No abstract

The goal of a Texas Department of Transportation project was a better understanding of driver performance at high speeds. Because of limited opportunity to study high-speed driving, one of the approaches used in the study was a driving simulator. The objective of the study was to measure how long drivers took to notice and react to a lead vehicle decelerating. Conditions that varied were initial speed, lead vehicle type, lead vehicle deceleration rate, and workload level. The recorded simulator data provided the research team with the driver's actual proximity to the lead vehicle at each time increment. Findings from this study included the following: higher initial speeds were associated with statistically significant longer reaction times; reaction times when following a smaller vehicle (a car in this experiment) were longer than those when following a large vehicle (a truck); brake reaction times were shorter with faster deceleration rates; and greater headways present at the start of a deceleration event were associated with longer reaction times.

For more than a decade, the proportion of American Indians and Alaskan Natives killed in motor vehicle–related crashes (per population of 100,000) has been much higher than that of other ethnic groups in the United States. Between 1975 and 2002, the number of fatal motor vehicle crashes increased by 52.5% on Indian reservations, while the number declined by 2.2% nationally. Seat belt underuse, child seat restraint underuse, and operation of a motor vehicle under the influence of alcohol have been identified as key concerns for tribal transportation safety during various tribal safety summits and in the published literature. Without detailed data, identifying specific risk factors and developing effective solutions (as well as securing federal and state funding for safety programs) is difficult. This report summarizes the information available on crashes in tribal communities to generate a fact-based understanding of the status of transportation safety within these communities. Gaps in crash data and a study procedure to overcome these gaps are discussed to understand and work better to improve transportation safety on tribal lands. Results showed that readily available information could provide only a broad overview of the status of tribal transportation safety. For the major transportation safety concerns within a tribal community to be identified and addressed, data need to be obtained at the community level. For crash patterns and best practices to be identified, information should be aggregated from tribes that have successfully established a data collection procedure and have implemented safety programs.

The objective of this study was to investigate the relative daytime and nighttime visibility of three crosswalk marking patterns (transverse lines, continental markings, and bar pairs). In general, this study collected information on the distance from the crosswalk when the participant verbally indicated its presence. The 78 participants were about evenly divided between male and female groups and between younger (<55 years) and older (≥55 years) groups. The study was conducted with instrumented vehicles on an open road route on the Texas A&M University campus during November 2009. Data were collected during two periods: daytime (sunny and clear or partly cloudy) and nighttime (street lighting on). Markings were installed for this study at nine midblock locations. The detection distances for bar pairs and continental markings were similar, and they were statistically longer than the detection distances for the transverse markings, both day and night.

A truck-mounted attenuator (TMA) is a device that attaches to the back of a work truck to help protect work crews and the traveling public from the severe consequences of rear-end crashes between motorists and slow-moving or stopped work vehicles. Although TMAs have been used by most highway agencies and contractors for many years, there are few data on the actual in-field performance of TMAs and on reductions in crash costs attributable to their use by agencies and contractors. Such data would be useful in establishing criteria on when and where TMAs must be used. An analysis of potential rear-end crashes of motorists with work vehicles in mobile and short-duration operations found that TMAs were highly effective in reducing the severity of rear-end crashes and the costs of crashes. Each crash involving a TMA resulted in a savings of $196,855 in crash costs relative to the costs that would have been incurred had no TMA been present. On the basis of current TMA prices, agencies can recoup the cost of the TMA in terms of reduced rear-end crash costs in less than a year of daytime work shifts on facilities serving 20,000 vehicles per day or more and of nighttime work shifts on facilities serving 50,000 vehicles per day or more.