layout and signage. The diagrams do not necessarily reflect current requirements.*

Section 47 of the Railways Clauses Consolidation Act 1845 had mandated that level crossings on public roads must be attended and protected by gates, which were normally to be kept closed across the roadway, so as to fence the railway in. The gates were to be swung across the railway only when necessary to let road traffic across. There may be either one full gate or two half gates on each side. The gates were painted white and were often fitted with red 'targets' and red lights, both of which were visible along the road or railway depending on the position of the gates. They did not need to show along the railway if stop signals were provided. The gates were operated by hand or by a gate wheel or lever in the signal box, or occasionally by electric motor.

Fixed signals and an indication of approaching trains for the crossing attendant are required (or alternatively, a telephone to a signalman or crossing keeper with such facilities). The signals, where provided, were interlocked with the gates. In many cases, only distant signals were provided, the targets on the gates serving as stop signals. Road traffic lights were provided on busy roads. There was no restriction on the speed of trains, except that trains were at one time restricted to just 4 m.p.h. when passing over a level crossing of a turnpike road adjacent to a station.

The Road and Rail Traffic Act 1933 empowered the Ministry of Transport to permit the normal position of the gates at public road crossings to be across the railway, in certain cases. This was beneficial at those crossings where road traffic was heavy and rail traffic infrequent. Stop signals must always be provided at a crossing with gates normally closed across the railway. The 1933 Act also ended the requirement for trains to reduce speed to 4 m.p.h. when crossing a turnpike road adjacent to a station.

User worked crossings, which are unattended, can be categorised as either accommodation or occupation type. An accommodation crossing connects fields on opposite sides of the railway, while an occupation crossing is for a private vehicular road. The user-worked gates open away from the railway so that they do not foul the line if left open. Whistle boards may be installed so that crossing users have better warning of an approaching train. Telephones connected to the nearest signal box may be provided. A speed restriction for trains may be imposed if sighting is poor and telephones are not provided.

Another type of unattended level crossing is the "Trainman Operated Crossing" (TMO). The gates are normally closed across the railway and are opened and closed by the traincrew. A distant signal fixed at 'caution', or a suitably worded notice board, is provided on each rail approach. Stop boards may be provided at the crossing. A TMO crossing is suitable only for use on lightly used railways.

The British Transport Commission Act 1954 allowed level crossings on public roads to be protected by lifting barriers instead of gates. The barriers, when lowered, close off the full width of the roadway. This can be achieved either by one full-length barrier or by two half-barriers on each side of the railway. The requirement that the crossing be attended remained but barriers brought a small improvement in road closure time in comparison to gates. Some crossings are provided with road traffic signals comprising two horizontal red lights that flash alternately as an instruction to stop. Barrier auto-lower and/or auto-raise facilities may be provided. Once the barriers are down, the protecting railway signals cannot be cleared until the operator presses a 'crossing clear' button to verify that the crossing is unobstructed. Lifting barriers had first been trialled in 1952 at Warthill, on the now closed direct line between York and Hull.

    Subject to certain conditions, a manually controlled barrier crossing may be located remote from the point of operation, up to a maximum distance of a quarter mile (400 metres). The operator must have a clear view of the crossing in normal weather conditions. Road traffic signals and telephones must always be provided at a remotely controlled crossing.

Driven by the desire to reduce delays to road traffic, a British Railways / Ministry of Transport joint working party was formed in 1956 to look at methods of level crossing protection employed in France, Belgium and the Netherlands. As a consequence of its findings, the British Transport Commission Act 1957 permitted the use of automatic half-barriers for the first time, and the requirements for "Automatic Half Barrier" (AHB) crossings were published in 1958. The 'half-barriers' only close off the road to oncoming traffic. The other side of the road is left unobstructed so as not to block the exit of any road vehicle on the crossing. Automatic crossings are not interlocked with railway signals. Maximum speed for trains was initially restricted to 60 m.p.h. but has since been raised to 100 m.p.h. The first AHB was commissioned at Spath on the now closed line between Leek and Uttoxeter, in 1961. The crossing is supposed to be monitored by a signaller by a indication panel.

    At open crossings with flashing lights (designated "Automatic Open Crossing, Locally Monitored" (AOCL) from 1981), an indicator in the form of a white light is provided on each rail approach to confirm to train drivers the correct operation of the road traffic signals. The driver must check its indication on passing the speed restriction board. The train may then proceed over the crossing provided it is not obstructed. The maximum permitted speed for trains is no more than 55 m.p.h. Differential speed restrictions apply at some crossings. The first AOCL was commissioned at Yafforth on the Wensleydale branch, in 1963. An at AOCL where trains are required to stop, the driver may have to press a plunger to initiate the crossing sequence.

At open crossings where trains are required to stop before the crossing, there are no speed restriction signs but stop boards (and 'advance stop boards') are provided. The stop board instructs the driver to sound the whistle before proceeding. Note that trains may be required to stop in one direction or both directions depending on the circumstances at a particular level crossing.

Some level crossings have neither gates nor barriers. These 'open' crossings were initially restricted to use on single track railways. Some simply have "give way" signs to warn road traffic, while others have road traffic signals. At open level crossings where trains were not required to stop, a combined speed restriction and whistle board was erected displaying the speed to be observed approaching the crossing. On passing the speed board, the driver must ascertain that the crossing is unobstructed. Train movements are restricted to 10 m.p.h. over an open crossing without lights.

    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.

A TMO crossing may be protected by lifting barriers instead of gates. Stop boards (and 'advance stop boards') are provided, instructing the driver to operate the barriers. 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 and the barriers have to be raised manually.

Through 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 located at the crossing lets the signalman or crossing keeper observe the crossing on a monitor 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 around 1971, following a trial in 1970 at Funtham's Lane near Peterborough. There is no restriction on the speed of trains.

In 1976, a B.R./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 m.p.h. 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 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.

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 would fill 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 m.p.h. The first ABCL to be commissioned was at Beccles By-Pass on the East Suffolk Line in 1988.

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. A trial of this system took place in 2010 at Filey. There is no restriction on the speed of trains.