Task Order 5600
Transportation Safety Research


Intersection Decision Support

Jim Misener
California PATH
University of California, Berkeley

Summary

The California approach and contribution to the overall three-State Intersection Decision Support (IDS) program is perfomed by TO 5600. It stems from a systems-oriented and top-down perspective. It is tempered by the need to provide real solutions for a likewise real "point of departure" crash type. Hence, the TO 5600 at once addresses:

  • Left turn movements, and in particular what is dubbed Left Turn Across Path/Opposite Direction (LTAP/OD), shown in Figure 1, and Left Turn Across Path/Lateral Direction (LTAP/LD), urban scenario, shown in Figure 2. According to the 1998 GES (National Accident Sampling System (NASS) General Estimates Sytem (GES): Analytical User's Manual 1988 - 1999. National Center for Statistics and Analysis, NHTSA, U.S. Department of Transportation) and Smith and Najm (Smith, D.L. and Najm, W.G. 2001. "Analysis of Crossing Path Crashes for Intelligent Vehicle Applications." 8th World Congress on Intelligent Transport Systems, Sydney, Australia, October 2001. Paper No. ITS00533) the LTAP/OD scenario represents 27.3% of intersection crashes and cuts across all causal factors. Likewise, the LTAP/LD scenario represents 15.9% of all intersection collision types. Even when delimiting the LTAP/LD to urban areas, we believe that our specific solution approaches may affect between 30 and 40% of all intersection crashes in the U.S.
figure 1

figure 2
  • Our original systems approach which more generally addresses the national problem to lead to a "best" nationally interoperable solution.
In defining this "best" IDS, we recognize that several potential dimensions may be important. These dimensions include:
  1. multiple views on the size of problem (be it by crash frequency, severity or fatality);
  2. grouping of cognitive or engineering causal factors,
  3. solution approaches that can be addressed by certain technologies, and finally
  4. what can be cost-effectively deployed, in the near-term and also in the longer term.
Our work plan addresses these tradeoffs, and in the end, we will arrive at a definition of a nationally interoperable IDS solution and an appropriate FOT.

Hence, as a necessary in-depth supplement to the top-down systems approach, we will also investigate key enabling technologies, most notably cooperative infrastructure-to-vehicle (or vehicle-to-infrastructure) and vehicle-to-vehicle communication. We will also conduct naturalistic driving data collection, perform driver modeling, develop an integrated IDS simulation approach, and look at the applicability of a large set of already- or nearly-available "commercial off the shelf" systems toward meeting IDS requirements. We are also investigating the use and usability of roadside-mounted dynamic message signs.

Along the way, we will perform analyses, experiments, design and planning to allow US DOT and the Infrastructure Consortium to have a lasting stamp on the life-saving IDS systems that are deployed by the year 2010 and beyond.

Our research plan is constructed to realize, in three years, the requirements, tradeoffs assessment, and technology investigations necessary to define an IDS. Toward the end of our three-year program we will combine our understanding of the problem definition, IDS technologies and our integration experience with a standard Caltrans intersection (with advanced traffic controller) and design an IDS system that can be field tested, as a first step toward deployment.

A highlighted feature of our experimental approach is that we will leverage a significant Caltrans investment in installing a four-way signal controlled intersection at our Richmond Field Station facility, where we will primarily work on human factors experiments, verification of warning system effectiveness, and communication hardware and protocol development.

Our contributions, therefore, are systems engineering, to include significant contributions to problem definition, tradeoff studies, and the like. We will also provide significant contribution in key technical areas, to include wireless communication, roadside messaging, driver modeling, and simulation. We will crystallize our contributions with LTAP/OD and LTAP/LD example applications, which will serve as our point of departure in determining the "best" national solution.

We will also "deliver" a test intersection, and its results - "proof" that ad hoc networks of vehicles can be individually addressed to talk to intersections and vice versa. Finally, we will develop a plan to implement these in a California intersection within the description of our FOT.