This paper reports some initial observations as we explore the hypothesis that ontologies can be used to improve the capabilities and performance of on-board route planning for autonomous vehicles. We are in the early stages of an effort to evaluate the performance of ontologies in different components of our chosen infrastructure: the 4D/RCS system architecture developed at NIST. Our initial focus has been on simple roadway driving scenarios where the controlled vehicle encounters potential obstacles in its path. As reported elsewhere, our approach is to develop an ontology of objects in the environment, in conjunction with rules for estimating the damage that would be incurred by collisions with the different objects in different situations. Automated reasoning is used to estimate collision damage; this information is fed to the route planner to help it decide whether to avoid the object. We describe the issues and insights developed during the first phase of the project and discuss the changes to our approach that have resulted.