Susan T. Chrysler

National Survey Identifying Gaps in Consumer Knowledge of Advanced Vehicle Safety Systems

Advanced in-vehicle safety technologies are becoming more and more prevalent in the North American vehicle fleet. Market penetration of various safety technologies, including back-up camera, forward collision warning, adaptive cruise control, and blind spot warning systems, is quickly entering standard trim levels. As part of this technological expansion, more driver information and education about these safety systems is necessary to realize safety improvements. The average driver may have limited or no experience using the safety technologies. This paper reports the results of the National Consumer Survey of Driving Safety Technologies, which served as the formative research for development of a national educational campaign to encourage drivers to use their vehicle safety technologies more effectively. The research effort asked a targeted representative sample of U.S. drivers to complete the online survey. The survey collected more than 2,000 responses from this national sample and obtained information on drivers knowledge, experience, and perceptions of vehicle safety technologies, as well as their methods of seeking information about their vehicle. This paper is the first to discuss the general levels of knowledge about older and newer vehicle safety technologies in the general driving population.

Assessing Benefits of Chevrons with Full Retroreflective Signposts on Rural Horizontal Curves

Driving a horizontal curve requires a change in vehicle alignment and a potential reduction in speed. Curves may present a challenging situation during adverse conditions or to inattentive drivers. Chevron signs provide advance warning and positive guidance through the curve. Some agencies place supplemental retroreflective material on chevron signposts to enhance the signs’ conspicuity and visibility. The objective of this study was to determine any incremental benefits in vehicle speed and lateral lane position when retroreflective material was applied to chevron signposts. This study evaluated three scenarios in a before-and-after experimental design. The before evaluation presented no vertical delineation (baseline). The two after evaluations consisted of a series of standard chevrons (chevrons) and chevrons with fully retroreflective posts (full-post chevrons). Traffic counters measured vehicle speed and lateral lane position at the point of curvature and midpoint of the curve at two separate study sites. Findings showed that chevrons and full-post chevrons moved vehicles away from oncoming traffic by about 15 in. Overall, there was little difference between the lateral position findings of the two chevron treatment scenarios. Chevrons achieved a 1.28-mph reduction in mean vehicle speed from the baseline evaluation, and full-post chevrons obtained a 2.20-mph reduction. The findings determined that the benefits of full-post chevrons were not substantial. Researchers recommend that the Manual on Uniform Traffic Control Devices (MUTCD) should continue to present full-post chevrons as an optional delineation tool. On the basis of this research, the researchers do not recommend any changes to the MUTCD.

Driver performance at high speeds using a simulator

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 drivers 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.

Empirical Assessment of the Legibility of the Highway Gothic and Clearview Signage Fonts

Older drivers represent the fastest-growing segment of the driving population. Aging is associated with well-known declines in reaction time and visual processing, and, as such, future roadway infrastructure and related design considerations will need to accommodate this population. One potential area of concern is the legibility of highway signage. FHWA recently revoked an interim approval that allowed optional use of the Clearview typeface in place of the traditional Highway Gothic typeface for signage. The legibility of the two fonts was assessed with color combinations that maximized the contrast (positive or negative) or approximated a color configuration used in highway signage. Psychophysical techniques were used to establish thresholds for the time needed to decide accurately—under glancelike reading conditions—whether a string of letters was a word, as a proxy for legibility. These thresholds were lower for Clearview (indicating superior legibility) than for Highway Gothic across all conditions. Legibility thresholds were lowest for negative-contrast conditions and highest for positive-contrast conditions, with colored highway signs roughly between the two extremes. These thresholds also increased significantly across the age range studied. The method used to investigate the legibility of signage fonts adds methodological diversity to the literature along with evidence supporting the superior legibility of the Clearview font over Highway Gothic. The results do not suggest that the Clearview typeface is the optimal solution for all signage but they do indicate that additional scientific evaluations of signage legibility are warranted in different operating contexts.

