Using Iterative Human Factors Methods to Assess Active Traffic Management Signing

Active traffic management (ATM) is a technique for mitigation of recurrent and non-recurrent congestion. Two ATM tools were evaluated: variable speed limits and lane control signing. An iterative human factors approach included a series of four experiments: a laboratory assessment, a field study, and two dynamic driving simulations. This paper presents the evaluation of signing for one scenario, from among several, to provide an example of the evaluation methodology. That scenario involved closing two lanes on a multi-lane freeway where the exit ramp adjacent to the closed lanes remained open. Results were consistent across experimental settings. The majority of drivers appeared to correctly comprehend the ATM signs in both static and dynamic environments. The combined results from the four experiments showed that the tested ATM signing could achieve about 66 percent driver comprehension and compliance in the presented scenario.