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|Federal Highway Administration > Publications > Public Roads > Vol. 65 · No. 1 > International Cooperation to Prevent Collisions at Intersections|
International Cooperation to Prevent Collisions at Intersections
by Cathy Frye
The United States and Japan have joined forces in the hope of finding technology-based solutions to reduce the high incidence of crashes at intersections. Teaming together for the new U.S.-Japan Intelligent Transportation Systems (ITS) Joint Research Program, both countries are exchanging information and discussing solutions being developed, evaluated, or implemented in their respective nations.
The ITS Joint Research Program was initiated in November 2000 in Turin, Italy, during the 8th Workshop on ITS in the United States and Japan. The workshop was held in conjunction with the 7th World Congress on Intelligent Transport. The workshop participants laid the groundwork for the future cooperative study and agreed that their long-range research topic will be the evaluation of the effects of infrastructure support for intersection collision avoidance (ICA). In addition to exchanging progress reports throughout the year, Joint Research Program participants will hold an annual meeting to review findings.
Each year, both countries will focus on one research subtopic for study. The topic for 2001 is systems concepts and requirements for infrastructure support for ICA.
In the spirit of "two heads are better than one," both countries will take this opportunity to look at solutions that are aimed at reducing the number of crashes at intersections in the United States and Japan. Because the two countries frequently take different approaches to resolve the same problem - too many accidents occurring at intersections - the Joint Research Program is a learning experience for all involved.
To further advance the Joint Research Program's information exchange, Japan is sending an engineer to the Turner-Fairbank Highway Research Center each year on a fellowship. Having a Japanese research fellow at the Federal Highway Administration's (FHWA's) center for research, development, and technology helps in the day-to-day informal exchanges of information. Both countries are excited about the potential advances in intersection collision avoidance that could come from this cooperation.
At the Cross Roads or in the Cross Hairs?
According to the International Road Traffic Accident Database, an estimated 10 million traffic crashes worldwide occur each year, and these crashes claim the lives of one-half million people. Sixty percent of the crashes occur in the United States, and of those, 27 percent of the crashes in the United States occur at intersections. Intersection crashes are in a statistical dead heat with rear-end collisions, which account for 28 percent of all crashes on U.S. roads, as the second most common type of crash occurring on our roads. This makes intersections "among the most dangerous locations on U.S. roads," according to FHWA's ITS Joint Program Office.
In Japan, intersection collision statistics are even more staggering; more than 58 percent of all traffic crashes occur at intersections. Thirty percent of all Japanese traffic accidents involving fatalities occur at intersections, and the majority of these fatal crashes happen at intersections without traffic signals.
Intersections Present Unique Problems
The crash statistics from both the United States and Japan clearly show the dangerous nature of intersections. Intersections are far more complicated than other roadways, such as a divided highway where all of the traffic on each side of a median is flowing in one direction. Since an intersection is a decision point for vehicles from multiple directions, many variables are at play. Vehicles may need to stop, start, yield right of way, slow, accelerate, or turn. Drivers may purposefully ignore traffic signals - as is often the case with red-light running - or simply misunderstand them.
Intersections present the ideal environment for crossing-path crashes in which both vehicles are initially traveling from either perpendicular or opposite directions and then one vehicle cuts across the path of the other. There are four types of crossing-path crashes:
In addition to vehicular crashes, pedestrian accidents in intersections are also a problem. In the United States, 70,000 vehicle-pedestrian collisions occur annually, and 40 percent occur in intersections. More than 45 percent of all pedestrians hit by vehicles in Japan are struck in an intersection, and an astonishing 52 percent of these incidents occur while the pedestrian is in the crosswalk.
The Weak Link
Surprisingly, the cause of most crashes is not adverse road conditions, driving under the influence, or even vehicle defects. In the human-machine collaboration that occurs during driving, the weak link is often the human. Driver error is the cause of 90 percent of all police-reported car crashes in the United States.
