Home Page > Supplementary Information > Level Crossing Protection; pages: 1, 2
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 mph 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 mph when crossing a turnpike road adjacent to a station.
|Fig. 1: Manually Worked Gates.|
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 to give crossing users 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.
|Fig. 2: User-Worked Crossing (UWC).|
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.
|Fig. 3: Trainman Operated Crossing (TMO).|
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, having verified by sight that the crossing is unobstructed. Lifting barriers had first been trialled in September 1952 at Warthill, on the now closed direct line between York and Hull.
|Fig. 4: Manually Controlled Barriers (MCB).|
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 (0.4 km). 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.
|Fig. 5: Manually Controlled Barriers, Remotely Controlled (RC).|
In certain circumstances, and provided that road traffic was light, it was possible to locate a manually controlled barrier crossing out of sight of the operator. These barriers were referred to as "On Call" barriers, and they normally remained lowered across the roadway. A road user arriving at the crossing pressed a plunger to request the operator to raise the barriers. After a set period of time had elapsed, the barriers automatically returned to the lowered position. Telephones were provided at the crossing, but road traffic signals were not necessary. Protecting railway signals were not necessary on lines worked by the Absolute Block system if the level crossing was interlocked with the block.
|Fig. 6: "On Call" Barriers.|
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 result 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 mph, but this has since been raised to 100 mph. The first AHB was commissioned at Spath on the now closed line between Leek and Uttoxeter, in February 1961.
|Fig. 7: Automatic Half Barrier Crossing (AHB).|
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. A notice board or advance warning board is located on each rail approach, at full braking distance to the crossing. 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 mph over an open crossing without lights.
|Fig. 8: Open Crossing without lights (OC).|
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 mph. Differential speed restrictions apply at some crossings. The first AOCL was commissioned at Yafforth on the Wensleydale branch, in September 1963.
|Fig. 9: Open Crossing with flashing lights (AOCL).|
At open crossings where trains are required to stop before the crossing, there are no speed restriction signs but stop boards are provided. The stop board instructs the driver to sound the whistle before proceeding. At one time, the stop boards were preceded by 'advance stop boards' / 'intermediate boards'. Note that trains may be required to stop in one direction or both directions depending on the circumstances at a particular level crossing.
|Fig. 10: Open Crossing without lights (OC).|
An at AOCL where trains are required to stop, the driver may have to press a plunger to initiate the crossing sequence.
|Fig. 11: Open Crossing with flashing lights (AOCL).|