Optimising Aarhus's transport system with Bluetooth (Denmark)



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By News Editor / Uuendatud: 31 Aug 2015
Policymakers are continuously trying to increase the performance of transport systems. To do this they need effective monitoring methods in place in order to understand what is going and what the issues need to be solved. That’s why in 2011 city officials in Aarhus decided to test a highly innovative Bluetooth traffic monitoring system to see how it could be used in the development of urban mobility solutions. Today, the city has more than 130 units installed across the city.
Aarhus is a port city located in the centre of Denmark. It is the nation’s second largest city and has over 323 000 people, almost 260 000 of which live in the inner coherent urban area. Greater Aarhus has a population of 1.2 million people. Although most people in Aarhus (52 per cent) use a private motor vehicle for their trips, an almost equally large share of the trips are sustainable: walking (20 per cent), cycling (16 per cent) and public transport (10 per cent).
Initially, Aarhus looked at traditional solutions to monitor its transport systems, like automatic number-plate recognition technology. However, Bluetooth seemed like a more cost-effective solution. Sceptical of the solution at first, Aarhus decided to introduce the technology in steps and to test different systems.

WHAT IS BLUETOOTH?  Bluetooth is wireless technology that exchanges data over short distances using radio transmissions. It was created in 1994 by Swedish company Ericsson as an open standard to allow connectivity and collaboration between disparate products and industries.

In action 
After a tender phase the Bluetooth systems of three different companies were implemented and tested on two ring roads. Aarhus selected a traffic sensor system, BlipTrack, created by BLIP Systems (Bluetooth Local Infotainment Point), and rolled out the selected technology for the major roads. The BlipTrack system consists of three Bluetooth sensors and in order to boost the detection rate it uses two directional antennas. The sensors detect vehicles’ Bluetooth systems and Bluetooth signals coming from devices such as mobile phones and tablets. The distance between nodes has to be at least 500 metres and nodes are placed between intersections where traffic is in motion.
In addition, algorithms were developed to filter the data that was generated. This process reduces the amount of data but produces an overall dataset of better quality. Major roads from Ring Road 1 and out were equipped with Bluetooth data ‘loggers’. To realise this Aarhus co-operated with its two neighbouring municipalities as the loggers need to be located on their roads, and with the Danish Road Directorate for the loggers located on state roads.
The collected data is uploaded using 3G technology and a Local Area Network (LAN) and stored securely on the internet (also known as storing it on ‘the cloud’) where users, such as traffic engineers, can access it using an easy-to-use dashboard. The system allows for simultaneous measurement of multiple lanes, works in all weather conditions, requires no maintenance and can be installed in 15 minutes to existing poles without disruption to traffic.
By combining the data collected by all sensors, an accurate picture about each road user (such as their dwell time, movement patterns, travel times, origin and destination, etc.) emerges. The information of the monitoring system informs and warns city traffic engineers about queues and delays, identifies problem areas, evaluates and calibrates traffic signals, provides information on the capacity of existing roads, and detect changes in traffic patterns.
Challenges, opportunities and transferability 
‘We now have a solution we can use in our daily planning - although we still have a lot to learn,’ admits Aarhus’s project leader, Michael Bloksgaard. A considerable hurdle, he said, was getting familiarised with the technology. ‘When the first pilot started we had a lot of ideas but no experience with the technology. The biggest challenge has been to define what works and especially what does not work.’ This resulted in Bloksgaard drafting a set of steps that identify what to look for when placing Bluetooth loggers.
Bloksgaard describes issues like how to manage the data and achieving the full value of the technology as particular challenges.  ‘We will only have the full use of all the benefits of the solution when we can give information to travellers about travel times, plan our infrastructure investment by congestion and price, and measure the value of infrastructure investments after implementation,’ he said.
At the moment, Aarhus focuses on quick-and-easy access to data at the right level of aggregation in order to ensure that the data will be used. In addition, ensuring good quality of data will also be a challenge. Aarhus will track the quality of the data generated by the system in the form of a check carried out once a year.
Although Aarhus does keep the information it gathers, it supports innovators to develop smart applications, tools and services by making all data public available on their open data site. The municipality also plans activities such as the Aarhus Data Drinks Meetup where developers can meet face-to-face, provides a virtual meeting place were developers can collaborate and also awards financial incentives. Thanks to this approach, different applications (such as one that guides drivers through traffic) have already been developed.
In Depth 
Traffic and demand management
Michael Bloksgaard
Daan Kuiper
04 Apr 2015
31 Aug 2015