Intelligent "driver assistance" systems which utilize in-vehicle forward-looking sensors can be supplemented by vehicle-vehicle and vehicle-highway cooperative elements to comprise a "sensor-friendly" highway environment that would enhance the operational efficiency, and ultimately, the safety benefits of these systems. In our research, we have identified the current limitations of autonomous sensing systems in target/background discrimination with cluttered highways. Based upon this, and by limiting ourselves to "sensed" (and not wireless) systems, we have conceived relatively inexpensive vehicle-highway cooperative systems to allow those limitations to be mitigated. Emphasis has been placed on 77 GHz (millimeter wave) automotive radar sensors - a sensor type which is in current use and when improved, will result in improved longitudinal safety products in the near-to-mid term, up through the longer term vision of full vehicle-highway automation. In the work reported here, we introduce the concept of sensor-friendly high systems, describe roadside signatures, and using these as bases, discuss our concepting and experiments several cooperative vehicle-highway concepts. We describe experiments and results from prototypes of three of the potentially nearest term means to realize a cooperative collision avoidance systems, which we regard as the first step toward sensor-friendly highways 1 . We describe three potential systems: Light Emitting Diode Brake Light Messaging, Roadside-Mounted Corner Cubes, and Passive License Plates. We believe that while experimental results point toward the need for further proof-of-concept refinements, these systems potentially represent technologically sound cooperative vehicle-roadway components, and that indeed, "sensor friendly" systems, when put to the test, can eventually translate into significant benefit in terms of lives saved.
