Communications-based train control is a signaling system that utlises telecommunications between the train's on-board computer and wayside equipment to determine traffic management and control of infrastructure. The CBTC system determines the exact position of the train more accurately (moving block) than with the traditional (fixed block) signalling systems.

The increased train location accuracy enables reduced headways while maintaining safety. Thus CBTC results in higher efficiency and safety whilst improving the management of rail traffic.

The features of a full CBTC systems, as defined in the IEEE 1474-2 standard, are:

• Continuous, automatic train control
• High-resolution train location determination, independent of track circuits
• Continuous, high-capacity, bi-directional train to wayside data communications
• Trainborne and wayside processors capable of implementing Automatic Train Protection (ATP) functions
• Optionally, Automatic Train Operation (ATO) and Automatic Train Supervision (ATS) functions.

An industry-determined specification of performance which sets out the knowledge, skills and attitudes required to operate effectively in employment. Competency standards are made up of units of competency, which are themselves made up of elements of competency, together with performance criteria, a range of variables, and an evidence guide. Competency standards are an endorsed component of a Training Package.

A consist is two or more cars in a train. i.e.a train may be a three car consist.

Signal boxes and train control rooms originally used local control panels with buttons or switches to operate the signals and points. The switches and buttons were often positioned directly onto the track diagram on the panel. The buttons or switches controlled a relay or computer based interlocking.

Modern train controllers now use VDU displays in control rooms to control the Computer Based Interlockings via keyboard and mouse manipulations. 

A document, designed by signal design engineers, that defines the signalling controls for each signalling function an interlocking. Generally used to describe electrical and electronic interlockings.

See also Locking Table as applied to mechanical interlockings.

As opposed to automatic signals that operate off devices like track circuits, controlled signals operate directly off the interlocking or by the direct actions of the signaller.

Grade crossings may be protected in two ways:

Passive protection, where only warning signs are deployed to alert of a level crossing, or

Active protection, where warning lights, audible signals, half-boom barriers or gates may be deployed to alert of a coming train.

Where no devices are used, the crossing is unprotected.