ATCS
Automatic Traction Control System (ATCS) is an antiquated design of train traction control system used in some places around the world, developed by Richard & Stein during the 1970s. It was designed to be a very cheap and simple method of train control to combat what was at the time considered to be an economic crisis. Though most systems were phased out during the early 2000s, some still exist today in various forms.
The system provides automatic control of a train network, but all control and power supply equipment is located off the train in a fixed location. This allows construction costs to be significantly reduced, as only motors and brakes must be present on the carriages. Apart from emergency brakes, there is no method of controlling these trains while aboard, and no driver.
Design
Between each set of tracks is a common neutral, as well as a set number of conductors referred to as “channels” that each correspond to a train. A movable “hot shoe” under train cars allows a different channel to be selected for each train on the network, allowing for individual control. Most systems contain 8 channels, but 16 and 32-channel systems have existed in dense areas.
Speed is controlled by varying the voltage; brakes are fail-safe and automatically applied when power is shut off, which is the intended method of braking due to there being no control systems on the train. When the train enters a station, magnets at the platform edge engage reed switches and allow the doors to open when it comes to a stop.
Most systems ran at 670V DC, converted from grid AC power using mercury arc rectifiers. The control system is made up of separate panels, each dedicated to controlling one train. All panels are connected to what is called a “central semaphore” which ensures trains do not enter each others’ block segments.