Chapter Eight - Research Signalized Intersection Safety
Sweden is using real-time traffic models to optimize signal timings in their network. MATRIX is a real-time traffic automation system that uses a generic information and control platform. Traffic information collected from road network sensors feeds into MATRIX so that traffic signal timing plans can be managed in a demand-responsive manner.
The strategy is to compare real-time traffic data with origin/destination and assignment estimation and adjust signal timings to compensate for this variance in traffic demand. This strategy is being implemented using technology developed in Turin, Italy, and the system is still under development.20
Sweden is in the process of improving LHOVRA with SuperLHOVRA. The focus of SuperLHOVRA is heavy vehicles, which safety studies have confirmed are disproportionately involved in right-angle crashes. The system detects heavy vehicles 250 meters and 130 meters from an intersection, measures speed and vehicle length, and adjusts signal timings to reduce the likelihood of red-light running. The system has been installed at four locations, resulting in a 90 percent reduction in heavy truck red-light running. Because this system requires a large number of loop detectors, which are often unreliable, researchers are looking into cheaper, more reliable detection techniques.21
The Federal Highway Research Institute (BAST) is conducting or overseeing nearly 300 highway-related research projects. Its budget is about EUR 30 million per year. Fifty percent of the budget is spent on research projects, including about EUR 4 million on safety. BAST identified seven projects that address issues raised by the team:
Right turn on red with green arrow (1996-1999)
Tolerance toward traffic detection systems for vehicle-actuated control methods (1997- 1999)
Standardization and modular design for traffic engineering–based problems at signalized intersections, including evaluation of the use of standardized controllers (1998)
Examination of the effectiveness of interventions at existing traffic lights (1995- 2000)
Acceleration of public transport under special consideration for cyclists and pedestrians (ongoing)
Standardization of interfaces for traffic lights (ongoing)
Assurance of traffic light quality (ongoing)
The team identified a number of research efforts focused on signalized intersection safety. Dutch research shows that photo enforcement can effectively encourage user compliance and reduce vehicle speed and red-light-running violations. The Dutch are just beginning a research program with SWOV (a scientific safety board22) to determine the effect photo enforcement has had on actual safety performance metrics, such as reducing the number and severity of accidents.23
Pedestrian crossing during the red phase is an important concern in the Netherlands. The Dutch have developed several techniques to minimize this behavior. They are testing and researching additional strategies and techniques to further improve nonmotorized motorists' compliance with red signals. Several ongoing research projects involve the use of video detection to identify waiting pedestrians or bicyclists and LED countdown sensors in the pavement.
The use of dynamic, hydraulic speed bumps is being studied in the Netherlands. The height of the speed bump can be varied, depending on the speed of the approaching vehicle.
In addition, CROW is developing guidelines for pedestrians and bicycles on roundabouts.24 The Transport Research Centre 25 from the Ministry of Transport, Public Works, and Water Management is engaged in a number of research projects:
Use of rescue services to improve highway safety
Roadway work zones
Information signs and stations
TRL, in partnership with the Department for Transport, the Highways Agency, and other transportation agencies in the United Kingdom, is involved in a number of research projects focusing on signalized intersection safety. The Department for Transport is working on three research projects in 2002 and 2003:
Effects of traffic signal strategies on the safety of vulnerable road users
Safety effects of bus priority schemes
Assessment of the casualty reduction performance of local highway authorities The United Kingdom is researching new technologies to improve detection capabilities used in PUFFIN and TOUCAN crossings.