Anthony Hildebrand outlines the benefits of Emergency Vehicle Preemption systems that allow authorised vehicles to pass through traffic intersections swiftly and safely by giving them green lights as required.
Speed is crucial for first responders: getting to the scene of an accident or incident can mean the difference between life and death. But safety is paramount, too. There’s no point in racing to an emergency, only to cause a traffic accident on the way there – or on the way back to a hospital.
For this reason, Emergency Vehicle Preemption (EVP) systems have been developed: to allow authorised vehicles to pass through traffic intersections swiftly and safely by giving them a green light as required. The concept is straightforward, but of course it’s a little more complicated than that in practice – particularly in cities where traffic congestion means that intersection signal timings are carefully calibrated to ensure optimal traffic flow.
A properly configured EVP system provides:
- An improvement in response times of up to 25 per cent;
- A reduction of up to 70 per cent in intersection crashes involving emergency responders;
- A prevention of crash injuries and related costs;
- A reduction in property damage costs;
- Decreased liability for crashes with civilian motorists; and
- A quick, demonstrable recovering of the investment from the above benefits
Global Traffic Technologies (GTT) is a pioneer in this field. Its technology has been used in North America for over 45 years and it holds a portfolio of US and international patents focused on providing safe and reliable traffic solutions. The company recently announced an expansion of its international strategy, bringing its EVP and public transport systems to wider global markets.
GTT’s Opticom EVP systems are designed to enable police cars, fire trucks and ambulances to navigate congested intersections more effectively. As a result, agencies can improve response times while reducing the potential for costly accidents.
In an emergency situation, an approaching vehicle equipped with GPS and a special radio emitter sends a request to the receiver located at the intersection (other systems use Infrared to communicate, but this is limited to line of sight – GPS has longer range and can ‘see around corners’). The vehicle can be hundreds of metres away from the intersection at the point that the request is sent. Upon receipt of the request, the receiver runs the lights through a cycle – green lights for cross-traffic truncate, turning yellow and then red.
This is timed so that the approaching emergency vehicle gets a green light before it arrives, and can pass unhindered on its journey to its destination.
By stopping cross-traffic through the use of a regular traffic light cycle, there is minimal likelihood of panic by other drivers, which can also contribute to accidents.
In the case of authorised vehicles approaching an intersection from different directions at the same time, the system prioritises the vehicles to avoid danger and will notify a driver if they are likely to need to stop.
Opticom EVP equipment also logs data, including the vehicle’s ID, transit time, final green status and other significant event information. It is then available for retrieval and analysis by GTT’s Central Management Software (CMS). The equipment can also interface with other ITS and reporting systems and intersection equipment; and it can suppress vehicle identification and associated records where privacy is required. Updating can be done remotely via the CMS, without needing to physically go to each intersection.
One of the keys to the success of the EVP system is its focus on simplicity whenever possible. GTT’s products require no driver interaction: they are usually activated through integration with the lights or siren systems on the vehicle.
The intersection equipment automatically assembles its communications network without human intervention. Programming of intersection activation approaches is done via a simple graphical laptop interface and may be preconfigured at the central office prior to equipment installation.
Since the system causes the traffic signals to move to the required green signal in a natural manner, driver training focuses on reinforcing the importance of driving to the indicated signals.
A relatively recent deployment of the system took place in Doha, the capital of Qatar. The Qatar Public Works Authority, Ashghal, was looking for a system not only for ambulance services, but also for Civil Defence vehicles, which provide security and crisis response services. The system is proving to be a highly successful implementation that is reducing accidents and increasing response times.
The EVP system has so far been installed at 80 critical junctions across Doha, in two phases. In the first phase, which began in April 2014, 25 intersections and five roundabouts were included, while 15 ambulances and 10 vehicles from Qatar’s Civil Defence were fitted with transmitters.
In the second phase of the EVP system rollout, a further 50 intersections across Doha city and surrounding neighbourhoods were included. There are plans to expand the system even further in the future.
User surveys
The system is integrated into Doha’s SCATS Urban Traffic Control System and is monitored from Ashghal’s Traffic Control Center in West Bay. The CMS enables those in charge of the system to manage devices and units and ensure the efficiency of their performance. It also allows the system to be monitored and for reports to be generated for each intersection, as well as indicating when maintenance is required.
Ashghal conducted surveys of users on the effectiveness of the system and the results were comprehensive: all of the ambulance and Civil Defence drivers agreed that the system: “Contributes significantly to reduce the likelihood of emergency vehicle traffic accidents,” and that it: “Contributes to reduce the time it takes to respond to emergency situations.”
GTT has also recently converted a system on Las Vegas Boulevard from IR technology to GPS. This conversion was for very practical and local reasons: IR was limited to line of sight and Las Vegas’s palm trees (as well as less iconic details, like pedestrian overpasses) were obscuring the direct connection between vehicles and intersections. GPS, as established, doesn’t require this line of sight connection.
Eleven intersections on Las Vegas Boulevard were converted from IR to GPS. Early data seems to point to a 32 per cent reduction in the time it takes to get through the intersections – significant time savings in an area as busy and congested as the Las Vegas Strip.
As a result of this success, authorities in the region are looking at expanding the scheme to cover additional intersections in other local ‘hotspot’ areas.
As well as its EVP systems, GTT provides Transit Signal Priority systems, which enable public transport agencies to extend or truncate green cycle times at traffic signals for more accurate schedule adherence.
In turn, public transport vehicles – including buses, light rail trains, street cars, cable cars and trams – are on the road less, which reduces fuel and fleet costs for more profitable operations, as well as reducing pollution in the form of carbon emissions. The system allows the users of both EVP and TSP systems to leverage and use the same intersection equipment, monitored and controlled using CMS.
This integration can prove particularly effective in the case of large events, which are often served by park-and-ride vehicles that transport many attendees efficiently. If these public transport vehicles are equipped with priority control devices, CMS can turn red lights green when they approach. However, if a high priority vehicle requires the other approach, it will override the in-progress priority control and give it to the emergency responder.
This capability is also useful for disaster evacuation. Event and disaster evacuation plans may be set up in advance, ready to implement at the touch of a button. Alternatively, they may be scheduled for implementation at specified times and dates, yet may be cancelled if required.
The third branch of GTT’s work involves its Canoga Traffic-Sensing solution, which captures precise, real-time traffic data – including for bicycles – so traffic engineers can make faster, more accurate decisions to keep traffic moving smoothly on roadways.
Article published in Crisis Response Journal on January 4th, 2016.
