Research Reports

This report presents an evaluation of the first five years of operation for the I-35W traffic management system, which extends along a 17 mile section of freeway south of downtown Minneapolis. The system was developed as part of the I-35W Urban Corridor Demonstration Project which combined the benefits of traffic management with express bus transit service.

The objectives of this study were to document from actual measurements the changes in auto occupancy rates over the last six years (1974 through 1979), to establish a broader base to measure future changes in auto occupancy rates, and to attempt to measure the daily variations in auto occupancy rates while eliminating seasonal variations by collecting data every spring.

This research summary accompanies Report 2024-16, "Assessing Pavement Markings for Automated Vehicle Readiness," published in June 2024

New technologies are being added to vehicles at a growing rate to assist drivers and even fully take over the driving task in some situations. These technologies are generally camera-based and typically rely on pavement markings to maintain vehicle position and navigate the roadway. As drivers become more reliant on these systems, and for these systems to meet their potential safety benefits, the pavement marking infrastructure needs to be optimized to provide adequate roadway delineation. What is somewhat unknown is how different this optimized pavement marking system is from current practice and how different are the visibility needs of vehicle systems and the human eye. This project explores how various pavement marking configurations impact automated driving systems' ability to track the markings and maintain lane position. Evaluations take place in Texas and Minnesota on closed-course, open-road, and pavement marking test areas. Various camera-based systems are used to view the markings and generate feedback on the impact of the marking configurations and characteristics on the ability of the camera systems to track the markings. The research team analyzes the test results and provides recommendations to improve pavement markings to increase the function and reliability of camera-based pavement marking tracking driver assist features such as lane centering. The goal is to improve and maintain markings so the driver assist features can function reliably and yield safety improvements by reducing crashes, especially run-off-road crashes.

This appendix is part of Report 2004RIC04. "Best Practices for Boulevard Tree Selection."

The purpose of this study was to evaluate the effect of formed polystyrene concrete cylinder molds on concrete strength. This report describes the various treatments given to cylinders, which were cast in steel, fiber, and polystyrene molds and the statistical analysis which was made on the 28 day compressive strength results. A recommendation is made concerning the use of polystyrene concrete cylinder molds.

This report describes a laboratory evaluation of the physical characteristics of shrinkage compensating cements when additives are used. Two admixtures were studied, Dow Corning 777B, a reactive polysiloxane, which increases the durability or resistance to weathering, and Sika Set, a low-shrinkage, final set accelerator. The concrete used was a standard Minnesota Highway Department bridge deck design mix (3Y43). The two additives generally improved the physical characteristics of the ChemComp shrinkage compensating cement but greatly reduced the durability of the concrete in the freeze-thaw tests. It is recommended that Sika Set and Dow Corning 777B not be used in ChemComp cement concrete due to the low durability which results. The use of other additives with ChemComp cement should be evaluated before use in the field.

The attached report covers the work which has been in progress since 1955 to determine whether Minnesota concrete aggregates have a detrimental reaction with the alkalis present in Portland Cement. It has been found by extensive research elsewhere that, when such reaction does occur, it may produce volume changes of the concrete thus causing internal stresses and consequent disruption of the concrete This study was prompted by the occurrence of extensive "D" cracking and subsequent serious spalling at many of the joints in the 1941 experimental concrete paving project between Worthington and Brewster. It was suspected that the deterioration of the concrete might have been caused lay alkali-aggregate reactivity, The results of this study indicate that alkali-aggregate reactivity was not a contributing factor on the experimental project and probably will not occur with any Minnesota concrete aggregates.

In 1979, the Minnesota Department of Transportation (Mn/DOT) felt that the aggregate supply would become critical in about 20 years. Hence, in December 1979, Mn/DOT acting as an agent of the Local Road Research Board, requested Ernest K. Lehmann & Associates of Minneapolis to study the aggregate supply problem in four selected areas of the state. The objectives of the study were (1) to determine permitted reserves, and the rate and causes of aggregate depletion in Polk County and vicinity, St. Cloud and vicinity, Hennepin County, and Rochester and vicinity; and 2) to determine methods used at the local, state and national levels to conserve, and enhance aggregate supplies. Aggregate reserves within permitted properties in the four pilot areas were determined through interviews with pit and quarry operators and with government personnel. Demand for aggregate was obtained by analyzing the construction activity, both public and private, and by applying aggregate-content factors to the construction dollar estimates. Review of conservation methods being used by other states and in Canada suggest several methods for conserving and enhancing aggregate supplies in Minnesota. The remaining years of supply from permitted properties in the four pilot areas range from 9 to 22 years. Land use regulations are the single most important determinant of future aggregate availability, especially in metropolitan areas. Model legislation termed "The Aggregate-Land Protection Act" is suggested for the conservation and orderly development of aggregate lands. Other supply enhancement measures suggested in the report are the recycling of aggregate in pavement and buildings, increased use of substitutes such as flyash and boiler slag, maximizing the use of pit-run materials by improving processing techniques, and underground mining of limestone.

In 1979, the Minnesota Department of Transportation (Mn/DOT) felt that the aggregate supply would become critical in about 20 years. Hence, in December 1979, Mn/DOT acting as an agent of the Local Road Research Board, requested Ernest K. Lehmann & Associates of Minneapolis to study the aggregate supply problem in four selected areas of the state. The objectives of the study were (1) to determine permitted reserves, and the rate and causes of aggregate depletion in Polk County and vicinity, St. Cloud and vicinity, Hennepin County, and Rochester and vicinity; and 2) to determine methods used at the local, state and national levels to conserve, and enhance aggregate supplies. Aggregate reserves within permitted properties in the four pilot areas were determined through interviews with pit and quarry operators and with government personnel. Demand for aggregate was obtained by analyzing the construction activity, both public and private, and by applying aggregate-content factors to the construction dollar estimates. Review of conservation methods being used by other states and in Canada suggest several methods for conserving and enhancing aggregate supplies in Minnesota. The remaining years of supply from permitted properties in the four pilot areas range from 9 to 22 years. Land use regulations are the single most important determinant of future aggregate availability, especially in metropolitan areas. Model legislation termed "The Aggregate-Land Protection Act" is suggested for the conservation and orderly development of aggregate lands. Other supply enhancement measures suggested in the report are the recycling of aggregate in pavement and buildings, increased use of substitutes such as flyash and boiler slag, maximizing the use of pit-run materials by improving processing techniques, and underground mining of limestone.