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Flaggers protect workers by providing temporary traffic control and maintaining traffic flow through a work zone. They are often the first line of defense to stop distracted, inattentive, or aggressive motorists from intruding into the work area. This project aims to develop an automated intrusion detection system to alert drivers who are unsafely approaching or entering a flagger-controlled work zone. A human factors user needs assessment found maintenance workers preferred a modified traffic signal to feature the alert system due to flagger risks of being in the roadway and drivers failing to stop and remain stopped when presented with the STOP side of the flagger sign. A modified traffic signal that could be operated using a handheld remote was developed. The low-cost embedded electronics on the traffic signal enabled it to track trajectories of nearby vehicles, detect potential intrusions, and trigger audio-visual warnings to alert the intruding driver. Usability testing in a simulated driving test found poor expectancies and stopping rates of the traffic signal-based alarm system compared to a traditional flagger but did demonstrate evidence that drivers may be less likely to stop and remain stopped with the flagger STOP sign than the red ball indicator of the traffic signal. Furthermore, some drivers corrected their initial stopping error after triggering the auditory alarm of the traffic signal. A follow up test found improved performance with the alert system incorporated into an audiovisual enhanced STOP/SLOW flagger paddle. Testing of the developed sensor system found the system capable of simultaneous multi-vehicle tracking (including estimation of vehicle position, velocity, and heading) with a range of up to 60 meters and angular azimuth range of 120 degrees and correctly detecting all test intruding vehicles.

The Minnesota Department of Transportation (Mn/DOT) has concluded that at certain high speed locations, providing additional information to the motorist describing the operation of the traffic signal can assist the driver in making safer and more efficient driving decisions. The additional information includes a visual indication to get the driver's attention and a specific notice that the driver must prepare to stop. The Advance Warning Flasher (AWF) is a device which Mn/DOT uses to convey this information to the driver. The Mn/DOT A WF system consists of a flasher and a sign located on main street approaches to a high speed signalized intersection. The AWF is connected to the traffic signal in such a way that when the main street green is about to change to yellow, the flasher is turned on to warn the approaching drivers of the impending change. Basically, the purpose of an optimally designed combination of traffic signal and AWF system is twofold: 1) to inform the driver in advance of a required driver decision (prepare to stop) and 2) to minimize the number of drivers that will be required to make that decision. Over time, questions have arisen regarding the use and application of AWF devices. The purpose of this study was to examine the effectiveness of the current AWF operation and, where possible, to make recommendations to improve it. The study concluded that the use of AWF devices can be effective at reducing right angle and rear end accidents under certain situations but that the device does not automatically increase the safety of all intersections. Accordingly the device should be considered as a traffic engineering tool to be used to correct situations of special need. Further, this study developed a scheme to optimize AWF operation. The proposed approach will theoretically produce an optimized A WF location/operations scheme but must be field validated as part of a suitable test study.

This document discusses photovoltaic products which make use of solar energy to power highway signs and signal lights in remote areas. Included are the location of some of these products, their effectiveness, costs associated with their use, transportability, and appropriate uses. Also included is a review of the experiences Hennepin County has had with solar energy.

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.

This work reports results of an experimental program on human factors issues in traffic signing. The first task examines the problems associated with the programming of signs for evaluation of driver response in simulation. It is concluded that growing technical tools permit traffic engineers to test proposed signage, and avenues of implementation are given. The second task examines driver response in simulation to multiple real-world signs. It is concluded that while much effort is given to distinguishing the utility of individual signs, multiple signs in combination produce more complex decrements. Recommendations are made as to maximum sign density. The final task provides an assessment of signage in future IVHS driving environments. It points to the role of signage as one component of communication. A list of issues for future signage implementation is given for consideration as the Department moves to provide safe and efficient transport for the people of Minnesota into the 21st century.

To improve the visibility and safety of pedestrian and bicyclist crossings, traffic-safety professionals across Minnesota have installed the Rectangular Rapid Flashing Beacon (RRFB) and Pedestrian Hybrid Beacon (PHB) at numerous locations around the state. The purpose of this evaluation was to determine the safety benefits, if any, for pedestrians and bicyclists after installation of an RRFB or PHB. This report included a before-after analysis as well as a cross-sectional analysis for each type of beacon with a corresponding group of comparison sites. The before-after analysis found that installation of an RRFB resulted in a 67% decrease in fatal crashes and a 62% decrease in bicyclist crashes. Installation of a PHB resulted in a 53% decrease in suspected minor injury crashes, a 67% decrease in pedestrians crashes, and a 50% decrease in bicyclist crashes. The results of the cross-sectional analysis did not indicate that these reductions were statistically significant compared to similar reductions in the control group. Still, the decreases in severe crashes and crashes involving non-motorists at RRFBs and PHBs indicated that both types of beacons could be effective safety treatments.

