Bloomfield, John R.

After visiting a variety of stop-controlled intersections in the Twin City metro area, the researchers developed, with the aid of a computer simulator, two innovative intersection designs to improve safety at unsignalized intersections on four-land, divided highways. These innovative designs offer a number of advantages; however, due to funding difficulties, the researchers were not able to test the effectiveness of the designs in a real world setting.

The Minnesota Speed Management Program (MSMP), a cooperative project between the Minnesota Department of Transportation and the Minnesota Department of Public Safety, was developed within the framework of the Minnesota Comprehensive Highway Safety Plan. The overall goal was to reduce the number of fatal and lifechanging crashes on Minnesota highways. The MSMP involved a speed limit adjustment—on 850 miles of Minnesota’s 55 mph highways the speed limit was increased to 60 mph. It involved increased speed enforcement—by State Patrol, county sheriffs, and local law enforcement—on selected highways. There were four waves of Enhanced Enforcement (one of six weeks, three of eight weeks) each followed by four weeks of Regular Enforcement. The MSMP involved extensive public education, organized by the Office of Traffic Safety, with approximately 10,000 public service messages presented on the radio. Two evaluation efforts were conducted. The University of Minnesota compared travel speed data and crash data obtained during the MSMP with historical data. Throughout the MSMP, there were decreases in the number of drivers traveling at least 10 mph above the speed limits—decreases of -28.7% on 2-Lane/2-Way Highways; -28.7% on 4-Lane Divided Highways; -42.9% on Rural Freeways; and -11.2% mph on Urban Freeways. The University’s evaluation also showed there were reductions in the numbers of fatal and life-changing crashes during the MSMP. MarketLine Research conducted the second evaluation, using telephone surveys, and found nine in ten drivers support the speed limit increase from 55 mph to 60 mph in both Metro and Greater Minnesota. The MSMP, in concert with other efforts that are part of the Minnesota Comprehensive Highway Safety Plan, resulted in reductions in the number of speeders on Minnesota Highways and reductions in the number of fatal and lifechanging crashes—making Minnesota’s roads safer.

A fully interactive PC-based STISIM driving simulator was used to test the effectiveness of Intelligent Lane Control Signals (ILCS). These ILCSs presented (1) 45-mph speed limit messages; (2) 35-mph speed limit messages; (3) a yellow lane closure warning; (4) one of three merge messages that used a diagonal arrow, or words, or dynamic chevrons to indicate that drivers should move from the center lane; (5) a red lane closure warning. Analysis of lane position data showed that the diagonal arrow merge sign was the most effective. Analysis of driving speed data indicated that the speed limit signs were effective.

A fully interactive PC-based STISIM driving simulator compared dual-phase Changeable Message Signs (CMSs) and static CMSs. The participants were 120 licensed drivers from three age groups: 18-24, 32-47, and 55- 65 years of age. They drove eleven miles on a simulated six-lane highway towards an airport, knowing which airline to look for. Airline information was provided on two separate CMSs located 500 ft (152.4 m) apart on the highway in one condition, or on a single dual-phase CMS in the other condition. The participants took the correct exit on 89.6% of the drives (215 of 240). There were no statistically significant differences between the number of participants who failed to take the correct exit in the dual-phase and the static CMS conditions. On the approach to the CMSs displaying airline information, there were significant differences in average speed between the three age groups-younger drivers drove faster than middle age and older drivers. However, average speeds were not different in the dual-phase and static CMS conditions. Some individuals reduced speed on approaching the CMSs-suggesting similar reductions could occur in real world driving in free flow conditions. There were no differences in the number or magnitude of the speed reductions for the dual-phase and static CMS conditions. In this experiment, displaying airline information on a single dual-phase CMS was as effective in influencing driving behavior as displaying the same airline information on two static CMSs.

