Standards Development

Scope

This document defines protocols and message sets between traffic detectors and traffic signal controllers. It is applicable to the various types of traffic detector technologies currently in use for real-time traffic signal controls. The scope of this International Standard is limited to parameter generation to be used for traffic signal control and for the interface between traffic signal controllers and detectors.

This document defines message sets that contain data collection and control protocol for three different types of detectors of traffic signal control systems:

— detectors that deal with occupancy information;

— detectors that deal with image information;

— detectors that deal with vehicle identification.

The scope of this document does not include the following cases:

— interfaces between sensors [including tag or on-board units (OBU)] and detector controllers;

— interfaces between traffic signal controllers and centres;

— when signal controllers only relay data from field-side detectors to central computers;

— when signal controllers receive unencoded electrical signals from cable-connected detectors and not data from detectors.

Physical scope is limited to the communication interface between traffic signal controllers and traffic detectors. The scope does not include the interface between the traffic detector and its own controller.

Figure 1 — Physical scope

This document is limited to the definition of the message sets used to exchange detector information relevant for traffic control and the logical rules governing the exchange of these messages.