This research evaluates the performance of non-intrusive detection technologies (NITs) for traffic signals in Minnesota. Prior work shows that while no single NIT device performs best in all situations, under specific circumstances, some NIT devices consistently outperform others. Our goal in this research is to find which NIT devices perform better in conditions specific to Minnesota and provide cost estimations and maintenance recommendations for operating these devices year-round. Our research has two main components: 1)synthesizing national and local experiences procuring, deploying, and maintaining NITs, and 2) evaluating real-world NIT deployments in Minnesota across different weather conditions. Our results and analysis combine the results from these steps to make recommendations informed by research and real-world experience operating NIT devices. Through interviews with Minnesota traffic signal operators, the research finds that environmental factors like wind, snow, and rain cause most NIT failures, requiring costly on-site maintenance. Operators emphasize the need for central monitoring systems, sun shields, and heated lenses to maintain performance. The research then analyzes NIT video, signal actuation, and weather data at six Twin Cities intersections using Iteris and Autoscope Vision technologies. No single NIT performs best, aligning with previous findings, but Autoscope Vision is less prone to lens blockages requiring on-site service. Our analysis also finds some intersections have more failures, indicating location and geometry impact performance. Key recommendations are based on the relative performance of a NIT in different weather conditions and accounting for local weather conditions when selecting a NIT at an intersection. We also recommend using central monitoring systems to troubleshoot remotely, installing heat shields to prevent snow/rain accumulation, and routine annual checks and checks after major storms.

This report summarizes the findings of a human factors analysis to determine the effects of advanced warning flashers (AWFs) on simulated driving performance. The Minnesota Department of Transportation sponsored the project. Researchers used the flat-screen simulator at the University of Minnesota Human Factors Research Laboratory to conduct experiments. They measured vehicle speed, braking, and acceleration/deceleration during simulated driving and visually observed stopping behavior. In addition, they analyzed responses to a post-test questionnaire. They created a 11.3-mile simulated driving environment with 10 signalized intersections and configured four experimental models: low speed limit (SL) of 50 miles per hour with no AWFs, low SL with AWF at each intersection, high SL of 65 miles per hour with no AWFs, and high SL with AWF at each intersection. Researchers set different vehicle-signal proximity intervals, with all green/ no yellow as the control, and zero seconds with the vehicle adjacent to the signal, two seconds, three-and-a-half seconds, or five seconds. With each model, they assigned two intersections each proximity interval, with the sequence of intersection proximity intervals ordered differently for each model. Each of 24 subjects completed duplicate driving trials with each model. The study revealed that, relative to intersections with no AWFs, drivers who encountered yellow signals at AWFs intersections: stopped more frequently at low SLs but not at high SLs, drove more slowly while approaching intersections with two and three-and-a-half second proximity intervals, and displayed less inconsistent behavior at intersections with short proximity intervals. Researchers concluded that AWFs assist drivers with decision-making behavior and promote safer driving behavior. They recommended field research to study and actual environment.

This research project evaluated the effectiveness of speed reduction techniques in high pedestrian areas and provided traffic speed data to facilitate the validation of a traffic calming study at the University of Minnesota's Human Factors Research Laboratory. Researchers collected speed data at four selected study sites under existing conditions and at two sites, in Twin Lakes and Bemidji Lake, both under existing conditions and after the installation of proposed speed reduction strategies. The strategies at the Twin Lakes site consisted of removable pedestrian islands and pedestrian crossing signs. At Bemidji Lake, a dynamic variable message sign was installed. The research study shows that the traffic calming strategy at Twin Lakes effectively reduced the mean speed and improved speed limit compliance in both the short and long term. Despite proven effectiveness, the deployed speed reduction treatment in Bemidji Lake failed to lower the speed at the study site.

This study examined the operation of static and dynamic no right turn on red (NRTOR) signs at eight signalized intersections in Minnesota (six dynamic and two static). Driver compliance with the NRTOR indications were measured using video data. Most dynamic NRTOR sign locations were pedestrian-activated, with one location having additional time-of-day activation of the NRTOR indication. Compliance rates were calculated per signal cycle and per vehicle. Per-cycle compliance rates were 60.8% for dynamic and 80.0% for static sign locations, while per-vehicle compliance rates were 87.1% for dynamic and 92.4% for static sign locations. Statistical models were further developed to confirm the statistical significance of the results and to explore the strength of the effect compared to other intersection characteristics. A survey of practitioners was included to identify the installation and maintenance costs of DNRTOR devices. The report concludes with recommendations on uses of DNRTOR.