This report describes Phase II of an investigation into the effectiveness and safety of traffic-related messages presented on changeable message sign (CMS) displays. In this phase of the study, two target-message experiments directly comparable to the Phase I experiments were shown to three groups of drivers, who had been separated by age, while they were driving a P-C based STISIM driving simulator. The researchers also collected real-life data from I-35W and 73rd Street when CMS messages were deployed and visited Mn/DOT's Regional Transportation Management Center. The results of this research showed that clarifying and reducing the complexity of CMS messages was beneficial.

This report, an evaluation of the Minnesota Speed Management Program, concludes that the program has resulted in a reduction of the number of speeders as well as the number of fatal and life-changing injuries on Minnesota highways. The report recommends the program be continued with an evaluation element added.

This was the third in a series of studies investigating various aspects of rumble strips. In this study, to determine the effect of rumble strips on the real-world stopping behavior of drivers, we used a radar gun to collect speed data from over 400 vehicles on the approaches to ten intersections selected from a sample of 274 approaches. We found that, after drivers encountered the first set of in-lane rumble strips, they slowed down earlier on real-world approaches With Rumble Strips than on real-world approaches Without Rumble Strips-the difference was, on average, 2.0 mph to 5.0 mph (depending on vehicle category and type of approach). In addition, speeding outliers were more likely to slow down earlier on approaches With Rumble Strips. The effect of the presence of in-lane rumble strips on stopping behavior was greater for approaches where the driver's view of traffic on the major road is obscured on one or both sides of the road. The study suggests that stop-controlled intersections at which cross-traffic is obscured by manmade structures and/or vegetation on one or both sides of the intersection would be good candidates for implementing in-lane rumble strips. It is worth noting that while in-lane rumble strips are likely to reduce crashes, they cannot eliminate them. Some drivers might still run stop signs and others might misjudge gaps.

Drivers receive value from traveler information in several ways, including the ability to save time, but perhaps more importantly, from certainty, which has other personal, social, safety, or psychological impacts. This project aims to quantify travelers' willingness to pay for pre-trip travel-time information on alternative routes. Different from previous studies based only on stated preference surveys, the 117 participants in the current study actually drove real-world routes. Pre-trip travel-time information was provided in the field experiment to half the participants. Various data collection techniques were used including in-vehicle GPS units, pre- and post-experiment surveys, and travel diary. Results reveal that speed and efficiency are not the only dimensions on which people make route choices. Ease of driving, pleasantness, and the presence of information are also significant factors. Results from multinomial and rank-ordered logit models indicate that many travelers receive value of up to $1 per trip for pre-trip travel-time information. The value of this information is higher for commuting, special event trips, and when there is heavy congestion. The accuracy of the travel-time information is crucial - it is only useful if it is believed to be accurate.

This study is the second in a series investigating rumble strips. The objective was to determine the effect of rumble strips on the stopping performance of sleep-deprived drivers. [The study was nested in a larger fatigue study with components unrelated to rumble strips.] The participants were 20 commercial motor vehicle drivers. Each participant was tested over a twenty- hour period, driving in a driving simulator for one hour in the morning, afternoon, evening and at night. During each drive, the participants encountered two stop-controlled intersections-one with rumble strips and the other without rumble strips. The braking pattern of the drivers was affected by the presence of rumble strips- from the appearance of the first set of rumble strips [218 meters (715.2 ft) from the intersection] until the drivers stopped at the intersection. The mean speed of drivers approaching the intersection with the rumble strips was statistically significantly slower than the mean speed for drivers approaching the intersection without the rumble strips. Though sleep deprivation did not affect the driver's braking patterns on the approach to the intersections, it did affect steering variability throughout the course of the drive.

The objectives of this study investigating Changeable Message Signs (CMS) were to determine whether or not CMS messages really work, whether or not they cause traffic slow downs, and whether or not they have an impact on traffic flow. The participants were 120 licensed drivers from three age groups--18-24, 32-47, and 55-65 years old.