PDF

This report presents algorithms for vision-based detection and classification of vehicles in monocular image sequences of traffic scenes recorded by a stationary camera. Processing occurs at three levels: raw images, blob level, and vehicle level. Vehicles are modeled as rectangular patches with certain dynamic behavior. The proposed method is based on the establishment of correspondences among blobs and vehicles, as the vehicles move through the image sequence. The system can classify vehicles into two categories, trucks and non-trucks, based on the dimensions of the vehicles. In addition to the category of each vehicle, the system calculates the velocities of the vehicles and generates counts of vehicles in each lane over a user-specified time interval, the total count of each type of vehicle, and the average velocity of each lane during this interval.

This report summarizes an experimental program that investigated the development length and variability in bond of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete.

This research project investigated the effects of pre-release cracks on girder camber, flexural cracking capacity, and steel stress ranges. The research included a parametric study investigating stress ranges in the prestressing strands in uncracked, cracked and partially cracked girder sections to determine if steel fatigue was a concern. An analytical study also was performed, which modeled several pre-release cracks, including models of two experimental girders that developed pre-release cracks, to determine the effect of various cracks on girder stress and camber. The study concluded that steel fatigue in the prestressing strand is a concern in girders that become cracked in service. A loss of compressive stress is believed to occur in the bottom fiber of the girder because of pre-release cracks, which may result in the section cracking at lower applied load. Finite element modeling determined the loss of compressive stress in bottom fiber of girders with pre-release cracks. Analytical models also showed that pre-release cracks remained local to the crack location, that non-linear stress distributions occurred during the process of crack closure, and that the magnitude of the pre-release crack effects depended on the number of cracks, the crack width, and the crack depth.

In this project, researchers investigated methods for mitigating corrosion in reinforced concrete structures on the substructure of a bridge in Minneapolis, Minnesota. They treated several corrosion-damaged columns and pier caps with electrochemical chloride extraction (ECE). Then selected ECE-treated and untreated structures were wrapped with fiber reinforced polymer (FRP) wraps or sealed with concrete sealers to prevent future chloride ingression. They installed embeddable corrosion monitoring instrumentation in the field structures to evaluate the effectiveness of ECE treatment. Although the ECE process reduced average chloride levels in the treated structures by approximately 50%, several locations still had chloride concentrations in excess of the established corrosion threshold following ECE treatment. Resistivity probe failures that occurred at some of these locations indicated corrosion within the treated structures still could occur, despite re-passivation of the reinforcing steel following ECE treatment. Continued monitoring of the installed instrumentation is required to evaluate the long-term effectiveness of ECE treatment and concrete wrapping/sealing as a corrosion mitigation technique. In laboratory testing of the three FRP wrap types, the Mbrace CFRP and GFRP reported higher peeling loads and lower diffusion rates than the AMOCO CRFP, and thus were considered more effective sealant systems. However, concrete sealers are recommended to prevent future chloride ion ingress, instead of FRP wraps, because the use of sealers does not prevent visual inspection of the concrete for corrosion damage.

The situation of growing demand, and level or dwindling supply for civil engineering positions poses a significant challenge for Minnesota and for the country at large. To avoid turning the pending reality into a major crisis, though, Minnesota decided to take action. The Research Implementation Committee of Minnesota's Local Road Research Board sponsored the Minnesota Summit on Civil Engineering Workforce Development to address civil engineering employment issues. Held August 9, 2000, the summit attracted 44 leaders from the private and public sector, including representatives from city and county government, the Minnesota Department of Transportation, federal government, private engineering firms, industry and organizations, and educational institutions. Summit participants focused on the following tasks: Reviewing recent research on the expected demand and supply of civil engineers, surveyors, and technicians; Showcasing innovative methods of recruiting and retaining civil engineers, surveyors, and technicians by reviewing nationwide best practices; Examining the survey of cities, counties, and industry that assessed the nature of the problem in Minnesota; Developing an action plan that collaboratively leverages the resources of all the workforce development stakeholders; and Defining roles and responsibilities for solving the program among all stakeholders. Divided into four smaller groups, participants completed problem and vision statements for four key areas; awareness, attraction, access; recruiting; retention and redesign; and re-recruiting. The report details work completed at the summit and the actions that resulted from the summit.

This study presents statistically reliable conclusions based on a comparison of the operational and safety characteristics of rural intersections without turning lanes, with bypass lanes, and with left turn lanes. The basic work tasks associated with the research study included: a literature search of nationally published research reports, a survey of bypass lane use, a summary of the legal issues associated with passing on the right, operations and safety analyses, and a review of Minnesota Department of Transportation (Mn/DOT) recommended design guidelines and design features. The results of the safety and operations analyses did not offer a high degree of statistical reliability. However, a comparative crash analysis and a before-versus-after analysis suggested that it is impossible to conclude that the use of a bypass lane provides a greater degree of safety, and, therefore, bypass lanes should not be used as a safety device. There also were some concerns expressed about safety issues at four-legged intersections. Recommendations included: Revise Mn/DOT turn lane policies to at least reduce or eliminate the use of bypass lanes at four-legged intersections; Consider developing a shorter and less costly exclusive left turn lane design; and Offer designers positive guidance regarding the use of left-turn lanes, through a prioritized approach based on the functional classification of the major roadway.