Creating Pedestrian Crash Scenarios in a Driving Simulator Environment

Objective: In 2012 in the United States, pedestrian injuries accounted for 3.3% of all traffic injuries but, disproportionately, pedestrian fatalities accounted for roughly 14% of traffic-related deaths (NHTSA 2014). In many other countries, pedestrians make up more than 50% of those injured and killed in crashes. This research project examined driver response to crash-imminent situations involving pedestrians in a high-fidelity, full-motion driving simulator. This article presents a scenario development method and discusses experimental design and control issues in conducting pedestrian crash research in a simulation environment. Driving simulators offer a safe environment in which to test driver response and offer the advantage of having virtual pedestrian models that move realistically, unlike test track studies, which by nature must use pedestrian dummies on some moving track. Methods: An analysis of pedestrian crash trajectories, speeds, roadside features, and pedestrian behavior was used to create 18 unique crash scenarios representative of the most frequent and most costly crash types. For the study reported here, we only considered scenarios where the car is traveling straight because these represent the majority of fatalities. We manipulated driver expectation of a pedestrian both by presenting intersection and mid-block crossing as well as by using features in the scene to direct the drivers visual attention toward or away from the crossing pedestrian. Three visual environments for the scenarios were used to provide a variety of roadside environments and speed: a 20–30 mph residential area, a 55 mph rural undivided highway, and a 40 mph urban area. Results: Many variables of crash situations were considered in selecting and developing the scenarios, including vehicle and pedestrian movements; roadway and roadside features; environmental conditions; and characteristics of the pedestrian, driver, and vehicle. The driving simulator scenarios were subjected to iterative testing to adjust time to arrival triggers for the pedestrian actions. This article discusses the rationale behind creating the simulator scenarios and some of the procedural considerations for conducting this type of research. Conclusions: Crash analyses can be used to construct test scenarios for driver behavior evaluations using driving simulators. By considering trajectories, roadway, and environmental conditions of real-world crashes, representative virtual scenarios can serve as safe test beds for advanced driver assistance systems. The results of such research can be used to inform pedestrian crash avoidance/mitigation systems by identifying driver error, driver response time, and driver response choice (i.e., steering vs. braking).

Driving Performance and Driver Workload at High Speeds: Results from On-Road and Test Track Studies

As roadway agencies consider allowing higher speed limits, they must consider if assumptions about human performance built into roadway design formulas hold true at higher operating speeds. This paper presents a study of 14 drivers who drove both an open-road section and a test track course. The open-road route presented a natural experiment because it contained a long Interstate Highway section split roughly equally between sections with posted speed limits of 70 mph and 80 mph. On the test track, drivers were asked to maintain speeds of 60 and 85 mph for each of three nine-mile laps in which various in-vehicle tasks and a car following task were introduced in order to assess the effect of vehicle speed on driving performance. Subjective workload estimates were used for the test track tasks in addition to driving performance data. The results showed no major differences in driving performance across the different speeds tested.

Technological and Human Factor Considerations for Priced Managed Lane Traveler Information Systems

Travelers have many unique informational requirements to be able to navigate priced managed lanes. These demands often relate to specific managed lane features (e.g., access points, toll price) in addition to information about major traffic incidents and lane closures. Accommodating these needs with traditional roadway signage is a particular challenge given concerns about overloading and distracting drivers. This paper summarizes an investigation into traveler information systems for managed lanes, by considering a national review of current agency practices, a traveler survey, and an assessment for integrating advancing technologies. The national review found that many agencies vary considerably in pricing structure, number, and placement of priced destination points, and online availability of real-time toll information. A travel survey of 866 Texas-based respondents indicated that drivers prioritize information about traffic incidents and lane closures over toll price data (94% and 88% versus 41%, respectively). A higher share of respondents wanted to see travel time and incident alerts on in-vehicle devices, compared with a more statistically significant desire for destination and toll rate information on roadway signs. Most respondents use smartphone applications and mapping websites for pre-trip planning purposes (79% and 65%, respectively) compared with TV and radio reports (13%). Comparatively, prior research published 5 years earlier found that radio was a highly influential media in influencing behavior. This paper suggests a pathway for agencies to adopt a flexible approach for sharing essential data with third-party entities, based on the general transit-feed specification used for transit.

