Research Reports

The Minnesota Department of Transportation (Mn/DOT), contracted with Donohue and Associates, Inc. of Sheboygan, Wisconsin to survey five bridge decks and approximately 79 lane miles of continuously reinforced concrete pavement (CRCP) and asphalt-overlaid jointed reinforced concrete pavement in Minnesota. All of the work was in the St. Paul-Minneapolis metropolitan area except for two bridge decks, located in Moose Lake and Cloquet. Several test sections were also surveyed with Mn/DOT's Delamtect for purposes of comparing the results produced by the two techniques.

This report documents the activities and results of a 2-year test of non-intrusive traffic detection technologies. Non-intrusive technologies are defined as data collection methods that can be done without intruding into the roadway for installation. Non-intrusive devices have the advantage of not disrupting traffic flow or exposing field personnel to dangerous conditions. While there is potential for new technologies to replace the traditional methods of data collection, such as inductive loop detectors and road tubes, there are many questions regarding their performance. This report provides practitioners with useful information about the performance of non-intrusive technologies and specific devices within each technology. Seventeen devices representing eight different technologies were evaluated in varying environmental and traffic conditions. The following technologies were tested: passive infrared, active infrared, magnetic, radar, doppler microwave, pulse ultrasonic, passive acoustic, and video. Testing was done at both freeway and intersection locations. Emphasis was placed on urban traffic conditions, such as heavy congestion, and locations that typify temporary counting locations, such as 48-hour or peak hour counts. The evaluation also focused on the ease of system setup and use, general system reliability, and system flexibility.

This report is intended as a resource document for use by transportation analysts in comparing the energy intensities of various transportation alternatives. "Energy intensity" is defined as the energy use per unit of productive output. Transportation accounts for a significant portion of the total energy consumption in the United States, utilizing over 25 percent of the annual total. Consequently, the energy impacts of transportation alternatives are a critical national concern. Any reduction in energy consumption which can be realized in the transportation sector will contribute substantially toward the alleviation of the U.S. energy problem.

In 1980, Minnesota passed a new law for controlling overweight trucks. This new law allowed bills of lading, weight tickets, and other documents that indicate the weight of a truck to be used as evidence in a civil court proceeding to establish overweight violations. Under many circumstances it is no longer necessary for the State Patrol to catch an overweight truck on the road. A demand for the payment of penalties can be sent out in the mail and if not paid, a civil law suit will be initiated by the state. "Relevant evidence" of such weight documents is now used by the civil weight enforcement group of the Department of Public Safety and is proving to be an excellent addition in the restriction of illegally overweight motor carriage. This report discusses the history of Minnesota weight enforcement and the role of the relevant evidence law in constructing a comprehensive weight enforcement system.

This report presents the results of a review of long held contentions regarding driver choice of speed and reaction to speed limits. Areas of concern that were studied included influence of the roadway environment, reaction to school speed zones and reaction to warning flashers. Results of the review show that drivers do vary their speed under differing conditions, they do not react as desired to lowered speed limits or to passive signing. They do lower speeds when they see a warning flasher in conjunction with limit signs, but not as much as is requested. There was evidence too that in some zones a lower limit may result In a more hazardous situation.

A Minnesota retrofit W-beam guardrail to concrete safety-shaped (Type J) bridge rail transition design with a separate end post was previously crash tested and found to have unsatisfactory impact performance. The design was improved with the addition of a channel rub rail and the improved design was crash tested and evaluated in this study. In accordance with guidelines outlined in NCHRP Report 230, one crash test was conducted on this improved transition design. Results of the crash test indicated that this improved design met all impact performance evaluation criteria as outlined in NCHRP Report 230. This improved transition design is recommended for approval in field applications.

New bridge decks will be designed to standards which insure a reasonably long maintenance free life. The new bridges have been grouped into three categories with a deck protective system designed to be cost effective for the anticipated exposure to de-icing chemicals in each of these categories.

A task force composed of personnel from the Offices of Bridges and Structures, Materials, Research and Standards has reviewed and analyzed existing procedures for protection of bridge decks. The objectives of the task force were: 1. To develop policy for installation of protective systems on new bridge decks. 2. To develop policy for establishing priorities and selecting methods for contract restoration and protection of in-service bridge decks. 3. To develop policy for systematic maintenance utilizing M.H.D. forces, for the preservation of in-service bridge decks which are not being considered for contract restoration. The objectives were set to protect the bridge deck investment in a cost-effective manner and within budget limitations.

This study was initiated to investigate the possible causes for excessive lamp failure rates on High Mast illumination towers in the State of Minnesota. This type of highway illumination system consists of high masts on which there are either three or four luminaires. The masts are 120 feet (36.6 meters) high and the luminaries are attached to a ring assembly that can be lowered for lamp replacement. The study consisted of two methods of analysis. The first step was to analyze numerically the complete system by employing a finite element code and to compute the motions of the complete system under typical wind conditions at the site (wind velocities between 5 to 60 mph). The second phase of the study consisted of an experimental effort during which one of the illumination towers was instrumented and motion data was collected for various wind conditions. The final phase of the study included the evaluation of the numerical as well as the experimental data that had been obtained from the preceding steps. This evaluation included the identification of modes of vibration in the frequency domain, filtering of data for acescent of modal effects, and comparisons between experimental and numerical results.

This Research Summary is part of Report 2024-25, "Development of a smart phone app to warn the driver of unintentional lane departure using GPS technology."