Susan T Chrysler

The Effects of Reading and Writing Text-Based Messages While Driving

Previous research, using driving simulation, crash data, and naturalistic methods, has begun to shed light on the dangers of texting while driving. Perhaps because of the dangers, no published work has experimentally investigated the dangers of texting while driving using an actual vehicle. Additionally, previous research does not clearly differentiate the dangers associated with reading and writing text-based messages. To address these issues, 42 participants drove an instrumented research vehicle on a closed driving course. Participants drove under control, text reading, and text writing conditions using a QWERTY keyboard mobile phone. Baseline text reading and writing data were also collected outside of the research vehicle. When reading or writing text-based messages, drivers exhibited reductions in reaction time that were nearly twice as great as previously thought. Drivers also exhibited nearly identical impairment in the reading and writing conditions, suggesting that both reading and writing text-based messages may be equally dangerous. These results have immediate implications for improving our understanding of the dangers of texting while driving and may be useful for future public policy discussions.

Traffic sign legibility for different sign background colors: results of an open road study at freeway speeds

Transportation agencies have been considering the use of a purple sign background color to denote that the roadway is tolled. Prior studies have shown a driver preference for a unique color for the toll road category. Concerns about the legibility of purple signs have been raised due to their brightness and contrast ratio with a white legend. The current study performed an evaluation of the legibility and recognition of purple and green freeway guide signs during daytime and nighttime driving in the Houston, TX area. Forty-eight participants drove an instrumented vehicle in open traffic and read traffic signs along a toll road with purple signs on one segment and green signs on another. Results showed no significant difference in legibility distance between signs with purple and green backgrounds. An analysis of recognition distances for advance guide signs marking ramps to the toll road also showed no difference between purple and green signs. These results support the implementation of this new color without any loss in legibility.

Driver responses to signing treatments for flooded roads

A study performed by the Texas A&M Transportation Institute for the Texas Department of Transportation examined signing strategies for warning motorists of flooding on roadways, with the goal of creating uniform signing guidelines for flooding or water-crossing situations. Two human factors studies were conducted to provide information about driver responses to signing treatments that warn of flooded roadways. The first was a series of focus groups that explored driver decision processes and information preferences related to flooded roadways. The focus group results indicated that drivers tended to base decisions about proceeding on a flooded road on their perceptions of the depth and speed of the water (which were not always reliable), as well as other visual cues; drivers preferred positive guidance in the form of directive messages and active signs. The second study was a survey that presented drivers with pictures of roadways using various signing treatments, followed by questions about how they would respond to each situation pictured. The survey results supported the focus group findings about drivers’ greater trust of active signs versus passive signs and further emphasized the effects of visual cues on drivers’ decisions about proceeding on flooded roads.

Effects of Distraction Type, Driver Age, and Roadway Environment on Reaction Times – An Analysis Using SHRP-2 NDS Data

Effects of different types of cell phone use were examined through an analysis of selected data from the SHRP2 Naturalistic Driving Study (NDS). Driving events involving lead-vehicle or approaching-vehicle incidents were analyzed to compare driver reaction times and crash probability across driver distraction type, driver age, and roadway environment. The analysis found that the median reaction time was 40.5% higher among drivers engaged in a visualmanual task such as texting, and crash risk for those drivers was 4.66 times higher compared to drivers who were undistracted. Median reaction times in urban environments were longer than those in freeway environments. Drivers aged 1619 exhibited faster reaction times then older drivers, but higher crash risk.

Transportation in an Age-Diverse Society

In our rapidly diversifying society the needs of sometimes vastly different populations must be considered. The current population is made up of a greater number of older adults, “Baby Boomers” and younger adults “Millenials” than the current middle aged-adult population. These two generations have consistently forced change on many fronts, and will continue to do so, particularly in the area of transportation. This panel is intended to address transportation research and design needs in our ever-diversifying society, from driver-interface (DVI) design to public transportation needs, from increased safety systems to the integration of technology for our navigation of various forms of transportation. Specifically, needs that might require researchers to consider the design of systems to address the sometimes conflicting abilities, desires, cultural and demographic factors, and personal goals related to age groups separated by anywhere from 20 to 60 years in age. Panelists included have a broad range of expertise working with technology, transportation, and both older and younger adult population groups.

