  Safety and mission performance validation of autonomous vehicles (AVs) is a
major challenge. In this paper we describe a methodology for constructing and
applying assertion checks to validate the behaviour of an AV operating either
in simulation or in the real world. We have identified a taxonomy of assertion
types and the general format of their specification, and we have developed
procedures for translating driving codes of practice to yield formal logical
expressions that can be monitored automatically by computer, either by direct
translation or by physical modelling. We have developed examples of assertions
derived from the UK Highway Code (UKHC), as an example of a code of practice.
We illustrate the approach with an example of assertion checking for vehicle
overtaking, using a geospatial information system in an SQL database for
validation and performance assessment. We present initial simulation and
runtime monitoring experiments that apply assertions relevant in this
overtaking scenario together with an analysis of the safety and mission
performance characteristics measured.
