New Zealand Signalling Overview

The safe operation of a railway depends both on the signalling (i.e. the hardware) and the safeworking rules (the software) that define how the hardware is used.

Two systems are used in New Zealand - Automatic signalling (with several variations) and procedural (in non-track circuited territory - points indicators/signals at crossing locations only).

This page decribes the relationship between signalling and operating rules in New Zealand in 2013.

Some of the Rules and Regulations can be read on my Safeworking page.

Extract from an explanation of Automatic Signalling in the 1988 Rule Book.




Automatic Signalling


Single Line Automatic (SLAS)

Timetable authority and a clear Departure signal are required to enter a single line section. The points are hand operated. The 1965 Regulations for Automatic Signalling are quite complicated - they were written before the use of radio communication.

Running signals are Three-Position and have a top unit and a marker for the lower unit (i.e. the lower unit is fixed red). Signals operate automatically.

To depart from the Loop the Releasing Switch is used to clear the Departure signal. The intermediate signal shows yellow if an opposing train in the next section (double yellow). An illuminated L-light on the Arrival signal indicates that the points are set for the loop.

Centralised Traffic Control (CTC)

A clear Departure signal is sufficient authority to enter a single-line section. The signals and power points are operated remotely by computer in Train Control in Wellington. The last traditional CTC panel (at Upper Hutt) was decommissioned in 2007.

All running signals are Three-Position and have either two units or a top unit and a Marker. Multi-unit signals provide more aspects than the three available with a single three-position unit.

In the 1988 Rule Book there is a separate set of CTC Regulations; in the 1965 book there is a single set of Automatic Signalling Regulations.

Double Line Automatic (DLAS)

All movements are controlled by fixed signals under the Automatic Signalling Regulations. Signals may be automatic or controlled - operated by a signalman or remotely from Train Control. Some stations can be switched out, converting the mainline running signals to automatic operation. Points are usually power operated - exceptions are switchlocked sidings and switchstands.

All running signals are Three-Position and have either two units or a top unit and a Marker. Multi-unit signals provide more aspects than the three available with a single three-position unit. An illuminated A-Light amends the rules applicable to the signal.

In the 1988 Rule Book there is a separate set of Double Line Automatic Signalling (DLAS) Regulatons; in the 1965 book there is a single set of Automatic Signalling Regulations.

Automatic Signal Rules (ASR)

Introduced in 2012 to allow the introduction of bi-directional working, these rules are used in some areas previously worked by the Double Line Automatic Signalling and Centralised Traffic Control Regulations.

The Automatic Signalling Rules introduce new concepts and terminology.



The diagram is too large to go here. Click here to view it.




Non-Track Circuited Territory


Track Warrant Control (TWC)

A track warrant issued by Train Control is required for all movements in TWC territory, whether on the single line or at a crossing loop. There are three types of loop - manual, points indicator and arrival signals. Initially most stations were equipped with points indicators but there has been a programme to install Arrival signals.

Points at indicator and arrival signal loops are power operated. Both the Loop and Main are track circuited but there is no track circuiting between crossing stations. (Right Indicator Loop).

Operating procedures are defined in the Generic Track Warrant Regulations.

Two Position

The remaining pocket of two-position working is at Masterton. Read about the differences between two and three position signalling.

Masterton is a pocket of two-position working in Track Warrant Territory.

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Last Updated: Sat 9th November 2013

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