Stackhouse, Stirling

This final report covers the first phase of a research project to evaluate the effectiveness of selected traffic calming implementations in Richfield, Minneapolis, and Bloomington. The project's first phase included the development of criteria for traffic calming applications and the application of those criteria to sites in the above three cities. As one way to involve citizens in selecting traffic calming options, researchers also completed a survey of residents in Richfield and Minneapolis. Researchers also calculated traffic volumes for Richfield. City engineers selected the following sites for the project: residential areas in Richfield and Bloomington and a crossing of Willow Street in Minneapolis, which connects the Greenway with Loring Park. Each city plans to use the following techniques: buildouts or "blisters" in Richfield, a raised and striped platform in Minneapolis, and a no-left-tum sign for peak hours in Bloomington. The report also includes a comprehensive annotated bibliography on traffic calming. This report is unpublished. 15 copies were produced and distributed.

This report presents the results of a one year comprehensive human factors analysis on the Volvo Dynaguide Mapping system and the Indikta Voice messaging devices supplied by the Minnesota Department of Transportation. RBDS-TMC devices provide a means of transmitting traffic information to motorist using the existing Traffic Management Center's (TMC) resources. This study examined the devices and the means of transmitting information using ergonomic and human factors principles. This study expanded upon the functions of these devices and their ability to transmit information, as well as their integration within the automobile. Further we examined the message assembly software and the resultant messages delivered to the end users. To complete this study we completed a feasibility of on-road study methods, and surveyed the TMC control room staff as to their desires and needs in workplace design and management. Six tasks were completed with the following findings: Ergonomically, both devices require further refinement to provide a user friendly interface. Linkage analysis and flow charting extracted areas where operation of the device was impeded by design as well as highlighting the many positive features of each device. Simulation study elicited the need for further examination of user preferences and the need to use a wide age-based study group. This was evident in the differing opinions of younger versus older drivers. Assessment of the message assembly program and delivered message content revealed several areas of needed refinement, including beta testing of the outputs of the devices with the message assembly software. Finally, an on-road protocol feasibility study was completed and a workplace assessment was completed at the TMC control room.

This project examined grade crossing safety and human factors through a variety of research methods: focus groups, a telephone survey, a literature review, and an analysis based on a new approach by Neil Lerner. Learner notes that drivers should not be treated as reckless, inattentive speeders. Instead, they should be considered decision makers who use information of limited quantity and quality against a background of knowledge shaped primarily by their experience of trains rarely appearing when they cross. Researchers found no evidence that additional education programs or public awareness campaigns had any lasting effect on the frequency of grade crossing accidents. Researchers also found no evidence suggesting that bigger or brighter or other modifications of traditional signs or signals led to favorable changes in drivers' behaviors at grade crossings. The report concludes that using available sensor-processor-message display technology, configured in a way to promote improved driver decision making, offers the potential for grade crossing accident reduction. Researchers recommend additional studies to investigate this potential for grade crossing accident reduction.

This project sought to understand the effects of warning flashers on the safety of rural intersections. Researchers conducted four separate studies: a literature review; an opinion survey of a sample of Minnesota motorists who lived outside urban areas; an analysis of accident data for rural intersections comparing accident rates three years before and three years after the installation of various configurations of warning flashers; and a field study at the intersection of U.S. 14 with MN 52 in Eyota, Minn. This last study included a baseline period, followed by a phased implementation of various warning flasher configurations, with a week or so between phases. Researchers concluded that none of the four studies unequivocally supported the effectiveness of warning flashers at rural intersections in promoting safety at rural intersections. While driver alertness or awareness to potential hazards at the intersection may have been enhanced by the installation of warning flashers, this project did not provide data that would demonstrate such enhanced alertness or awareness.

This research established a concise set of human factors guidelines for evaluating devices and also assessed the Genesis project's message format suitability. It provides a literature review and synthesis of human factors relating to the use of devices, such as cellular phones, pagers, and car radios, and to other tasks that drivers may undertake while driving. The work revealed that the use of information-providing devices such as pagers or PDAs will increase information processing workload; that the findings from the use of a particular device under particular conditions cannot be generalized to other devices or conditions; and that only empirical findings will show whether and under what conditions reading traffic information displayed on pagers or PDAs will seriously degrade driving performance. Work on message format evaluation showed that message formats could be improved and that improvement would result in better legibility and comprehension and decrease the time a driver would attend to the display.

