Electronically controlled pneumatic brakes

Electronically Controlled Pneumatic brakes are a type of modern railway brakes which offer improved performance compared to traditional pneumatic (compressed air) brakes.

Overview

Traditional systems apply the brakes sequentially from car to car along the train, meaning that up to 2 minutes can elapse between operation of the control valve on the leading locomotive and the application of brakes on the last car of a 150 wagon freight train.cite news | title=The year of the electronic air brake | url =http://www.railwaygazette.com/news_view/article/1998/02/1240/the_year_of_the_electronic_air_brake.html| work =Railway Gazette International | date = February 1998 | author = Doug Klink] In contrast, ECP braking uses electronic controls which make it possible to activate air-powered brakes on all the wagons throughout the train at the same time. Applying the brakes uniformly and instantaneously in this way gives better train control, shortens the stopping distances, leads to a lower risk of derailment or of coupling breakage.

Testing

Greater intervals between brake tests are also likely because of the ability of ECP brakes to self-diagnose which should generate large cost savings that will help pay for the system to be installed. [ [http://www.fra.dot.gov/us/press-releases/163 Federal Railroad Administration] ]

The benefits are better control of braking, less equipment wear from pushing and pulling between cars, shorter stopping distance and improved headways. [International Railway Journal April 2000 p23]

Control and Power

When first developed, ECP brakes needed a number of wires along the train to control solenoids on each wagon to release the brakes, and were not considered economic for freight. This has changed with the introduction of electronic controls, allowing data to be transmitted by two-conductor wire or radio from the loco to a microprocessor on each car, where locally powered valves hold the desired pressure in each brake cylinder.

Fortescue

ECP can use axle-generated power or wire distributed power. The Fortescue railway uses wire distributed power at 200V DC. The Fortescue line also places the two brake pipes and single control/power cables on one side of the wagons only, as trains only operate as block loads and the wagons are not normally reversed. [ Railway Gazette International July 2008, p427 ]

Compatibility

ECP brakes may or may not be backwards compatible with older brakes. In the case of the Fortescue railway, the new ECP brakes are incompatible in several ways.

* the wagon to wagon pipes are straight and are on one side of the waggon only, and do not cross over to the other side underneath the coupling.

* wagons are one sided, though locomotives are dual sided for flexibility. Note that the wagons are onesided to suit a rotary tippler. [ http://www.railpage.com.au/f-t11340333-s15.htm ]

Progress and examples

* 1990's- first trials on BN in the 1990's TSM of Kansas City operated more than eight coal-and intermodal trains using their "EABS" ECP for BN, CP and Amtrak. TSM purchased by Wabco, 1998.

* The first ECP-equipped Norfolk Southern train in the United States began operating on October 11, 2007 with the Norfolk Southern Railway. [cite news | title=ECP brakes go live | url =http://www.railwaygazette.com/news_view/article/2007/11/7914/ecp_brakes_go_live.html | work =Railway Gazette International | date = November 2007 | page=673] [Trains January 2008, p22]

* January 24, 2008 - first trials on BNSF [ [http://railwaysafrica.com/index.php?option=com_content&task=view&id=2212&Itemid=0 New ECP brakes for US coal] Railways Africa February 1 2008]

* Testing of ECP braking on Spoornet's Richards Bay heavy haul line in South Africa was also expected to begin by the end of 2007, for service in 2009. [cite news | title=ECP braking to Richards Bay| url =http://www.railwaygazette.com/news_view/article/2007/07/7618/ecp_braking_to_richards_bay.html| work =Railway Gazette International | date = July 2007] [ RailwaysAfrica 5/2007 p22 ]

* ECP braking is also being tested in Australia. [ [http://www.railinnovation.com.au/innovation/technologies/ozecpbrakes.html OZ-ECP Brakes] ]
* May, 2008 - new Fortescue iron ore railway has ECP.

* September, 2008 - Canadian Pacific Railway has begun testing ECP-equipped coal trains on its coal haul route in British Columbia.

See also

* Railway air brake

References