Congestion is a growing problem in many European cities. Local authorities are looking to new technologies for traffic management as one means of tackling this. Moreover, regulating the traffic flow may reduce vehicle emissions, and giving priority to buses may foster a modal shift to public transport. These benefits are expected to be greater through the integration of multiple systems, such as urban traffic control and driver information. However, there is limited evidence on the real-life performance of such systems on which to base investment decisions.
The goal of INCOME was to provide decision-useful information on the performance of integrated urban traffic management systems (UTMS) combining urban traffic control (UTC), public transport management systems (PTS) and driver information systems (DIS).
Various combinations of UTMS components were tested and evaluated through simulation studies and field trials in London, Piraeus, Turin and Gothenburg. A guidebook has been compiled for transport managers and local authorities, summarising the results, infrastructure requirements, factors affecting the benefits, and other implementation issues.
Highlights among the wealth of quantitative results were:
- Public transport priority in UTC. Public transport achieved journey-time savings of around 5-15% across three cities and similar improvements in journey-time reliability. In all cases the payback period was less than two years.
- Integration of UTC priority and automatic vehicle location for buses. This allows selective priority to be given to buses that are running late, thereby improving reliability. Predicted improvements in bus regularity and in passenger waiting times are around 10%.
- Bus gating at traffic signals. This involves holding back queues of private vehicles at traffic signals on strategic routes, allowing buses to overtake along segregated bus lanes. The bus lanes doubled the savings in bus delay compared to bus priority alone at traffic signals.
- Integration of UTC with variable message signs (VMS). These applications transferred data from UTC to VMS. The clearest benefits came from the earlier re-routing of traffic in response to incidents, activated by the automatic incident detection function of a UTC, increasing drivers' journey-time savings due to the VMS from 23% to 28%.
- Intelligent speed adaptation. This is a new in-vehicle technology aimed at reducing or preventing speeding, which can be integrated with UTC systems. Simulation results indicated a 50% reduction in accidents at speeds above 45 km/h, and speed reductions of up to 20%.
- Integration of PTS and DIS. Variable message signs can be used to suggest alternative routes to encourage drivers not to use important bus routes in congested areas. Simulations showed that reductions in bus delays could exceed 20%, although this is dependent on the local situation (e.g. if the alternative routes are also bus routes, the net benefits can be negative).
- Fully integrated traffic management systems (UTC, PTS and DIS). Sharing of data and control signals between sub-systems in Turin has reduced travel times for both general traffic and public transport by 20%, with an accompanying modal shift of 3% to public transport. Local pollutant emissions w
Urban traffic management systems are one of the key tools under the control of city authorities that can be used to support local policy objectives for mobility and the environment. Moreover, they can be implemented in the short term. INCOME has provided evidence of the additional benefits that can be achieved by using advanced systems in an integrated way.
Nevertheless, one of the lessons from INCOME is that the benefits must be estimated for the local situation. For example, public transport journey-time savings are dependent on congestion levels and the number of traffic junctions where systems can be used, and heavy congestion reduces the scope for some forms of bus priority. Simulation can provide a cost-effective means of screening alternative solutions prior to pilot-scale or full-scale implementation.