Possible Expectancy Violations on Frontage and Conventional Roads at Interchanges: Solutions for Lane Assignment Traffic Control Signs

The intersection and mandatory movement lane control signs placed on intersection approaches are critical to safe and efficient intersection operations. Ramp, frontage road, and cross-street approaches to interchanges often widen at intersections to accommodate additional through or turn lanes. Currently, there is inconsistency in conveying to drivers how they should align themselves upstream of a diamond intersection to maneuver for their desired turning movement as the intersection widens. These inconsistencies can result in drivers making an incorrect lane selection that may result in late lane changes or illegal turns. This paper focuses on the expectancy violations that were discovered by a driver survey portion of a larger project that included practitioner surveys and a field evaluation of sign alternatives. A computer-based driver survey sampled 204 Texas drivers in four cities. The questions reported in this paper focused on driver expectations of lane movement and assignment on frontage road approaches to cross streets on freeway on- and off-ramps. Findings that showed that drivers are often incorrect in their assumptions about lane assignment when approaching intersections indicate a greater need for advanced lane control signs. A new sign design, adopted from Australian practice, that graphically shows lane additions and drops was the most effective for cases in which the downstream geometry varied from the drivers expectations.

Decision Tool to Define and Quantify Interchange Complexity

Because complexity typically is a qualitative characteristic, the ability to evaluate the complexity of an interchange objectively is somewhat difficult. This difficulty is compounded when trying to compare the complex features of multiple interchanges. A spreadsheet-based decision tool that was developed as a method for the quantification and comparison of the complexity of freeway interchanges in the United States is discussed. The initial discussion focuses on the steps that guided researchers in the development of the spreadsheet, and this discussion is followed by a description of the spreadsheet itself and how practitioners can use it to evaluate the complexity of interchanges under their consideration. A review is provided of the results researchers obtained with the spreadsheet in an evaluation of the complexity of 28 existing interchanges in 11 states. These study sites ranged from relatively simple to complex, and results indicated that the spreadsheet-generated scores were generally consistent with researchers’ qualitative estimates of the sites’ relative complexity. The meaning and interpretation of the spreadsheet results are discussed.

Investigating Speeding Behavior with Naturalistic Approaches

Although speeding is a significant contributor to traffic fatalities, attempts to address this problem have not led to a significant reduction in speed-related fatalities. There are a number of inherent shortcomings in using primarily self-report surveys and crash data to learn more about why drivers speed and in selecting countermeasures that will most effectively address speeding behaviors. An emerging empirical approach is to study the speeding choices that drivers make under everyday driving conditions by using naturalistic driving methods. Such an approach has the potential to yield highly informative data about speeding. These data, however, are complicated and prone to analytical confusion and uncertain interpretation if some key conceptual and methodological issues are not addressed. In this paper, an overview is provided of a naturalistic driving study that was intended to (a) identify the reasons why drivers speed; (b) model the relative roles of situational, demographic, and personality factors in predicting travel speeds; (c) classify speeders; and (d) identify interventions, countermeasures, and strategies for reducing speeding behaviors. The focus here is on discussing lessons learned associated with three methodological issues in particular (defining speeding, identifying a way to measure exposure, and obtaining accurate posted speeds) that were crucial to successfully analyzing the data that this study provided and for generating useful results and conclusions. It is believed that careful consideration of these issues will greatly benefit the traffic safety community, especially as future analyses of naturalistic driving data are considered.

On-the-Road Driver Behavior Experimentation Issues and Approaches

This panel addresses a research methodology that is becoming more essential for driving safety research. The methods of driving simulation and naturalistic driving have been prominent and remain important, but their limitations are becoming more evident. On-the-road experimental methods offer some of the advantages of naturalistic driving while providing a degree of experimental control and manipulation more typical of simulator experiments. Five expert researchers will discuss both scientific and pragmatic issues in the conduct of on-the-road experimentation, making use of lessons learned from their own studies. Each panelist will present a brief perspective on the problem from the point of view of their experience and expertise. This will be followed by an open discussion period.