Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!

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Warning Systems

A number of major research projects and programmes such as COMPASS4D are actively investigating Vehicle to Infrastructure (V2I) solutions for warning applications. The COMPASS4D project ( brings together six European cities to deploy three services based on cooperative systems to warn drivers about an incident on the route ahead.

These systems are significantly more complex to implement compared to vehicle-based approaches, as they require deployment of standardised technology on both vehicles and the roadside infrastructure. They show great potential for reducing certain types of road incidents.

Obstacle Detection

Obstacle detection systems help make the driver aware of objects or people that may otherwise not be noticed. One example is a camera to help drivers with reversing a vehicle – making them aware of obstacles behind them. This type of technology is particularly valuable in avoiding low-speed accidents involving small children who may not be easily visible as a driver reverses down a driveway. The USA is actively considering mandating the installation of this technology in all new cars and light commercial vehicles.

Collision Warning and Crash Avoidance

A variety of technologies such as radar, lasers, and cameras are used in vehicles to detect potential collisions. Crash avoidance systems monitor for safety threats and intervene as necessary, generally on a time scale of under 3 seconds or so. Deployments vary, but most systems provide a visual warning to the driver. They may also pre-tension seatbelts and adjust vehicle braking behaviour to help the driver stop more quickly and safely. These systems have been commercially available in some markets since 2003.

Rollover Warning

Rollover accidents can cause significant loss of life, traffic delay and other expense. Commercial and passenger vehicles with high centres of gravity are particularly susceptible to this type of incident on exit ramps and tight curves. Rollover warning systems calculate the rollover risk based on vehicle data and other sensor input to help drivers adjust their driving before an accident becomes unavoidable.

Lane Departure Warning

LDW systems use video, laser and infrared to help ensure that drivers stay safely in their lanes. If unintended lane departure is detected, LDW systems typically alert the driver with an audible alarm or physical sensation (a haptic warning) such as resistance or vibration. In some cases, LDW systems may also adjust steering behaviour to help the driver safely return the vehicle to its lane. These systems are commercially available from a variety of manufacturers.

Signal phase and timing (SPaT) Warnings

SPaT warning systems are currently being developed in research projects and programmes around the world – including:
  • the European, eCoMove project’s work on traffic light coordination for ecoTraffic Management and Control (
  • V21 in the USA
  • SPaT warnings are intended to inform drivers approaching a signalised intersection about the current signal status and time-to-change. In all cases traffic signals are equipped to capture this information which is transmitted to vehicles – either:
    • directly – via dedicated short range communications
    • indirectly via standard mobile communications to a central traffic operations center which loads the SPaT data to the web. The advantage of sharing SPaT data via the web is that it gives drivers the ability to look several intersections ahead

There are a variety of functions that this kind of information can enable – such as intersection safety, traffic management and public transport management. Specific applications include signal violation warnings, in-vehicle signal status display, vulnerable road user warnings (for example – pedestrians and cyclists), eco-driving support, and commercial and emergency vehicle support.


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