Road users in Danish city benefit from Bluetooth traffic monitoring system


Five years after its original deployment, a Bluetooth monitoring system in Denmark’s second largest city, Aarhus, is continuing to provide road users with shorter, more stable travel times, as well as powering digital signs that help them make more informed decisions.

In 2011 Danish company Blip Systems installed 40 of its BlipTrack Bluetooth monitoring units in Aarhus. The network currently uses over 200 sensors, which are set up in and around the city, detecting when a hands-free phone, cell phone or other open Bluetooth-enabled device drives past. This allows the city authorities to calculate travel times, congestion and traffic flows, and pass this real-time information to drivers via variable message signs (VMS).

The municipality can demonstrate significant travel time savings as a result of a host of new initiatives and optimizations, that have been planned using data from the small, Bluetooth-detecting sensors. The city cites the results from several traffic management projects that were based on BlipTrack data:

After the expansion of two new turning lanes and optimization of the traffic lights at a major intersection, a travel time saving of 81 hours a day has been measured, calculated solely on motorists traveling through the intersection during morning and evening rush hour periods, with the total saving for the entire day being undoubtedly higher; At another heavily trafficked intersection, the sensors have measured an average time saving, heading out of town, of as much as 31% from 3:00-5:00pm. Travel time has also become far more stable. Whereas on some days it used to take motorists around six minutes, travel time is now more constant at around two to 2.5 minutes, regardless of the time of day, giving commuters far greater predictability; With the introduction of a new left turn filter onto the ring road, sensors have been able to detect a reduction in travel time of more than 50%.

“Being able to give concrete figures, both to our politicians and to our road users, provides the basis for a far more objective and balanced debate on the things we do on the roads,” explained Asbjørn Halskov-Sørensen, project manager at Aarhus’s Center for Byens Anvendelse. “It is important for us to be able to document the facts when residents and the business community address themselves to us, or further up the system, because they are experiencing long travel times and queues on various stretches. These experiences are often subjective, and travel times tend to feel longer than they actually are.”

Halskov-Sørensen continued, “BlipTrack data is generally used for much more than just being able to measure the effect of signal optimization and roadwork/construction projects, but this is clearly an important part of its application, and something from which we have benefited greatly. Ultimately, the data contributes to an improved economy and a better environment through reduced travel times and fuel consumption, and thus reductions in greenhouse gas emissions from vehicles.”

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About Author


Tom has edited Traffic Technology International (TTi) magazine and its Traffic Technology Today website since May 2014. During his time at the title, he has interviewed some of the top transportation chiefs at public agencies around the world as well as CEOs of leading multinationals and ground-breaking start-ups. Tom's earlier career saw him working on some the UK's leading consumer magazine titles. He has a law degree from the London School of Economics (LSE).