Determining Optimal Deployment Location of Portable Changeable Message Sign Upstream of Work Zones

A portable changeable message sign (PCMS) has been utilized in the upstream of work zones for many years. However, the Manual on Uniform Traffic Control Devices (MUTCD) does not specify the optimal deployment location of a PCMS in the work zones. Thus, traffic engineers have to rely on their experience to determine the deployment location for a PCMS. As a result, the potential effectiveness of a PCMS may not be fully realized. The objective of this research was to determine the optimal deployment location of a PCMS in the upstream of work zones with the purpose of effectively reducing vehicle speeds. To achieve the objective, two field experiments were performed. The first field experiment was conducted to determine the vehicle speed profiles when a PCMS was placed at three different locations from the start point of a work zone which was the location of the first temporary traffic control sign (W20-1 Sign). Based on the results of speed profile analyses, it was found that vehicle speeds declined smoothly and had the least speed variances when a PCMS was placed near 575 feet away from the W20-1 Sign. To verify the outcomes, the second field experiment was conduct in which a PCMS was placed at 750, 575, and 400 feet away from the W20-1 Sign. Based on the results of regression analyses, the authors concluded that the optimal deployment location of a PCMS in the upstream of work zones was anywhere between 556 to 575 feet away from the W20-1 Sign.