Preliminary study data from the ITS Joint Program Office indicate that with the full deployment of just three Intelligent Vehicle Initiative (IVI) systems, one in every six U.S. crashes would not occur. IVI systems are being designed to enhance human performance and guard against human shortfalls such as limited sight distance and reaction times that are not fast enough to keep a crash from happening.
Emerging Intelligent Vehicle Systems
U.S. research is looking at collision countermeasures. Initially, these could be infrastructure-only systems that rely solely on roadside warning devices to signal drivers. Ultimately, the emerging systems could evolve into cooperative systems that communicate information from the infrastructure directly to vehicles and drivers.
For example, a countermeasure aimed at reducing red-light running could use sensors to identify potential traffic-signal violators by determining the speed and the deceleration rate of each vehicle at a fixed location before the traffic signal. Once a potential violator is detected, a roadside warning device could display a warning with flashing lights to "stop ahead." This infrastructure-only system might make use of magnetic loop detectors, self-powered vehicle detectors (SPVDs), optical sensors, or radar sensors in addition to a variable message sign - all currently available off-the-shelf products.
With a future cooperative system, instead of relaying a warning to the driver through the use of a variable message sign, a warning could be communicated directly to the potential red-light runner inside the vehicle via a message console, an audible warning, or other sensory warning. With refinement, cooperative systems could detect the vehicle, determine that it is approaching the intersection too fast to stop, and assume control so that it is stopped before potentially causing an accident at the intersection.
Although the potential to develop cooperative road-vehicle systems exists, this capability is a controversial development in the evolution of human travel. It brings with it potential liability issues in the event of a system failure, and it requires a general change in thinking that the human driver should always be solely in control of the vehicle.
Other potential systems that may be coming off the American drawing board include "smart stop signs." These smart stop signs, like the already described red-light-running countermeasure, could use conventional magnetic loop detection, optical sensors, or radar sensors to reduce the number of crashes that occur near U.S. stop signs each year - currently, about 79,000 crashes per year. Not only would the potential violator be notified before missing the stop sign, but warnings could be conveyed to drivers on adjacent approaches to the same intersection. In this way, even drivers with the right of way would be alerted to avoid a crash.
But the danger of a collision at an intersection controlled by stop signs is not just a result of a driver who fails to stop; sometimes, after stopping, a driver fails to yield the right of way. How often have you been at a four-way stop when one driver mistakenly took the right of way? Poor judgment regarding right-of-way decisions adds another 362,000 collisions per year in the United States.
More complex than identifying potential stop sign runners, stop sign "movement assistance" to identify right-of-way priority would require algorithms that "must model vehicle movements at the intersection based on the results of individual driver decisions, distill opportunities for individual vehicles to move, and then control messaging to drivers that will effect movements with extremely high reliability," said Bob Ferlis, team leader of the Enabling Technologies Team for FHWA's Office of Operations Research and Development.
If just installing a traffic signal at the intersection sounds like a simpler solution, think again. These intersections would already have traffic signals if they were warranted.
A similar approach can be taken to create a countermeasure to crashes that occur when a vehicle is making a left turn and is struck by a vehicle approaching from the opposite direction and moving through the intersection at a relatively high rate of speed. This countermeasure would be designed to determine the speed and acceleration or deceleration of each vehicle approaching the intersection from the direction that is opposite a potential left-turning vehicle. Here, research pushes the limitations of available technology as sensors to measure both speed and acceleration are not yet commercially available. This is also why looking at technology applied in other countries such as Japan may have big payoffs for U.S. research and development efforts.
In Japan, several intelligent vehicle innovations are already being field tested or are currently available. In addition to intelligent cruise-control systems that maintain a set interval between vehicles, there are several interesting applications of collision-avoidance systems. The same type of vehicle sensors that are used in the intelligent cruise-control systems were employed in Japan to avoid rear-end collisions.
