the train protection & warning system (tpws) is a train protection system throughout the two uk passenger main-line railway networks, and in victoria, australia.network rail: step change in safety delivered on time and under budget - monday 29 december 2003 it automatically activates brakes on a train that has passed a signal at danger or is overspeeding. it is fitted at selected sites, including some lines where automatic train protection (atp) is installed. unlike atp, it does not aim to stop trains at or before a signal that is at danger - it aims to stop the train before the point at which a collision with another train could occur, excluding rear-end collision with a train in front. according to the health and safety executive, it is estimated to prevent between 65% and 80% of fatalities that would be stopped by a full atp system.  a standard installation consists of an on-track transmitter adjacent to a signal, activated when the signal is at danger. a train that passes the signal will have its emergency brakes activated. if the train is travelling at speed, this may be too late to stop it before the point of collision, therefore a second transmitter may be placed on the approach to the signal that applies the brakes on trains going too quickly to stop at the signal, positioned to stop trains approaching at up to 75&nbsp;mph (120&nbsp;km/h). at around 400 high-risk locations, tpws+ is installed with a third transmitter is used further in rear of the signal and this increases the effectiveness to 100&nbsp;mph (160&nbsp;km/h). when installed in conjunction with signal controls such as 'double blocking' (i.e. two red signal aspects in succession), tpws can be fully effective at any realistic speed. tpws is not the same as timed train stops that accomplish a similar task with different technology. ==history== tpws was developed by british rail, later railtrack, working group as a development of the automatic warning system, after a 1994 decision that the nationwide installation of a full automatic train protection system was not practicable. trial installations of track side and train mounted equipment were made in 1997, with trials and development continuing over the next two years.  the rollout of tpws accelerated when the rai
Train_protection_systems