Grade crossing

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Image:Level crossing - Chertsey.jpg
Level crossing at Chertsey, England, as the barriers rise

A level crossing (British) or railroad crossing or grade crossing (American usages) is a crossing on one level, or "at grade" - without recourse to a bridge or tunnel - used to describe the crossing of a railway line by a road, path, or other railroad.

It also applies when a light rail line with separate right-of-way crosses a road; the term "metro" usually means by definition that there are no level crossings (i.e. that the system is grade-separated).

Contents

Safety

The original design for a level crossing consisted of a flagman in a nearby booth who, on the approach of a train, would race out, usually with a stopsign or red lantern and (attempt to) stop all traffic and clear the tracks. Gates, manually or electrically closable, which barricaded the roadway were later introduced. The gates were intended to be - and at the time of the design of the original crossings actually were - a complete barrier against intrusion of road traffic, vehicular or animal, onto the railway. With the appearance of motor vehicles this barrier became less and less effective, and therefore pointless; rising wage levels made the continuance of the older style crossing financially impossible. The decision was reached to substitute comparatively flimsy, but highly visible, unmanned barriers whose operation is triggered by the approach of a train but which are not linked with the railway signalling system, and to rely on road users following the associated warning signals to stop. In many cases the barrier only closes across the approach lane, and the other lane has no barrier. This is intended to allow slow vehicles unimpeded egress from a crossing whose barriers are dropping. It also, however, allows impatient drivers to zig-zag round the two half barriers to avoid any delay, and thereby provides a real potential collision risk.

In many countries, on less important roads and railway lines, level crossings are often "open" or "uncontrolled" – without gates to protect them – but these may have some kind of warning lights or bells to warn of approaching trains. Ungated crossings represent a serious safety issue; many accidents have occoured due to failure to notice or heed visual warning (the lights and bells of a crossing). Railways in the United States are adding reflectors to the side of each train car to help prevent accidents at level crossings. In some countries, such as Ireland, instead of an open crossing there may be manually operated gates, which the motorist must open and close. These too have significant risks, as they are unsafe to use without possessing a knowledge of the train timetable: motorists may be instructed to telephone the railway signaller, but may not always do so.

The consensus in contemporary railway design is to avoid the use of level crossings. The director of rail safety at the UK Railway Inspectorate commented in 2004 that "the use of level crossings contributes the greatest potential for catastrophic risk on the railways." Eighteen people were killed in the UK on level crossings in the 2003/4 period. Bridges and tunnels are favoured instead of level crossings, and there is a commitment on the part of UK rail authorities not to build new level crossings, and to reduce the number of existing level crossings from the present 8,200. However, the cost of making significant reductions, other than by simply closing the crossings, would be very substantial, and a number of commentators argue that the money could be better spent on other improvements to road safety, such as introducing grade-separated junctions on roads, rather than solely focusing on the road/rail interface. Some 6,500 of the 8,200 crossings are user-worked crossings or footpaths, with very low usage: building a bridge at each of these would be very expensive and disruptive, and not generally justified by the risks involved.

In November 2004 there were two major accidents on UK level crossings: one involved a car driver suspected of being a suicide, who caused the death of seven people (see Ufton Nervet rail crash); another involving a train carrying 50 schoolchildren resulted in no fatalities but a number of injuries. These two incidents have increased efforts to review the placing of level crossings and to eliminate them where this is reasonably practicable. In the UK it has also been suggested that cameras similar to the type used to detect drivers who run traffic lights be deployed at level crossings, and that penalties for ignoring level crossing warning lights should be much more severe than at present.

Other safety concerns compared with bridges and tunnels include access to the track itself, by vehicles, pedestrians, including children, and animals, and dangers arising from the raising and lowering of the barriers which have injured people and animals, and damaged vehicles.

Third rail electric systems may also have level crossings: there is a gap in the third rail over the level crossing, but in spite of that the power supply is not interrupted since trains have current collectors in the front and rear cars; however, care must be taken that a current or voltage gap isn't created between the two ends.

At railway stations a pedestrian level crossing is sometimes provided to allow passengers to reach other platforms in the absence of an underpass or bridge.

Crossings around the world

United States

Image:Rr crossing.jpg
US city rail crossing

In the United States, and in countries that take their railroad practice from US practice, a train must have a bright headlight, and a whistle or horn must be sounded as the train approaches the crossing. Some American cities, citing noise pollution abatement, pass laws prohibiting the sounding of bells and whistles, but their ability to enforce such rules is debatable. In December of 2003, The US Federal Railroad Administration published regulations that would create areas where train horns could be silenced, given that certain safety measures were put in place. More information can be found at the FRA website at and following the page link under 'Train horn rule.' The regulations were scheduled to go into effect in December of 2004.

Most urban grade crossings in the US have alternately flashing red lights, and a strident bell. Crossings on or near main roads also usually have gates that block the road when activated; however, US-type gates block only the roadway leading towards the tracks, and not away from them. Disused urban crossings and rural crossing often have only a crossbuck warning.

Australia

In Melbourne, Australia, there exist several level crossings where the train tracks cross tram tracks on the road. These crossings require trains to travel very slowly to avoid tangling the overhead cables.

Southeast Asia

Image:LevelCrossingPRC.jpg
Level crossing on China National Highway 109, Beijing, China

Level crossings in China, Thailand and Malaysia are still largely a manual matter. The barriers are raised using a manual switch when trains approach. A significant number of crossings are without barriers.

See Also

External links


References

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