The highway environment is an integral part of highway safety from the standpoints of collision causation and severity-increasing factors. Highway designers are faced with the problem of providing highway safety without sufficient information about the compatibility of current design standards with either driver or vehicle factors. Collision data collection efforts have not provided specific roadway performance data. Thus, many designs have been based on intuitive ideas rather than on specific performance information.The manufacturers of the rapidly changing vehicle fleet currently do not either provide input to the highway designer or consider vehicle-roadside appurtance interaction during the vehicle design process. This has led to the less than desired performance of some roadway and roadside design features.This paper identifies the problems faced by the roadway designer, and gives suggestions for solving these problems with real-world roadway performance data.