b1b4170c_cal_Agencies___FHWA_HRT_07_042__Reported_Impacts
[Agency/Location] USDOT Highway Safety Evaluations (14) [Comments] Conclusions based upon several years of data, but reporting process was not uniform. The data does not isolate the nature of sign improvements, so the relation to nighttime visibility cannot be determined. [Implications] Evidence that improved signing reduces crashes leading to a highly positive safety benefit. [Reported Impacts] 
Sign projects are among the highest payoff safety projects based upon evaluation reports submitted between 1978 and 1996. B/C ratio for sign projects 22.4 to 1.
Maintaining Traffic Sign Retroreflectivity: Impacts on State and Local Agencies - FHWA-HRT-07-042