This research report summarizes the results of a project to assist in the development of a mix design procedure for partial depth cold in-place recycling (CIR) mixtures. An asphalt pavement rehabilitation method, CIR involves mixing reclaimed asphalt pavement (RAP), water, and a recycling agent in place and without heat. During the construction of partial depth cold in-place recycling, one type of CIR, milling is done at depths of 50 to 100 mm (2 to 4 in.) with the resulting layer frequently used as base course. In this project, researchers mixed RAP from Trunk Highways 23, 59, and 71, and County State Aid Highway 5 with emulsions CSS-1, HFMS-2s, and HRMS-2p. After preparing specimens with a gyratory compactor and Marshall hammers, researchers tested the specimens for bulk specific gravity, maximum specific gravity, and air voids. In addition, indirect tensile strength tests were used to evaluate the effects of changes in curing periods and compactive effort on CIR mixtures. Researchers concluded that the asphalt content in the RAP affects the emulsion to be added in the CIR mixture; that emulsion HFMS-2p resulted in the lowest overall voids; and that the gyratory compactor produced the best specimens for testing and evaluation.

This report 1) describes the potential for improving bicycle transportation in the Twin Cities metropolitan area, 2) identifies the common barriers and limitations to bike transportation as described by metro area transportation officials and bicycle advocates, and 3) provides an overview of the organizations involved. The cities of Boulder, Colorado; Madison, Wisconsin; and Toronto, Ontario, Canada have built reputations for being bicycle friendly and were reviewed to provide examples of innovative bicycle programs. This guide serves as a starting point in describing bicycle transportation in the Twin Cities metropolitan area. Management of the transportation system in the Twin Cities metropolitan area is based on a multi-agency, regional approach. The Metropolitan Council, the Minnesota Department of Transportation, the counties and the cities all have responsibilities related to transportation in their jurisdictions. Important areas for development in order to make bicycling a viable transportation choice include: bike facilities, leadership, communication, planning, networks, research, measurement, partnerships, funding, information sharing, and customer needs.

Maintaining roadsides for safety and aesthetics is an important issue for all levels of government throughout Minnesota. Vegetation is one important element of roadside maintenance. This handbook provides guidelines for effective management of roadside vegetation for local agencies, and highlights seven best management practices that were identified through research, surveys, and discussion with industry experts. The seven best management practices for roadside vegetation fall into these seven categories: 1. Develop an integrated roadside vegetation management plan; 2. Develop a public relations plan; 3. Develop a mowing policy and improved procedures; 4. Establish sustainable vegetation; 5. Control noxious weeds; 6. Manage living snow fences; 7. Use integrated construction and maintenance practices. The main conclusion from the handbook is that successful roadside vegetation management depends on an integrated approach. This includes a wide variety of best management practices to address the many issues involved. This integrated approach includes an assessment of the existing conditions and determination of the type of roadside environment desired. Other construction operations, including proper seeding techniques, selection of the correct plant in the right area, selection of salt-tolerant seed species where needed, and erosion control, will greatly affect the roadside condition. Use of integrated construction and maintenance practices is one of the most important best management practices identified in the handbook. An updated version is available in report 2008-20.

This project used research to develop more effective criteria for placement and removal of spring load restrictions (SLR). Researchers investigated a method that uses a thawing index equation based on air temperatures to predict thawing events. Results showed that adjusting the reference temperature improved the spring-thaw prediction for Minnesota. Researchers compared historical SLR posting dates from 1986 through 1998 to the dates predicted using this new technique and to falling weight deflectometer and in situ instrumentation readings from 15 flexible pavement test sections in Minnesota. According to results, there was typically a week or more delay from the time that SLR should have been placed until actual posting of restrictions, which caused damage that could have been prevented. Based on testing performed on pavement sections across the state, the typical period required for pavement base and subgrade layers to regain sufficient strength to support heavy truck loads was eight weeks. In 1999, the Minnesota Department of Transportation adopted the improved procedure for placing and removing SLR. The policy uses actual and forecasted average daily temperature to determine timing of SLR. When the SLR duration is fixed at eight weeks, it is easier to plan for the end of the restriction period. Researchers estimate an increase of 10% in a typical low-volume asphalt road's life with implementation of the improved SLR procedures, resulting in a potential savings of more than $10 million annually.