This study focuses on the impact of vehicle speed, vehicle type, pavement type, and rumble strip design (e.g., application method and dimensions) on the level of sound change that motorists perceive when they traverse rumble strips. Through data collected for this study and from previous research, it was found that sound change is based on the ability of a rumble strip design to convert kinetic energy effectively from vehicle tires into sound. The factors investigated in this study and their impact on sound change are as follows: (a) Width, length, and spacing should be adequate to allow for maximum tire displacement while the vehicle tires are traversing rumble strips. Sound levels will increase as strip width and length increase until the tires are able to obtain maximum displacement. For raised rumble strips, sound will increase as spacing increases until maximum tire displacement is reached. (b) Provided that width, length, and spacing are not limiting maximum tire displacement, sound increases as rumble strip depth or height increases. (c) Milled, rolled, button, profiled, and formed rumble strips can produce adequate changes in sound for drivers of passenger vehicles provided the appropriate design is used. (d ) Only milled rumble strips produced an adequate change in sound for drivers of commercial vehicles. (e) As the roughness of the pavement surface increases or as the speed of a vehicle increases, so does the ambient noise, which means that more aggressive rumble strip designs are necessary.a Height is relative to the distance from the pavement surface to the maximum elevation of the rumble strip and therefore will be negative for rolled and milled applications. b "Light" indicates the light private vehicles. "Heavy" indicates the heavy commercial vehicles. c If there are two dimensions, the first dimension refers to the inverted portion of the marking, and the second dimension refers to the profile portion of the marking. NA indicates not applicable, and in the case of the chipseal treatment, the chipseal is a standard design that would be louder than standard (HMA) or concrete.

Vehicle intrusion crashes in highway work zones injure vehicle occupants and workers alike, and such crashes are the concern of both state agencies and highway contractors. This paper describes the results of an effort to develop prototypical scenarios of common work zone intrusion crashes documented in the New York State Department of Transportation work zone accident database. A prototypical scenario can be defined as one that is representative of the crash process because of the typicality of its chain of events and the likely causal relationships throughout the stages of the crash. By considering the chain of events that led to a particular crash, it is possible to group similar crashes and provide a more in-depth assessment, even though some of the facts involved in the individual crashes vary. In the study described here, prototypical scenarios were developed for four intrusion crashes at four types of work zone operations: lane closures, flagging operations, mobile operations, and traffic control setup and removal activities. It was concluded that a significant portion of intrusion crashes resulted from deliberate driver decisions and actions to enter the work space. The frequency of such deliberate events, which ranged from 25% to 64%, depended on the type of work operation in place on a given roadway. The study identified between three and eight prototypical crash sequences that were not the result of deliberate actions by drivers and that led to intrusion crashes.

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Alcohol has been found to be the primary contributing factor in many wrong-way crash studies. Thus, Texas A&M Transportation Institute researchers conducted a night-time closed-course study to assess the conspicuity of select signing and pavement marking wrong-way driving countermeasures from the perspective of alcohol-impaired drivers. Lowering the sign height, making the sign larger (i.e., oversized), adding red retroreflective material to the sign support, or adding flashing red light-emitting diodes around the border of the sign did not improve the ability of the alcohol-impaired drivers to locate WRONG WAY signs in a search task. However, in post-task assessments it was the opinion of the participants that the oversized sign, red retroreflective material, and flashing lights made it easier to find the WRONG WAY sign. The participants also thought that these three countermeasures caught their attention more than the standard size WRONG WAY sign mounted at 7 ft. Researchers did not find a significant difference in the recognition time between standard and modified wrong-way arrow marking designs. The modified arrow had a narrower head that provided equivalent recognition while potentially reducing maintenance costs. The participants also similarly assessed the ease at which they could find the two arrow designs among the other markings. Thus, it appears that the modified design performed as well as the current design. Researchers recommend implementing the modified wrong-way arrow design as existing wrong-way arrows are replaced.

Many studies have been conducted to estimate the traffic safety impacts of roadway construction. Overall, the results of the analyses have varied widely, a variance traditionally attributed to site-to-site and project-to-project differences. In this paper, researchers describe an effort to use empirical Bayesian (EB) techniques to develop crash modification factors (CMFs for construction zones on the basis of temporal factors). Specifically, separate CMFs were estimated for various conditions, including time-of-day (e.g., daytime, nighttime), work status (e.g., activity, inactivity), and temporary traffic control (e.g., lane closure, no lane closure). Daily project inspector diaries from 64 freeway construction projects in four states were analyzed to determine hours of work, hours and locations of temporary lane closures, and the number of travel lanes closed during each work period. Researchers used EB methods in a before–during study design to investigate the safety impacts of the work zone conditions. Work activities that required the temporary closure of one or more travel lanes resulted in the largest CMFs (i.e., the largest increases in crashes), followed by periods of work activity that did not require a lane closure (i.e., work was occurring in the median or beyond the edge of the travel lanes). The lowest increase in crashes occurred during periods when work was not occurring at a project. The CMFs during work activity did not vary significantly between daytime and nighttime conditions when there was a lane closure. The results suggest that EB methods can be useful in assessing temporal factors that influence road safety.