In a road research project, older drivers were asked to read street names as soon as they were able as they were approaching an intersection. The signs were always on the far sides of the intersection but could be either on the right or left side. Intersections of three levels of complexity were used. A repeated measures design was used. All main effects and all but one of the interactions were significant. The legibility distances obtained from 864 trials using 18 subjects showed that Diamond Grade and VIP Diamond Grade sheeting were equivalent but that both were significantly superior to High Intensity Grade sheeting which was in turn significantly superior to Engineering Grade. The differences among sheeting grades were more apparent at the more complex intersections. The viewing conditions on some of the streets resulted in reduced visibility and conspicuity causing markedly reduced legibility distances. There were no performance differences based on gender. The implications for driving safety were discussed in the context of visual information processing workload, divided attention and multitasking.

Drivers often perform tasks alone or in combination that don't relate to control of their vehicle. This experiment evaluates the impact on simulated driving of performing non-driving tasks. The results showed that some of these tasks significantly degraded driving performance. The task that required drivers to use the map device caused the greatest problem. In addition, older drivers performed less well than younger drivers. The study shows objective reasons for evaluating the trade-offs between maximizing traffic safety and providing drivers with information that requires a high degree of visual attention. In the experiment, drivers performed the following secondary tasks alone, as pairs, or all three simultaneously: talking on a simulated cellular telephone, finding an object in an enclosed container, and using a special radio with head-up map and text displays. The experiment required drivers to maintain speeds of 25 to 30 miles per hour, keep the car centered in their traffic lane, and respond quickly to the appearance of simulated brake lights. Researchers divided subjects into four groups of 10 members each: young females and males with an average age of 31 and older females and males with an average age of 70.

This report presents data using multiple-choice questionnaires to learn how drivers respond to traffic information in the form of advisory messages. Two experiments, comprising 112 participants, were conducted using the same technique and yielding similar results. The traffic information messages presented to participants varied in three respects; quantitativeness of information, imperativeness of advice, and timeliness of information. Two additional factors were examined; the amount of traffic congestion stated to be directly observable on the route and the stated accuracy of messages received in the past. Results obtained from the questionnaires indicate that the structure of the traffic message did influence the driver behavior. The propensity to depart from the planned route ahead of schedule was greater when respondents had; few exit options remaining, been told traffic levels were high, received accurate traffic information in the past, and had received messages which contained quantitative and/or imperative information. Traffic controllers with this knowledge of driver behavior could act to further reduce trip times and congestion by using the control tools currently available to them. The major conclusion we can draw from this study is that when possible and appropriate, advisory messages should contain accurate, timely, quantitative and imperative information.

The success of in-car devices that aid drivers depends in part on driver reaction and acceptance. This project looks at the human factors considerations for the GENESIS Program, which studies the use of personal communication devices to deliver real-time traffic and transit information services. Researchers used vehicle simulation to learn more about the impact of the use of GENESIS devices. The report includes a discussion of human factors issues for consideration during the operational test evaluation phase and recommends suggestions to improve in-car computer screens and for future simulation studies.

This report presents the results of a one year comprehensive human factors analysis on the prototype Delco RDS device supplied by the Minnesota Department of Transportation. RDS devices provide a means of transmitting traffic information to motorist using the existing Traffic Management Center's resources. This study examined the devices and the means of transmitting information using ergonomic and human factors principles. This study expanded upon the functions of these devices and their ability to transmit information, as well as their integration within the automobile. The study was completed by examining the data entry tasks required to transmit messages and the TMC's operations as pertaining to messages and delivery to the end-users. Five tasks were completed with the following findings: Ergonomically, the prototype device requires further refinement to provide a user friendly interface. Linkage analysis and flow charting extracted areas where operations of the device was impeded by design. Simulation and on-road study elicited difficulty in operating the device while maintaining driving proficiency. Highly significant deviations were found between normal driving behavior and driving performance when simultaneously operating the device. This suggests an increase in attentional demand which is placed on the driver operating the device when they should be focused on the task of driving. Finally, assessment of data entry personnel and the TMC operations found several areas for improvement in the Crusader (TM) message assembly program interface and message content. Recommendations are provided following each task.