Congestion is a social burden in urban environments...
Urbanisation has been a clear trend in the past decades and is expected to continue, with the proportion of the European population residing in urban areas increasing from 72% in 2007 to 84% in 2050. This urban sprawl is the main challenge for urban transport, as it brings about a greater need for individual transport modes, thereby generating an ever increasing level of congestion. This is recognized as one of the main problems in urban environments by the Green Paper on Urban Mobility. Currently, congestion costs are estimated at €50 billion per year at EU level and this figure could rise rapidly if no action is taken to ease the pressure on the road network.
...and an environmental plague.
Besides the economical aspect, high traffic density has negative effects on the environment. The main environmental issues in towns and cities stem from the dominance of oil as a transport fuel, which generates CO2, and air pollutant emissions such as particulate matter. Air and noise pollution are increasingly worrying. Urban mobility accounts for 40% of all CO2 emissions of road transport, and up to 70% of other pollutants from road transport. According to data from the European Environment Agency, transport accounted for close to a quarter (23.8 %) of total greenhouse gas (GHG) emissions and slightly more than a quarter (27.9 %) of total CO2 emissions in the EU-27 in 2006.
State of the art traffic management systems integrate sensors for traffic monitoring that are complex
to deploy and maintain...
To cope with these challenges, traffic control and traffic management methods and strategies should be tightly integrated. Traffic surveillance generally relies on an infrastructure based on inductive loops or fixed cameras. Although reliable, these sensors are complex and expensive to deploy, and they fail in providing advanced traffic status indicators, such as queue length or delay times, both required by modern advanced traffic light control systems.
...as well as expensive traffic light control systems that are either centralised...
Centralised traffic light control systems rely on a control centre that is collecting information from road sensors scattered throughout the city, trying to achieve a comprehensive knowledge about the controlled area. This knowledge concurs to the evaluation of a traffic plan, i.e. to the assignment of phases and timings to traffic lights; in case of need, traffic experts may override control system decisions. These solutions, though widely used in many large urban environments, are highly expensive requiring extensive communication, a large control centre with large data elaboration power and trained personnel.
Distributed traffic light control systems instead, while still relying on expensive-to-install sensor information, do not need a control centre. Instead, they require explicit information exchange between neighbouring junctions, raising additional infrastructure costs. In addition, configuration costs incurred when installing a control system in a new junction are due to the fact that each control system should know its neighbourhoods.
To lower installation costs, approaches for traffic management based on V2X technology have started
to be investigated...
In the past years, the European Commission has largely promoted R&D on vehicular communication. In fact, the assignment of communication channels for message transmission in 2008 by the European Telecommunications Standards Institute (ETSI) has substantially boosted vehicular communication (V2X). Now the exchange of state information between vehicles (V2V) or between vehicles and infrastructure (V2I and I2V) has reached a good level of maturity which allows its deployment.
...but they assume high penetration rates of equipped vehicles...
The currently investigated applications mainly rely on message exchange between vehicles (V2V), requiring a high penetration rate to achieve the desired goals. These applications range from traffic monitoring, to incident detection to the more complex and futuristic task of traffic management, i.e., substituting traffic lights and road infrastructure via traffic self-regulation of vehicles through communication.
...and seldom consider the road infrastructure,
Infrastructure units (road side units, RSUs) are mainly addressed as additional transmission points for assuring a sent message’s delivery, only. Serving as bridges between cooperating vehicles, they do not play an active role in traffic management. Similarly, no emphasis is posed on the equipped RSU penetration rates and on their best placement to guarantee the largest coverage.
Additionally, most of the developed V2X-applications that aim at increasing traffic flow efficiency work by changing the behaviour of equipped vehicles. On the contrary, adapting the behaviour of the road infrastructure to traffic conditions determined via V2X-based distributed monitoring is only seldom investigated.
losing the whole potential of vehicular communication.
Sending heartbeat messages (Cooperative Awareness Messages, CAMs) about its state, each equipped vehicle generates a great amount of relevant information for traffic management. When being collected, this channel not only enlarges the knowledge about the state of the road, but also delivers information about road areas usually not covered by stationary detectors, and delivers information – such as travel times – which cannot or can only hardly be collected using conventional detectors.
Meanwhile, PDA and mobile devices are becoming widespread...
PDA and mobile devices are becoming widespread and contain low cost but limited precision/accuracy builtin sensors such as GPS and accelerometers. These devices can exchange messages with nearby vehicles and RSUs by exploiting their local wireless communication interfaces.
....and can integrate the information exchanged by V2X communication infrastructure.
Even if less accurate, on-board sensors embedded in PDA can help in improving traffic surveillance especially in case of very low penetration of vehicles with full V2X capabilities,
WE HAVE A STRATEGY
We claim that tightly integrating:
- self-organizing, self-configurable, adaptive and autonomous RSUs implementing a new concept of traffic light control strategy,
- cooperative monitoring via opportunistic communications between neighbour vehicles (also at low penetration rates and by involving on-board-PDA-based wireless connectivity),
- and self-tuning feedback information about traffic state, including its accuracy estimation enables to design and implement a novel and cost-effective traffic management solution, easy and effective to be deployed from day one on.
Based on a multi-disciplinary consortium, COLOMBO’s aim is to design and implement a cooperative, self-organizing management system that
- proves that nowadays vehicular communication technology can be used for efficient – low-cost and effective – traffic and emission monitoring even if low-penetration rates of V2X-equipped vehicles are assumed;
- relies on a new concept of self-adaptive, cost-effective and automatically configured traffic light control system that has low installation cost, almost null reconfiguration costs and infinite scalability. In detail, two key objectives are considered. The first is the determination of the traffic state