Stockholm trials ambulances that jam other drivers’ speakers

Thomas McMullan Read more January 18, 2017

Swedish authorities are to trial a new system for ambulances that has the power to hijack in-car sound systems, and play messages warning drivers that they need to get out of the way.

Stockholm trials ambulances that jam other drivers’ speakers

Students at the KTH Royal Institute of Technology in Stockholm have come up with a way for emergency vehicles to jam other drivers’ audio systems. It does this by hijacking the Radio Data System (RDS) protocol in FM radio broadcasts, which embeds digital information such as song titles and station names. The ambulance uses this to stop music from playing, and relay a message via the speakers: “Emergency vehicle approaching, please give way”.

In order for it to work, drivers will need to have their radio turned on, but the system can also interrupt CDs and music playing over Bluetooth. The cars will also need to have RDS capabilities, but it is thought that this will cover two-thirds of cars on Stockholm’s roads.

“Often drivers have only a few seconds to react and give way to emergency vehicles,” said Mikael Erneberg, an engineering student from KTH who co-created the system. “The optimal warning time is at least ten to 15 seconds.”

The technology calculates how wide its signal area should be based on a number of factors, including traffic density and vehicle speed. This should, in theory, stop drivers having their music interrupted by ambulances barrelling down a hard shoulder on the motorway.

With loud music cocooned behind insulated glass, it can often be difficult to hear an ambulance approaching until it’s only moments away. Erneberg and his partners’ solution is clever in how it targets this problem from within, but it needs to contend with situations where interruptions may be unwarranted. What if you’re in a parallel road, for example – away from the path of the ambulance but still within the signal’s target area?

A limited number of ambulances and fire engines will trial the system over the next few months. If it turns out to be successful, Sweden will consider rolling out the technology across the country.