Transportation agencies are responsible for maintaining traffic signs, a critical part of any transportation network, in a satisfactory condition. This is achieved by the implementation of sign maintenance and replacement strategies. This paper presents the results of a sign replacement simulation model based on the Blanket Replacement method. Although the case study described here was based on North Carolina (NC) sign data, its results provide insights for all transportation agencies about effective practices that result in cost-efficient sign replacement strategies. The authors found that daytime inspections reduce the number of unsatisfactory signs while having little effect on cost. Grace periods were found to be efficient in reducing costs. Longer replacement cycles (e.g., 20 years) that consider daytime inspections and a grace period resulted in more cost-efficient strategies than those with shorter replacement cycles (e.g., 10 years).
Although several studies have assessed the effect of business logo sign format on driver visual attention and performance, some concern has been expressed that findings may not be generalizable to other signage configurations. We conducted a driving simulation study to assess the effect of distance guide sign format on visual attention allocation, target detection accuracy, and driving performance considering driver demographics. Results revealed distance guide sign format, including random or distance-ordered presentation of destinations, to have no impact on driver visual attention, target identification, and vehicle control. However, elderly drivers had difficulty in identifying targets when destinations were presented in random order. In addition, elderly drivers exhibited conservative responses (i.e., reduced off-road visual attention and greater speed reductions) as compared to other age groups when exposed to distance guide signs. Findings support design guidance for on-road signage to account for driver demographics.
The standard business logo sign found along North Carolina highways contains six logos, in accordance with the Manual on Uniform Traffic Control Devices. As the population grows, the demand for business is increasing. Shifting from six-panel business logo signs to nine-panel signs would afford more businesses the opportunity to advertise in areas of high demand. The effects that such a change may have on the driving population are analyzed. Factors such as a driver’s age and familiarity with logos and logo format are taken into consideration. A change in the format of business logo signs is proposed not only to move from six to nine panels but also to improve the effectiveness of existing business logo signs.
Traffic signs play a major role on the national highway system because they provide users with important information such as warnings, regulations, and directions. To ensure sign visibility at night, the Manual on Uniform Traffic Control Devices (MUTCD) requires transportation agencies to meet minimum sign retroreflectivity levels through a sign maintenance program. To better understand current trends, the researchers conducted an extensive literature search that showed that expected sign life and nighttime inspection are the most used methods, followed by blanket replacement. The literature does not typically discuss how these methods are implemented. Thus, the research team also contacted three of the four largest state-maintained highway systems in the United States (North Carolina, Virginia, and South Carolina) to discuss sign maintenance programs, implementation issues, and best practices. The authors describe in this article the findings and conclusions drawn from these case studies that may help other agencies improve their sign maintenance practices.
Previous studies have empirically assessed the effect of on-road signage on driver distraction and attention allocation through eye-tracking measures and driving simulations. However, state and federal agencies might be able to make use of simpler approaches to determining the potential visual load of on-road signs. This study compared different on-road signage (food, gas and attraction, and distance guide signs) with respect to visual salience, assessed the effect of the number of panels and logo format on signage salience, and analyzed associations between salience values for different sign types with target detection accuracy and off-road glance duration. Visual salience of signs was measured with the salience using the natural statistics (SUNs) method. For correlation analyses between sign salience, attention allocation, and detection accuracy, a sample of 120 drivers participated in two driving simulation studies. Results revealed food business signs, containing all pictorial logos, to be more salien...
