Definitions

emergency brake

Emergency brake (train)

In trains, control of Emergency brakes is made available to the travelling passengers. Activating the brake will cause the train to automatically stop. Severe fines are often in place to dissuade people from activating the brake without good reason.

Several different types of control interfaces are available for the emergency brake. In the passenger cabins of trains operating in New York State, the emergency brake is usually a cord that the passengers may pull to activate. In the cabs of light rail cars and European mainline trains, the emergency brake is often a 'big red button', which the train crew refer to as the 'mushroom'. In light rail cars this also activates the magnetic track brakes. In traditional U.S. commuter rail cars, the handbrake is a large wheel which takes considerable force to turn. Although all are emergency brakes, the mechanism of operation can differ depending on the railcar design.

Use in the UK

This type of equipment was introduced to the United Kingdom by the Regulation of Railways Act 1868. Section 22 stated that "All trains travelling a distance of more than 20 miles without stopping are to be provided with a means of communication between the passengers and the servants of the company in charge of the train." At first, this means of communication was a cord running down the length of the train at roof level outside the carriages, connected to a bell on the locomotive. When the use of the automatic brakes was made compulsory in the Regulation of Railways Act 1889, the equipment was modified so that it operated the brakes, but the name communication cord has survived to the present day. Up until the 1970s, a "chord" (although by that time it was chain) was still used. This ran the length of the carriage and connected to a valve at one end which opened the brake pipe. A butterfly valve on the side of the carriage was used to reset, and also made it easy for the train crew to see in which coach the cord had been pulled. Later designs switched to handles which were pulled down to operate, and more recent types use buttons usually connected to a PassComm system (see below). On many modern types with sliding doors, the BIL - Body Interlock Light - usually used to show doors on a carriage are open, will flash to show when the brake has been used.

Override

In most rolling stock built since the 1980s, passenger communication handles (PassComms) have been installed. When a PassComm is activated, an alarm activates in the driver's cab. If the driver decides the train is not in a safe place (i.e. in a tunnel, or on an overbridge) he will override the alarm. For this he has around 3 seconds to press an override button, otherwise the brakes automatically apply. The driver can also speak to the person who pulled the handle via a speaker/microphone mounted alongside the handle. On modern trains this is particularly useful since due to accessibility regulations the passcomm must be much easier to use and more accessible, making accidental as well as deliberate activation much easier. On some modern trains the passcomm in the accessible toilet is mounted such that it is often confused with the door or flush control leading to accidental activation.

London Underground

When London Underground began converting trains for one person operation during the 1970s and 1980s, the original emergency brake systems were replaced by an alarm and a passenger communication system. On earlier systems the brakes were not applied automatically, this being under the control of the driver, whereas later systems have an override as above. Marker boards showing an exclamation mark were provided on departure from each station at the point where the rear of the train would no longer be in the platform. Normally if the alarm was activated before the board the driver would stop the train, whereas if it was afterwards they would continue to the next station. Later, these boards were replaced by a number of boards counting up the number of cars that are beyond the end of the platform, for example on a line with 6 car trains these show 1, 2, 3, 4, 5, 6. When a train has stopped these help the driver to see how much of the train is in the platform and along with communication with the passenger, and if available station staff, to decide whether to deal with the situation with the train as it is, continue to the next station, or possibly reverse back into the station (after consultation with line controllers and with proper safety measure). During hot summers passengers are warned against using the emergency alarms if feeling unwell, since this can cause delays to the train as well as other trains and increase the problem. If feeling unwell, passengers are instead instructed to leave the train at the next station and get fresh air or a cold drink.

Russian trains

In Russian trains there is usually emergency brake known as "stop crane" (стоп-кран). In elektrichkas stop-crane usually located near train doors and sometimes in the middle of wagon as well. Trains usually have "stop cranes" near the doors as well and some wagons may also have stop crane in the middle of wagon. Stop crane usually looks like very specific red handle. Using this handle by turning it down, counter-clockwise by 90 degrees or so usually causes usual pneumatic (air) brakes to engage due to air pressure loss in standard air braking system, therefore it's usually real air crane. While being primitive and not allowing any override, such system is very effective, resembles usual train braking by air brakes and does not tends to fail in emergency conditions like fire or partial derailment while more complicated systems may disallow quick braking even when really needed or communication could fail in emergency scenario. Since emergency braking is somewhat risky, does not provides great passengers experience and there is risk of passengers injuries if braking occurs at high speed, usage of stop crane without strong reason is prohibited and may lead to fines. In some cases law enforcing authorities may even arrest person for incorrect usage of stop crane, depending on circumstances and consequences.

Russian Underground (subway)

In subways derailment usually less dangerous than anywhere else (speeds are lower, train can't jack-knife in tunnel, etc). It is very dangerous to stop in tunnel if fire appears. And emergency braking in the middle of tunnel could be bad idea because third rail energized with 825 volts DC current quite dangerous to passengers. It is better to try to reach station, even in emergency. So, there is no emergency brakes directly visible to passengers. However really, Russian subway wagons still have hidden stop cranes and there is even simplified train controls allowing each wagon to act on it's own if really needed. It is worth to mention that there is door control handles visible to passengers instead. These handles intended to unlock pneumatic train doors in the case of emergency by removing air pressure from doors so they could be opened manually if needed. Subway trains have special logic and alarms preventing train from starting movement if doors were not closed and alarming driver or engaging brakes if doors became open during train movement. Penalties for misuse of emergency handles opening doors resemble penalties for stop crane misuse in usual trains.

Images

References

Hall, Stanley (1989). Danger on the Line. Ian Allan.

See also

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