Ngauranga Gorge
Motorway Management System
View down Ngauranga Gorge
Gantry supporting signs
(click to enlarge)
Variable speed signs (click to enlarge)
Gantry supporting variable speed signs (click to enlarge).
The incident detection equipment, the electronic signs and the optical fibre communications that link the system elements are all state-of-the-art. The major innovation embodied in the Ngauranga ATMS is the software used to integrate the elements of the system, allowing the operator to concentrate on traffic management rather than on system operations.
The motorway management system was designed as an integrated control system. It does not incorporate any “sub-systems" that require operator attention, and information about any aspect of the system is no more than a mouse-click away.
The software controls all equipment items and data sources. It “knows" the current status of equipment, the displayed messages and speed limits, traffic levels, weather conditions, lane closures and a host of other factors. The system can therefore make “intelligent" decisions on matters that do not need direct operator involvement. It also allows information to be presented to the operator in a manner that is customised to the current task.
Examples include:
- An overview map showing the traffic levels and current sign displays, coupled with a CCTV control panel and an event log.
- Incident processing and a response plan preview, aided by a detailed local map and image of the affected site.
- Panels to access stored data.
- Full-screen or miniature current weather displays.
Once an incident has been detected the operator will implement a pre-programmed response plan. Response plans include driver information messages (on variable message signs) warning motorists of hazards and reduced speed limits on variable mandatory speed signs (VMSS). Response plans are an important component of the system.
The software treats any significant change in the overall Ngauranga ATMS status as an “event". Events arise from:
- External system resources. For example, a stationary vehicle detected by a video image processor.
- Internal determination from acquired data. For example a wind speed threshold is exceeded or communication with a device is lost.
- Scheduled functions such as regular reports.
- The operator, who detect incidents or change the signage.
These, with many lower level events, are recorded in an Event Log, including the source and a timestamp. This provides a complete audit trail.
Some events require a response. These may be traffic related incidents, faults requiring maintenance or reminders of tasks to be done.
All situations/incidents are brought to the attention of the operator. Once acknowledged a process is launched which allows the operator to
Verify ––> Classify ––> Respond ––>Close
Verification is typically by use of CCTV cameras, although other means may be appropriate. To help the operator, the nearest detection camera is automatically patched to a designated “incident monitor".
Classification involves the addition of information, indicating for example the severity of a crash, the number of lanes affected.
As soon as the operator has verified and classified the incident, a Response Plan is launched. There are pre-programmed Response Plans for a range of situations. The appropriate plan is selected by the system, based on automatic and manually entered information. Plans provide instructions and guidance to the operator.
Two special weather monitoring stations are linked to the system and collect data on rainfall, road surface moisture, wind and visibility. When the climatic conditions are likely to affect driving conditions, the system will initiate response plans which lower speeds and display warning messages.