The Japanese also have what they call "Stop & Go" systems, which are designed for operating vehicles in heavy traffic congestion. Using Stop & Go, the driver controls the accelerator, but the system controls the brakes to maintain a safe following distance from the vehicle ahead. "It's like a very slow-speed cruise control," said Paul Olson, ITS specialist at FHWA's Western Resource Center in San Francisco.
The 9th Joint U.S.-Japan Workshop on Advanced Technology in Highway Engineering and "Smart Cruise 21 - Demo 2000," a demonstration of Japanese ITS systems, were conducted in Tsukuba, Japan, Nov. 28 to Dec. 1, 2000. Members of the U.S. delegation to the workshop observed the most recent Japanese ITS developments.
The Japanese are researching and developing other systems that rely on roadside sensors as well as in-vehicle sensors. A system known as VICS (Vehicle Information and Communications System) collects traffic information and puts it on the Internet to be broadcast to complex roadside variable message signs and to in-vehicle navigational devices. The traffic information collected from the roadside sensors is transmitted to in-vehicle devices using overhead-mounted infrared devices.
The communication is two-way between the vehicle and the roadside. The roadside sensor sends information on congestion to the vehicle, and the vehicle sends information on vehicle speed and identity to the central computer systems. The central computer systems use the information to detect and predict congestion. The in-vehicle devices also receive information over FM radio channels and the antennae for the FM part of the system are quite distinctive.
In Japan, in-vehicle navigation systems are very popular and about 60 percent of the in-vehicle navigation systems are VICS-compatible. By March 2001, approximately 2.8 million automobiles in Japan were equipped with VICS receivers, and VICS service is available in 28 of Japan's 47 prefectures (provinces) and on all Japanese expressways.
Using Intelligent Vehicle Technology to Avoid Crashes Waiting to Happen
When one vehicle runs a red light and hits two others in an intersection, it is a senseless human tragedy. Frequently, witnesses watch vehicles collide as if in slow motion, but remain helpless to warn oncoming vehicles. The U.S.-Japan ITS Joint Research Program promises to create countermeasures to avoid many of the crashes that are just waiting to happen. The countermeasures will assist humans in seeing the dangers ahead, provide warnings before it's too late, or create intelligent vehicles and roadways that will protect us from the human errors that often lead to collisions.
Intelligent vehicle (IV) technology can augment human senses and reflexes and provide drivers with warnings in enough time to stay safe. Done right, it's like having an angel on your shoulder.
Despite all the promise of IV technology, researchers remain cautious and highly conscious that effective warning devices will require substantive human-centered research and experimentation to ensure that the warnings are clear and do not provide drivers with additional distractions. Just like cell phones, which have enhanced safety by allowing motorists to call for emergency aid more quickly than ever before, all gadgets placed inside the vehicle can potentially distract the driver. In-vehicle, high-tech additions require an interesting balancing act. Is the newest gizmo a potential lifesaver or a dangerous distraction? Alerting drivers to unsafe situations that they cannot see or predict down the road would be a powerful tool to reduce crash rates as long as the devices do not provide the human brain more information than it can handle while maintaining control of a vehicle.
To guard against creating hazards instead of eliminating crashes, researchers in both countries agree that human-centered considerations play a large role in bringing emerging IV systems to market. Researchers are also aware that it will take time for drivers to adapt to the new high-tech systems and new rules. The specifics pertaining to designing collision countermeasures, introducing collision-avoidance systems on public roadways, and determining which countermeasures work best in particular locations are all complex issues for which "two heads [or two countries working together] are better than one." Both countries intend to learn from each other's successes and failures.
Robert Ferlis. Infrastructure Systems - Intersection Collision Avoidance: Overview of Concepts, Federal Highway Administration, Washington, D.C., March 2001.
Cathy Frye is the founder of The Fresh Eye, a woman-owned sole proprietorship established in 1994 to provide writing, editing, and publications management services. She holds a degree in writing from Johns Hopkins University and has more than 20 years of experience as a writer and editor. She has worked on various FHWA projects in the past, including the 1997 and 1998 Research and Technology Program Highlights reports.
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