Priority of emergency vehicles
V2X and emergency vehicle priority
Emergency vehicles are driving fast and are allowed to break the traffic rules. The most difficult situation they experience is at intersections. There, they can be delayed a lot by the heavy traffic. Additionally, the chance of an accident is high, especially if they must enter on red light.
This is where emergency vehicle priority can help, even in saving lives. Every second counts! If the vehicle is guaranteed to pass on green with an almost empty intersection, it will get to its intervention faster and much safer.
All that should be done is to equip the vehicle and the traffic light controller with a V2X capable unit. Thanks to its decentralized nature, V2X allows a secured and safe way of getting priority.
How does it work
The On-Board units (OBUs) in emergency vehicles send out several times per second messages. The so called CAM message contains the state of the vehicle – its position, heading and speed and the lightbar (blue light) status. The RSU checks if the vehicle is going to its intersection and if the blue light is on. If it does, the traffic light controller assigns green to the approach from which the vehicle comes. All other directions have red. Hence, the emergency vehicle passes quickly with no cross traffic. Immediately after passing the intersection the controller returns to its normal operation.
Intersection selection
In the city centers, the intersection are very close to each other. In this case, the traffic controller has to activate the priority already at the moment when the vehicle is still at the previous intersection. If the vehicle turns at the previous intersection and does not continue to this one, the priority was active for nothing.
The solution to this problem to request priority at intersections, through which the vehicle will go. The vehicle can use its own digital maps along with knowledge of the place of intervention to select the intersection it will pass through.
It is not only priority...
As with the public transport, priority is only one (yet the most relevant today) benefit of having OBU on board of the emergency vehicle. As soon as the lightbar is activated, the vehicle starts to send a warning message for drivers of the cars in surroundings. This message, when displayed on a dashboard, helps driver to take appropriate actions and make space for a safe passing of the emergency vehicle.
The figure above shows a warning displayed to a bus driver, telling him to stay at stop during the passing of the emergency vehicles.
Our solution
Our solution for emergency vehicle priority offers to following:
- We offer units with long range and high reliability
- The units have in continuous operation for several years – no pilot tests but everyday service
- We have experience from many types and roles of vehicles – from fire brigade to ambulances, from passenger cars to cisterns.