New radar sensors increases road safety

Saab has developed two new road radar sensors that have multiple uses – in speed cameras, to compile traffic data, measure traffic flows and provide variable speed signs with information – all with the goal of improving road safety.

These functions already exist today, but on too few roads. Radar sensors, which are generally seen as more cost effective and flexible than current technology, provide enhanced traffic functions, plus the ability to control traffic cameras and speed limit signs for increased compliance with speed limits and increased availability.

“Our vision is that speed limits and certain traffic regulations can be adapted to the prevailing circumstances that exist on any given occasion. We are confident that, with the right technology, we can increase safety and improve the flow of traffic, and what is more, do this cost effectively,” says Mikael Seyfarth, business developer within civil security at Saab.

Speed limits that vary depending on road conditions, visibility and traffic flows already exist. Selected road sections in, for example, the UK, USA, New Zealand, Netherlands and Sweden, have been equipped with digital signs that indicate the maximum permitted speed for the conditions prevailing at that particular moment. Studies show that variable speed signs lead to increased respect for the speed limit, with substantially reduced accident rates as a result.
Much of the technology in use today is outdated

“The successful experiments that were carried out in Sweden suggest that the use of variable speed signs should increase, but much of the technology being used today is outdated,” says Mikael Seyfarth.

Today, variable speeds controlled by the flow of traffic are regulated by sensors that are buried in the ground, a procedure requiring extensive construction work that disrupts the flow of traffic. Radar sensors mounted on roadside poles is not just a faster, simpler and less costly option to install, it also allows a number of additional functions for traffic statistics, earlier detection of vehicles and the ability to constantly monitor vehicles at an intersection. Altogether, this leads to better regulation of variable speed signs. The radar sensors are positioned to support the desired regulation function, regardless of what the roads look like. Altogether this leads to increased safety.
The sensors complement each other

Saab’s newly-developed radar sensors, SIRS-100 and SIRS-200, detect and register vehicles in all weathers, day or night, regardless of lighting conditions. By combining the two sensors, the range is between 2-120 metres. It allows for multiple uses, such as measuring speed and predicting the traffic flow from a distance and, for example, closely observing a vehicle approaching an intersection. The radar sensor that detects the approaching vehicle sends the information to the variable speed sign on the main road, which automatically reduces the speed limit to facilitate joining.

Furthermore, by equipping the main road with a speed camera, the system ensures that the traffic safety camera is adjusted to correspond to the variable speed limit in force. Connecting speed surveillance to the variable speed signs increases the likelihood that the speed limits will be observed, while road administrators can monitor the extent to which the limits are followed. The radar sensors have advanced statistical tools that record vehicle types, the number of vehicles, their speed, plus the date and time.

“Our view is that a combination of variable speed limits and traffic cameras based on radar technology provides a better solution for variable speed, and a noticeable increase in speed limit compliance and thereby road safety,” says Mikael Seyfarth.
About SIRS-100

* Can be used to provide variable speed signs with the correct information, to collect traffic statistics and to measure traffic flows.
* Detects vehicles from between 0.5-50 metres
* Indicates the distance, speed, time, date, vehicle type and heading.
* Measures speed with a margin of error that is less than 2 km/h
* Detection zone of ±50º
* Has a high update speed (50 times per second)
* Is about the size of a cigarette packet (120x70x28 mm)

About SIRS-200

* Can be used in speed cameras and variable speed signs
* Detects vehicles from between 2-120 metres
* Indicates the distance, speed, time, date and vehicle type.
* Measures speed with a margin of error that is less than 1 km/h
Has a high update speed (25 times per second)
* About the size of a DVD case (145x180x35 mm)
* Both sensors detect vehicles at speeds up to 260 km/h and work in temperatures ranging from -40 to +65 degrees.

The sensors are mounted on poles along the road and therefore do not need to be installed in the roadway. This makes the introduction of the sensors considerably more cost effective and increases their availability.