- The purpose of this research was to evaluate the effectiveness of augmented in-vehicle speed warnings on driver behavior in work zones. The influence of three device configurations were examined as the drivers entered a work zone which was presented in a simulated driving environment. The first configuration was a control condition which used only traditional signage. The second condition had the addition of a visual in-vehicle warning while the final condition had the addition of an auditory in-vehicle warning. Results indicated that adding in-vehicle warnings did affect driver compliance to the work zone speed limit. Participants in the audio warning condition responded more quickly to the warning than those in the visual condition. Both augmented warning configurations differed significantly and were each respectively different from the drivers in the control condition. Based on these results we suggest a combination of in-vehicle warnings. Upon entry of the work zone we suggest a combined audio and visual warning message. However, after the initial entry phase, a visual warning message shows greater promise for the on-going modulation of driver speed transit.