3. Purpose

The purpose of this protocol is to create a standardized way to communicate between systems at the local level and systems at the regional level regardless of supplier and technology. The goal is to be able to easily add and remove signals in new facilities and applications without having to expand or change the standards and guidelines. This means that the protocol, as opposed to many other standards and protocols do not include detailed information about the signal exchange but is focused on defining the types of signals which are then described construction or items specifically. The goal is that in the long term, based on installed systems and objects, is to be able to produce signal exchange lists of type object that can be reused in new contracts so that alarm messages, commands, etc. have the same names regardless of facility or provider.

The purpose of the signal exchange is to provide information relating to, for example, traffic control managers and administrators. E.g. the information needed to monitor and control the road side equipment, as well as the information that can be used for statistics and analysis of traffic and equipment’s status. For instance, alarms contains sufficient information to be able to create a work order in Maximo which is then sent to the operating contractor, ie. sufficient information about the type of skills and equipment necessary to correct the error. Additional detailed information about an alarm (e.g. which I/O card has broken, the LED chain that is out of order, etc.) can be read on site via vendor-specific web interface or operator panel.

3.1. Identified requirements

In order to provide an information exchange that is not dependent of technology area or vendor specific information - four message types have been identified that cover all types of information that the Swedish Transport Administration needs. The information in each message is dynamic and is defined by technical area or specific equipment using a specific signal exchange list (SXL). The SXL also represents the interface between the supervision system / other facilities and equipment. The four message types are:

  • Alarm. System, traffic- or monitoring alarms that require action by the traffic operator or traffic engineer. Usually sent from the equipment to the monitoring system when they occur.

  • Aggregated status. An aggregated status that gives an overview glance of the status of the road side equipment. Usually sent from the equipment as soon as it changes to the monitoring system.

  • Status. Status changes, indications and detailed information should be logged or made visible at the monitoring system. Sent upon request from the supervision system / other facility or using subscription (either at status change or at set time interval).

  • Command. Commands sent from a supervision system or other facility to alter the equipment / object status or control principle.