b1b4170c_cal_Agencies___FHWA_HRT_07_042__Reported_Impacts
[Agency/Location] Mendocino, CA (15) [Comments] This study relied on CHP data which covered a ten year period. There was a limited number of sections, but the safety experience of State roads in the area were used as a control. The effects of signing and marking improvements was not isolated. [Implications] Some skepticism is needed relative to the order of magnitude of the benefits, but it there would seem to be ample evidence of the value of good delineation and signing. Detailed of the review process and reasons for 3 year frequency should be pursued. [Reported Impacts] 
Road safety reviews which focused on sign and markings led to crash reductions savings in excess of $11 million. B/C ratio of 1:159 reported. Program cost were approximately $160,000, but calculated crash savings ranged from $12.8 to $23.7 million.
Maintaining Traffic Sign Retroreflectivity: Impacts on State and Local Agencies - FHWA-HRT-07-042