Driving simulators have much to offer experimental research programs as they have the potential to provide a safe and controlled environment for testing driving performance without having to expose participants to the hazards of real world driving. However, they can also be disadvantaged if the participant's behaviour is not normal while using the simulator, that is, if the simulator fails to elicit the same stresses and responses usually elicited while driving. While validating off-road tests of driving performance would seem to be essential for any simulated driving test, it is rarely undertaken in practice. For the most part, experimental driving research assumes that the laboratory test results are relevant in terms of road behaviour. One might expect that an off-road test that has high face validity is testing on-road driving performance but this is always an assumption without first conducting a rigorous validation test. A study was undertaken on behalf of the ATSB Road Safety and the New South Wales Roads and Traffic Authority to demonstrate whether the Transport Accident Commission's Driving Simulator at the Monash University Accident Research Centre was a valid environment for testing perceptual countermeasures. In addition, it aimed to examine the effectiveness of transverse line treatments at reducing travel speed. The study was intended as a precursor to a full experimental program aimed at evaluating a range of low cost road treatments as a counter-measure to excessive speeding.