Hawkins, Neal

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.

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.

Pavement marking is important for safety. Maximizing pavement marking performance in terms of increased retroreflectivity; within limited budget constraints; allows agencies to make better decisions toward providing more effective pavement marking performance on their roadway networks. This research project included conducting a survey of local agencies' pavement marking practices; mining existing National Transportation Product Evaluation Program (NTPEP) pavement marking data; and developing recommendations for future pavement marking research to support local agency needs. The NTPEP pavement marking performance data (related to pavement marking products used by local agencies in Minnesota) was analyzed to provide guidance to local agencies in terms of pavement marking material selection based on performance. The objective included determining pavement marking products of interest to local agencies and developing performance metrics for these products based on existing NTPEP data. The analysis performed on the NTPEP included modeling the deterioration behavior as a function of time. Also two-way ANOVAs were performed to compare various performance measures and the impact of different conditions on these measures.

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.

This research effort provided the Minnesota Department of Transportation (MnDOT) with field data on the performance of pavement marking materials when used as rumble stripes on MnDOT roadways. These field efforts provide a perspective on the impact that both wear and winter maintenance practices have on retroreflectivity. Given that these markings were installed by a variety of MnDOT contractors and at different times and roadways, this report also serves to document the range of retroreflectivity provided to drivers at any given time on similar two-lane MnDOT roadways under the installation practice guidelines at the time of installation (2012 to 2013). More specifically, these measurements consider the difference in retroreflectivity provided by direction of travel (e.g., for the same marking, what is the retroreflectivity while driving northbound versus southbound?) and by roadway. The long-term evaluation collected field measurements both initially and after two winters (18 months) for centerline rumble stripes only and on seven segments over three different roadways. The in-service evaluation included new centerline and profile rumble stripEs, all of which were installed as part of the 2013 mill and overlay projects on bituminous surfaces within District 4 on two-lane MnDOT roadways. The retroreflectivity data were collected one winter (approximately 12 months) after installation with no initial measurement data being available. This effort included measuring the centerline rumble stripe performance over eight segments on four different roadways and the profile rumble stripe performance over 18 segments on 10 different roadways.

The objective of this research was to conduct a field trial to evaluate the marking performance of different combinations of pavement marking materials and installation practices on challenging surfaces. The trial included a range of pavement marking products over varied roadway characteristics to assess the performance of different marking materials over different challenging surfaces by product, thickness, bead package, and whether or not a primer was applied. The research team worked with the technical advisory panel (TAP) to document pavement marking performance on several municipal roadways within the city of Eden Prairie and to organize and prepare for field testing of different marking materials on both a seal coat and micro surface roadway. These projects provide pavement marking performance on challenging surfaces information over different conditions (traffic levels and line types) apart from the MnDOT research test deck scenarios. These results provide MnDOT with a basis to consider pavement marking striping practices on challenging surfaces in terms of performance and cost. The high-build materials (primer plus VISILOK) and epoxies showed similar performance, which provides a good basis for material selection.

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.

The objective of this project was to fully implement the Pavement Marking Management Tool by incorporating retroreflectivity and striping data (MnDOT and contractors) and simplifying the process of data collection, storage, and analysis. As part of achieving full implementation, the researchers provided training to MnDOT central office staff and staff in each of the districts. Improved pavement marking management has the potential to reduce MnDOT's costs, improve pavement marking performance, and in return provide a more efficient and safe driving experience for the traveling public. The result of this effort included a web-portal for submitting pavement marking data (paint and retroreflectivity), a geographic information system (GIS) web based tool to manage, view, and create reports on pavement marking data, and training on the data collection and tool. This technical memorandum presents project findings by task.

Minnesota Department of Transportation (MnDOT) staff has experienced that pavement markings do not perform well on seal coat and micro surface treated roadways, referred to as "challenging surfaces." This report serves as a beginning point and organized approach in addressing pavement marking practices on challenging surface roadways. The project objective was to document existing district practices and issues through several key tasks, which include a literature review, field review, and analysis of existing practice and performance. This effort identified the need for a field trial to provide control in the evaluation of these markings on challenging surfaces. An outline was developed for a future field trial effort, which will evaluate the marking performance of different combinations of pavement marking materials and installation practices. These project findings will be used in conjunction with the resulting field trial evaluations to improve MnDOT guidance and standard practice that will result in better performance, efficiencies, and roadway safety.

Pavement marking is an essential component of roadway construction and safety. The markings need to be visible (day and night) so that drivers can quickly identify where the markings are and determine what message is being defined. Good pavement marking provides critical elements to guide drivers on correct road paths, complement road signs that inform and warn drivers, and improve night driving conditions. This project's objective was to review existing pavement marking practices by local agencies in Minnesota (material selection, installation, specifications, and contracting procedures) to provide guidance for maintaining good pavement markings, thereby saving money and increasing road safety. The two specific objectives were as follows: 1. Review existing pavement marking practices in local agencies. 2. Develop recommendations for better management of pavement marking through the use of pavement marking management tools and coordination with the Minnesota Department of Transportation (Mn/DOT).