Analysis of traffic sign asset management scenarios

Minimum traffic sign retroreflectivity standards proposed for the Manual on Uniform Traffic Control Devices by the FHWA will present numerous management challenges to state and local departments of transportation (DOTs) responsible for traffic sign assets. These DOTs are looking at how to comply with the standard while minimizing sign maintenance costs. This paper presents an analysis of several traffic sign retroreflectivity maintenance methods using a sign asset management simulation based on inspection and sign data gathered in the field. The simulation evaluated 30 sign asset management scenarios in terms of annual maintenance cost per sign and percentage of traffic signs not compliant with the proposed FHWA standard. The simulation results found that, generally, higher costs for sign maintenance resulted in a lower percentage of noncompliant signs. However, for some scenarios using the visual nighttime inspection method, lower percentages of non-compliant signs were found even with relatively low maintenance costs per sign. Increasing the maintenance cost per sign by 10% resulted in an approximately 10% or more reduction in the number of noncompliant signs. It is recommended that DOTs implement a 100% Type III sign replacement policy because Type I signs have a greater life-cycle cost than do Type III signs. DOTs need to allocate an adequate annual budget for sign replacement and should establish their own minimum retro-reflectivity standards. The sign asset management simulation developed as part of this study could be modified so that its use could be extended to other DOTs.