Maintenance

This manual was created as part of Clear Roads project CR13-04,"Best Practices for the Prevention of Corrosion of Department of Transportation Equipment: A User’s Manual," Published April 2015.

This research brief was produced as part of Clear Roads project CR13-04, "Best Practices for the Prevention of Corrosion of Department of Transportation Equipment: A User’s Manual," published April 2015

This document is the final report for the Clear Roads project entitled Best Practices for the Prevention of Corrosion of Department of Transportation Equipment: A User’s Manual. The project team was led by researchers at the Western Transportation Institute at Montana State University (WTI) on behalf of Clear Roads, an ongoing pooled fund research effort focused on winter maintenance materials, equipment, and methods. Clear Roads research projects are managed and administered by the Minnesota Department of Transportation (MnDOT). Through this project, the research team developed a user-friendly manual that documents best practices for managing the risk of equipment corrosion, especially in the presence of chemical deicers. The audience for this manual includes operators, mechanics and garage-level supervisors. The manual defines the basic corrosion conditions, with a focus on the need for managing corrosion risks, common modes of corrosion failure, and corrosion-prone parts (priorities) on DOT equipment. This manual addresses design considerations and material selection for corrosion risk management. This manual also lists some commercial products that have been used by DOTs, and presents some successful experiences of DOTs, the US Navy and private companies. It also presents preventive maintenance strategies and tactics.

This Technical Summary pertains to Report 2023-04, “Development of a Mobile App for Reporting Work Zone Intrusions,” published January 2024.

Work zone intrusions represent a significant safety risk to workers. To help better understand these situations, the Minnesota Department of Transportation partnered with the University of Minnesota to create a method to document intrusion events. This information provides a deeper understanding of the circumstances under which these events occur and enables data-driven decision making when considering ways to reduce or mitigate work zone intrusions. This work focuses on the development of a mobile smartphone app that allows workers to report intrusions from the field immediately after they occur, allowing for timely and accurate intrusion reporting. The work zone intrusion mobile app is developed using an iterative, user-centered design process that solicits feedback from work zone personnel, supervisors, and work zone safety stakeholders at every step in the process. The app uploads completed report data to the existing eSAFE system, allowing for a single repository of collected intrusion report data. To support deployment of the system, training workshops and supporting training and communications materials are created for distribution among users. Throughout the development and deployment of the app, user feedback shows that the app is easy to use and well liked.

Many state, county, and municipal highway agencies have experienced the formation of bumps when placing single-lift overlays or the first lift of a multiple lift overlay. These bumps are produced at the location of a previously-existing crack, and even then almost exclusively when the crack has been sealed prior to the overlay. When such bumps are not covered with a subsequent lift, what remains is often a rough ride on a newly-overlaid roadway. This paper describes the effects of crack sealant material type and the geometry (shape) of the routed cracks in the existing surface on the formation of bumps in bituminous overlays. A matrix of four sealant type treatments and six geometries was designed, and implemented in a test section in Jackson County, Minnesota. The overlay on the test section was constructed in September 2007. The results of this investigation indicate that cooler pavement surface temperatures, no overband, hot-poured crumb rubber and hot-poured elastic sealants provided the best resistance to the formation of bumps in overlays. Content Note: This is the author’s version of a work that was accepted for publication in the Transportation Research Record: Journal of the Transportation Research Board, Issue Number: 2108, Publisher: Transportation Research Board ISSN: 0361-1981. The final version can be found at https://doi.org/10.3141/2108-08.

There has been a sustained effort in applying fracture mechanics concepts to crack formation and propagation in bituminous pavement materials. Adequate fracture resistance is an essential requirement for asphalt pavements built in the northern part of the US and Canada for which the prevailing failure mode is cracking due to low-temperature shrinkage stresses. The current Superpave specifications address this issue mainly through the use of strength tests on unnotched (smooth boundary) specimens. However, recent studies have shown the limitations of this approach and have suggested that fracture mechanics concepts, based on tests performed on notched samples, should be employed instead. Research in progress at University of Minnesota investigates the use of fracture mechanics principles to determine the low-temperature fracture properties of asphalt mixtures. This paper presents a testing protocol that allows obtaining multiple measurements of fracture toughness as a function of crack propagation based on the compliance method to measure crack length. An increase in fracture toughness with crack length is observed, which is consistent with the behavior displayed by other brittle materials. The plateau of the curves may be representative of the asphalt concrete resistance to fracture because the initial values can be significantly influenced by the presence of the inelastic zone at the crack tip. Content Note: This is the author’s version of a work that was accepted for publication in the Transportation Research Record: Journal of the Transportation Research Board, Issue Number: 1789, Publisher: Transportation Research Board ISSN: 0361-1981. The final version can be found at https://doi.org/10.3141/1789-21.

A vertical-lift bridge, the Stillwater Bridge, Bridge 4654, opened in 1931 across the St. Croix River between Minnesota and Wisconsin. To assess the remaining fatigue life of this bridge, strain gages were installed on an interior floorbeam and on a tension chord of a typical through truss span. The maximum stress range was 32 MPa at the centerline of the floorbeam. The measured data were rationalized by performing an analysis of the floor system and truss. The greatest ratio of the maximum expected stress range (18 MPa) to the fatigue strength (31 MPa) is at the centerline of the severely floorbeams located at the ends of the spans. Therefore, fatigue cracking is not expected in the steel members of a typical truss and taking the trucks off the bridge will have no significant effect on the fatigue life of the steel members in a typical through truss span. As a staff paper, this publication is intended for internal use by the Minnesota Department of Transportation (Mn/DOT). Distribution is limited

During the fall of 1969 transverse cracks were sealed in a 13-mile section of bituminous pavement. Five hot-poured rubber asphalt sealers, three tack coat materials for priming the crack sidewall, a bond breaker and 40 different application procedures were used. Test sections were established to evaluate the materials and procedures. Field surveys were conducted to determine the amount of footage failed. Reference pins were also installed to measure crack movement. The field results were used to evaluate the materials and procedures incorporated in the study program.

The purpose of the the study presented in this report has been to develop relationships useful for predicting the service life of existing flexible pavements and extension of service life which can be expected after the pavement has been maintained. The concepts and results from Minnesota Investigation 183 are used for this study. Investigation 183 is a study started in 1963 for which the performance of 50 in-service test sections has been observed up until the present time. The performance has been defined as some function of the decrease in a numerical condition rating of the pavement with time or with accumulation of traffic. The numerical condition rating used is the Present Serviceability Index which defines the condition of rideability on a scale from 0 to 5. A value of 2.5 has been considered a reasonable level at which a pavement should be maintained. Generally, a higher level may be more appropriate for higher traffic roads and a lower level for lower traffic roads. The present serviceability concept was originally developed at the AASHO Road Test and the ratings on the Minnesota test sections have been obtained using an equation developed for prediction of this value with the Minnesota roughometer.