Effects of Full Matrix Color Changeable Message Signs on Legibility and Roadway Hazard Visibility

Transportation agencies are considering public–private partnerships as they struggle to fund infrastructure and operations improvements. The national Manual on Uniform Traffic Control Devices (MUTCD) allows acknowledgments of private sponsors on static signs. The legibility and visibility impacts of including logos of sponsors on changeable message signs (CMSs) were examined. Thirty drivers participated in a closed-course study during daytime and nighttime conditions. Full-sized full matrix color LED signs were used to display travel time and safety reminder messages with and without sponsor acknowledgment logos. Single- and dual-phase messages were tested. The measures of effectiveness were legibility distance for target words on the signs and roadway hazard object detection distance. Legibility distances of the CMS messages were notably greater than those of retroreflective traffic signs and well above the MUTCD threshold of 30 ft/in. During the day, the median legibility index was approximately 60 ft/in. At night, the index was approximately 45 ft/in. Sponsor logos had no significant effect on the legibility distances of travel time signs. Sponsor logos had a small effect on the legibility distance of safety message signs with a blue background but not on those with a black background. The use of sponsor logos marginally affected object detection for certain object locations. The results of this study, coupled with an earlier driving simulation evaluation showing no cognitive distraction due to logos, support the use of sponsorship acknowledgment signs on CMSs. An open road evaluation is planned before statewide implementation is enabled.

Recommended Guidelines for Nighttime Overhead Sign Visibility

Guidelines for the provision of effective nighttime performance of overhead signs were developed. Relevant policies and guidelines with regard to sign lighting currently provide little useful information to determine when sign lighting is needed, and the reference material available to practitioners is out of date. Two complementary nighttime visibility studies were conducted, which were designed to produce results useful in developing updated guidelines for overhead sign visibility. The first was conducted on a closed course and investigated the legibility distances of three sign legend and background configurations under various sign lighting treatments. The second was conducted on the open road. It investigated the effects of sign luminance and visual complexity on the distance at which a driver can read overhead signs during a recognition task. The combined findings were used to develop revised guidelines designed to provide adequate nighttime visibility of overhead signs. The proposed guidelines are based on the needs of nighttime motorists and have been formatted specifically for AASHTO’s Roadway Lighting Design Guide, which is being updated. The revised chapter on roadway sign lighting was provided to the AASHTO task force responsible for revisions. The guidelines include a list of recommended retroreflective sheeting materials that can be used to meet nighttime driver needs for specific complexity levels.

Effect of Distractions on a Pedestrian’s Waiting Behavior at Traffic Signals: Observational Study

Distraction has been a point of interest in transportation research for many years. Recently, this interest has extended from distracted drivers to distracted pedestrians. Past research suggests that distracted pedestrians are less likely to show cautionary crossing habits and tend toward increased crossing times. This study provided information about the pedestrian waiting to cross and investigated how distraction and other factors may have affected pedestrian start-up time and crossing behaviors. Researchers surreptitiously observed 760 pedestrians at three intersections in College Station, Texas, and coded their characteristics and behavior in real time. Characteristics recorded were age, gender, distraction, and grouping. Distractions recorded were talking on a phone, texting, listening to music, eating, drinking, smoking, and other. The pedestrian groups were no group (crossed alone), mixed-age group, and peer group. Behaviors recorded were glancing before entering the crosswalk, entering the crosswalk early, walking within the crosswalk markings, and hurrying across the crosswalk. Pedestrians who texted and pedestrians who talked on a phone had 21% and 31% more start-up time, respectively. Additionally, pedestrians in mixed-age groups had 14% more start-up time. Texting pedestrians were about two times less likely to glance before entering the crosswalk compared with undistracted pedestrians. Similarly, a pedestrian engaged in a phone conversation was about five times less likely to glance. These results may provide insight into ongoing discussion on how to address distracted pedestrians crossing the street.