The higher performing EP brake uses a "main reservoir pipe" feeding air to all the brake reservoirs on the train, with the brake valves controlled electrically with a three-wire control circuit. This provides between four and seven braking levels, depending on the class of train. It also allows for faster brake application, as the electrical control signal is propagated effectively instantly to all vehicles in the train, whereas the change in air pressure which activates the brakes in a conventional system can take several seconds or tens of seconds to propagate fully to the rear of the train. This system is not however used on freight trains due to cost. Electronically controlled pneumatic brakes Electronically controlled pneumatic brakes (ECP) are a development of the late 20th Century to deal with very long and heavy freight trains, and are a development of the EP brake with even higher level of control. In addition, information about the operation of the brakes on each wagon is returned to the driver's control panel. With ECP, a power and control line is installed from wagon to wagon from the front of the train to the rear. Electrical control signals are propagated effectively instantaneously, as opposed to changes in air pressure which propagate at a rather slow speed limited in practice by the resistance to air flow of the pipework, so that the brakes on all wagons can be applied simultaneously, or even from rear to front rather than from front to rear. This prevents wagons at the rear "shoving" wagons at the front, and results in reduced stopping distance and less equipment wear. There are two brands of ECP brakes available in North America, one by New York Air Brake and the other by Wabtec. These two types are interchangeable. Reversibility Brake connections between wagons may be simplified if wagons always point the same way. An exception would be made for locomotives which are often turned on turntables or triangles. On the new Fortescue railway opened in 2008, wagons are operated in sets, although their direction changes at the balloon loop at the port. The ECP connections are on one side only and are unidirectional. Accidents with brakes Defective or improperly-applied brakes may lead to a runaway train; in some instances this has caused train wrecks: Lac-Mégantic derailment, Quebec (2013), handbrakes were improperly set on unattended parked crude oil train, runaway tank cars rolled down