A system which sets routes ahead of the train using information from a train describer and the timetable without the need for intervention by the signaller.

An automatic signal is a signal that is controlled through track occupancy alone and not by a signaller. Typically each section of track has a track circuit and an entrance signal. As a train enters each section of track, its signal displays danger (stop) and changes other signals in the sections behind the occupied track to caution and then proceed progressively.

See also controlled signal.

A subsystem of some modern control systems that monitors trains' service by means of train describers, track circuit occupations or by balise-based data collection.  ATM is normally a subsystem of automatic train supervision (ATS) and is may also referred to as train service monitoring.

ATO is a safety enhancement where the rail vehicle automatically performs key operational functions.

Typically, ATO is Semi-Automatic Train Operation (STO) where the train stops automatically when/where required, but the driver is responsible to start the train, operate doors and respond to emergencies.

Driverless Train Operation (DTO) occurs where starting and stopping are all automated and an attendant only operates doors (and drives the train in emergencies).

Unattended Train Operation (UTO) is where all operations such as starting, stopping, door operation and emergency handling are fully automated.

ATO systems are typically used in rail environments such as subways and elevated railways which safety-wise are free of humans around the track. However Rio Tinto is using DTO in mainline operations in outback Western Australia (also relatively free of humans). 

ATP is a system that prevents a train from exceeding its authority e.g. passing a signal at stop (SPAD) or exceeding a speed limit.

Systems typically advise the driver (visually and audibly) of the impending or actual breach. Should the driver fail to bring the train under control, then the train's brakes are automatically applied (penalty brake application), bringing the train to a stand.

There are two types of ATP:

Continuous, where the train borne equipment is constantly updated from a conductor (cable or rail) laid along the block, relaying vital information to the train.

Intermittent, where the train receives vital information via transponders (balises) placed at strategic locations and GSM-R radios.

Electronic system for reporting train movements based on the transfer of train identification numbers to a train describer in a display panel or VDU.

ATS is a subsystem of some modern train control systems which monitors running trains and provides data so that their service may be adjusted by controllers to minimise delays.

ATS may also include automatic train regulation (ATR) via automatic routing system (ARS). ATS requires automatic train monitoring (ATM) to be able to automatically adjust the timings of trains.

ATS supports automatic train control (ATC) by managing the routes or network