University of Minnesota Driven to Discover
U of MNUniversity of Minnesota
Center for Transportation Studies

Programs & Labs

ITS Sensor Header

Spring 2007

Minnesota researchers add their expertise

Photo of traffic sensors near intersection

An experimental sensor installation at a rural highway intersection in western Wisconsin. Research partnerships with other states enabled researchers to gather data under a variety of intersection conditions.

Death waits at the crossroads. Intersections make up only a small part of the U.S. highway network, but intersection crashes comprise more than 30 percent of all vehicle crashes nationwide. In rural Minnesota, crash records show that approximately one-third of all crashes occur at intersections—and research has found that failure to select a safe gap in traffic is a factor in more than three-quarters of these incidents.

Researchers from the ITS Institute’s Intelligent Vehicles Lab, the HumanFIRST Program, and the Minnesota Department of Transportation recently announced their participation in the Cooperative Intersection Collision Avoicance Systems (CICAS) initiative, a new national research effort to develop technologies that will reduce intersection crashes. The Minnesota researchers will focus on infrastructure-based solutions.

In 2002, the ITS Institute began an ambitious research effort to develop infrastructure-based technologies capable of reducing driver error at unsignalized rural highway intersections where a high-speed rural expressway intersects a low-speed, low-volume rural road. Historically, installing a traffic signal has been seen as the only recourse in locations with high crash rates, but research has indicated that adding a traffic signal to rural highway intersections often brings a new set of safety problems as well as disrupting high-speed express traffic.

The Institute’s Intersection Decision Support (IDS) research has focused on giving drivers stopped on secondary roads better information about traffic approaching on the main road. Researchers led by Intelligent Vehicles Laboratory director Craig Shankwitz have designed a sensor network that can track approaching vehicles and determine if gaps between them will be sufficient for a stopped vehicle to safely enter or cross the highway. Nic Ward, director of the HumanFIRST Program in human factors engineering, has led other researchers developing electronic signage that effectively communicates critical information to motorists. The ITS Institute has also taken the IDS concept beyond Minnesota’s borders, through a pooled-fund partnership with other state departments of transportation.

In the past two years, IDS research has accomplished several important research goals that will contribute to CICAS research, including:

  • developing advanced traffic sensor networks
  • developing an advanced vehicle trajectory measurement and recording system
  • studying driver gap acceptance behavior on a microscopic level using traffic simulation
  • testing new active displays in a driving simulator to determine what information a driver needs to safely maneuver through rural unsignalized intersections

Max Donath, director of the ITS Institute, says that participation in CICAS is a direct outgrowth of the IDS research program.

“We see this as a tremendous opportunity to build on what our researchers have accomplished in the areas of sensing and driver interface design,” Donath said. “Making vehicle-based and infrastructure-based systems work together smoothly is a challenge, but the potential payoff in terms of road safety is enormous.”

The USDOT describes CICAS as a “cooperative” system, meaning it integrates data from both vehicle-based and infrastructure-based sensing systems via the newly allocated Dedicated Short-Range Communications (DSRC) portion of the radio spectrum. Warning display systems using these data are to be developed for both in-vehicle and outside-the-vehicle placement.

Although Minnesota’s research will focus on infrastructure-based solutions, the ability to receive data directly from vehicles opens up new possibilities. For example, commercial trucks require more time for starting and stopping than passenger cars; a system that knows the size and configuration of approaching vehicles, or relevant information about the driver, would be able to tailor its responses in order to help each driver find a safe gap in traffic. Alternatively, DSRC might make it possible to shift the computation of safe gap sizes to a computer on board the vehicle itself, thereby avoiding any need to transmit data about the vehicle and driver.

Minnesota’s CICAS research, expected to last five years, will include four main components:

  1. A microscopic, in-vehicle measurement of driver gap acceptance at an instrumented intersection
  2. Alert and warning algorithms to be used to appropriately inform drivers of dangerous conditions in a timely manner
  3. A deployable sensor system used both to compute the dynamic “state” of the intersection, and to feed the alert and warning algorithms necessary data
  4. A field validation and subsequent field operational test to quantify the performance and safety benefits of such systems

The field operational test will take place at a site in southern Minnesota’s Goodhue County that has been specially instrumented for IDS research. A group of study participants will be selected to test the system under real-world conditions, using prototype driver-assistive systems installed in their vehicles.