BlipTrack Bluetooth sensors reveal traffic anomalies in Danish city


Denmark’s second-largest city, Aarhus, has been using BlipTrack Bluetooth sensors for several years to collect vehicle movement information and can now see the effects of construction projects, roadworks, accidents, and faulty traffic lights, on road traffic.

Blip Systems’ Bluetooth-based monitoring devices have been placed on the city’s entire road network, including adjacent highways, providing the authorities with both real-time and historic traffic information, including driving times, speed, dwell times and flow. Besides the benefits of real-time reporting, which enables the city to gain in-depth insight and understanding of current road density, flow and formation of queues, and share traffic information with road users on message signs, the historical data is now being used to detect driving time anomalies. This means that the city can pinpoint road sections and intersections where driving times deviate from the norm, as a result of various unexpected factors.

The data provides a thorough comparison of current vs typical driving times, minute-by-minute throughout the day. The typical drive-times, which are continuously updated, are based on various type of days (weekdays, weekend, holidays, etc.) and time of day. If they deviate from typical parameters, the system automatically ‘flags’ them. As the system logs and visualizes all deviations, traffic engineers can create historical performance and reliability reports based on deviations from the norm. The city is provided with an overview of the current situation and tendencies over time, to initiate countermeasures. Alarm visualization can be displayed in various ways, such as over time and for each road section, based on intersection errors, or the impact of a major traffic accident, and can also show the scattering effect that can cause both a deterioration and improvement of drive-times.

Aarhus has around 230 intersections regulated by traffic lights, and if just one is not working optimally or breaks down, it directly affects vehicle flow in a large surrounding area. While the signal installations have built-in alarm systems that warn about mechanical errors, such as defective bulbs, programming errors and communication problems, they are unable to report on the resulting consequences. This means a sudden increase could result in major gridlock, without warning. Since the Bluetooth sensors measure both short and long distances, as well as turn flow through intersections, and groups of lights, issues are now detected, enabling the city to ensure they are working correctly and programmed optimally.

“The benefits we have gained from the solution since implementation are very significant,” noted Asbjørn Halskov-Sørensen, ITS project manager for Aarhus Municipality. “We now discover errors and irregularities that we would not have a chance to see otherwise. In addition, it is extremely easy to study how incidents of various kinds influence the road network. 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. Ultimately, the data contributes to an improved economy and a better environment, through reduced driving times and fuel consumption, and thus reductions in greenhouse gas emissions from vehicles.”

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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).