Hallmark, Shauna L.

As a low-cost countermeasure to rural intersection crashes, transverse rumble strips (TRS) provide an audible and tactile warning to drivers approaching an intersection with the primary goal of decreasing crashes that result from running a stop sign. The objective of this project is to evaluate the effectiveness of different TRS patterns on stopping behavior at rural stop-controlled intersections. Eight rural intersections in St. Louis County, Minnesota, were selected as test sites. Milled-in rumble strips were installed at the sites that varied in terms of number of panels (2 or 3) and number of rumble strips per panel (6 or 12). Speed, traffic volume, and video data were collected at each site before, 1 month after, and 9 months after TRS installation to evaluate various crash surrogate metrics. The most significant metrics affected by TRS configuration included percentage of vehicles engaging in a full/rolling stop at the intersection, change in average speeds on the approach near the intersection, percent of vehicles traveling 45 mph or more, and percent of vehicles engaging in late braking. A qualitative summary of the various metrics suggested that the 3-panel, 12-rumble strip design performed the best. Noise analyses were also conducted to assess whether the number of rumble strips per panel (6 or 12) affected exterior and in-vehicle noise. No significant differences in exterior noise were found, and both panels produced sufficient in-vehicle noise to alert a drowsy driver. As a result, noise was not a factor in selecting one panel type over another.

This study is a complement to Evaluation of Intersection Collision Warning Systems in Minnesota (2017-38), which was published in October 2017. That project evaluated behaviors such as type of stop for drivers on the minor approach in the presence of intersection collision warning systems (ICWS). This project was a follow-up to that study and compared speeds along the major street approaches at ICWS treatment sites after installation of the system to determine whether the ICWS provided any measurable impact on speed when drivers on the major street were presented with a message from the system (activated) versus when drivers were not presented with a message (not activated). The study found that mean and 85th percentile speeds were lower on the major approach when the ICWS was activated compared to when it was not activated. However, the differences were minor. As a result, the system is expected to reduce speeds, but only a modest impact is expected in terms of mainline drivers.

This report is one of the deliverables for the culmination of several phases of a project, which evaluated driver behavior in work zones using the SHRP2 Naturalistic Driving Study (NDS) data. This study utilized SHRP2 NDS to evaluate the impact of traffic control devices in reducing driver speed in work zones. The main advantage to the SHPR 2 NDS data is that on-road driver behavior was captured and can be used to evaluate how drivers behave in various situations. The study included four different analyses. The first evaluated where drivers began reacting to various work zone traffic control devices. The second assessed how drivers changed speed upstream to immediately downstream as they encountered various traffic control devices. The third assessed how drivers react when they encounter the back of a queue and the fourth developed speed based on work zone characteristics such as presence of barriers.

This toolbox is one of the deliverables for the culmination of several phases of a project, which evaluated driver behavior in work zones using the SHRP2 Naturalistic Driving Study (NDS) data. The toolbox summarizes information about work zone traffic control devices, countermeasures, and work zone features that have a demonstrated impact on speed in work zones. Features were identified through a survey of the literature. Additional information for some of the features and countermeasures was gained through the various analyses of SHRP2 data conducted through this project. Guidance from the work zone traffic control manuals for various states was summarized when appropriate. Recommendations for use of each feature or countermeasure relevant to addressing speed in work zones was developed by the team and reviewed by work zone experts and the project panel.

Reduced traffic volumes resulting from COVID-19, along with the strain on enforcement during the pandemic, are thought to have produced higher speeds and more aggressive driving. Understanding the magnitude of speeding and other driver behaviors requires measurement and contrast. This project quantifies reductions in volume and the resulting differences in travel speeds across Minnesota along regular roads and within two work zones prior to and during the novel COVID-19 pandemic. The work includes a review of total crashes as well as fatal and serious injury crashes and includes a survey of law enforcement opinions. Findings based on 125 Automatic Traffic Recorders (ATR) and traffic Sensors quantify volume reductions, which, of course, were lower in 2020 but which varied considerably by location and month. Average speeds overall along with both the number and percentage of vehicles traveling greater than 15 mph over the posted speed limit increased in 2020. This information supports benchmarking and agency decision making.

This toolbox was developed to provide a summary of information that local agencies should be aware of to prepare for connected and autonomous vehicles (CAVs). The main goal of this toolbox is to assist local agencies in preparing for CAVs in the short term--5 to 10 years. Since local agencies are not generally expected to have the resources to become test beds; this report provides information so that local agencies can leverage ongoing activities and resources to prepare for CAVs.

The Minnesota Department of Transportation (MnDOT) is investing significant resources in intersection collision warning systems (ICWS) based on early indications of effectiveness. However; the effectiveness is not well documented; and negative changes in driver behavior at treatment intersections may affect drivers overall; resulting in a spillover effect. Moreover; the effectiveness of ICWS may decrease if drivers do not perceive a change in the dynamic messages. Therefore; the objectives of this research were to (1) evaluate driver behavior at mainline and stop-controlled approaches for intersections with and without ICWS and (2) assess the traffic volume range and limits where the system is nearly continuously activated and is likely to lose its effectiveness. Video data were collected at five treatment and corresponding control intersections; and various metrics were used to compare changes in driver behavior. In general; no negative behaviors were noted for either treatment or control intersections.

The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a priority for national, state, and local roadway agencies. Horizontal curves are of particular interest because they have been correlated with increased crash occurrence. This toolbox was developed to assist agencies address crashes at rural curves. The main objective of this toolbox is to summarize the effectiveness of various known curve countermeasures. While education, enforcement, and policy countermeasures should also be considered, they were not included given the toolbox focuses on roadway-based countermeasures. Furthermore, the toolbox is geared toward rural two-lane curves. The research team identified countermeasures based on their own research, through a survey of the literature, and through discussions with other professionals. Coverage of curve countermeasures in this toolbox is not necessarily comprehensive. For each countermeasure covered, this toolbox includes the following information: description, application, effectiveness, advantages, and disadvantages.

This toolbox provides information to assist transportation agencies in utilizing roundabouts while evaluating traffic control at adjacent intersections, thereby avoiding adverse impacts on corridor performance. The information was developed by summarizing available information and conducting several evaluations. The toolbox addresses roundabouts as they relate to and/or impact the areas of comprehensive planning, mobility, unbalanced traffic flows, access management and other planning considerations.

INV 805: This study evaluated the effectiveness of street lighting on isolated rural intersections in reducing nighttime crashes, using both a comparative analysis and a before-and-after study, and found that street lighting can reduce the number of crashes.