关键词: |
Sign retroreflectivity, Traffic signs, Linear regression models, Expected sign life, Sign maintenance, Sign management, Retroreflectivity, Replacement, Recommendation, South Carolina Department of Transportation (SCDOT) |
摘要: |
This project investigated the degradation of traffic signs in South Carolina. Data from 1,600 SCDOT-maintained signs, collected over a nine-month period, were analyzed. The signs were selected to provide a representative sample in terms of geographic location and age. In addition to measuring the retroreflectivity of each sign, other sign data collected were: sign number, assembly number, height, offset, color, sheeting type, sheeting manufacturer, degree of shade, GPS coordinates, and sign facing direction. Both linear and non-linear regression models were developed to predict a sign’s expected life (i.e., before its retroreflectivity falls below the required minimum standard). The variables, age, and degree of shade, were found to be statistically significant for all sign colors, while the variable, northwest facing direction, was found to be significant for red signs. Based on the results of the developed regression models, SCDOT historical replacement data, and measurements taken from older signs in Spartanburg, it is recommended that the sign replacement interval be extended to 12 years. The service life of signs, especially those located in shaded areas, can be extended via washing at regular intervals. |