Blog Archives

Untangling the safety impacts of Minnesota’s I-35W improvements

MnPASS system on I-35W in Minneapolis, Minnesota.With the aim of reducing congestion on the Twin Cities’ highly traveled I-35W corridor between the Minnesota River and I-94, the Minnesota Department of Transportation (MnDOT) began a major set of I-35W improvements in 2009 as part of the Federal Highway Administration’s Urban Partnership Agreement (UPA). Among the improvements was the addition of a priced dynamic shoulder lane (PDSL) on parts of the 17-mile stretch of highway; however, following the opening of these improvements, the frequency of rear-end crashes increased in certain sections—especially in the PDSL regions.

To untangle the underlying causes of this increase, MnDOT enlisted the help of researchers in the Department of Civil, Environmental, and Geo- Engineering. “Our primary objective was to determine if these increases were direct effects of the improvements or if they were due to changes in the traffic conditions,” says Professor Gary Davis, the principal investigator. “MnDOT was interested in extending some or all of these improvements to other corridors but needed to know what the safety impacts were to aid its decision making.”

Posted in Infrastructure, Safety, Technology, Traffic operations, Transportation research, Urban transportation

New recommendations aim to help turfgrass thrive on Minnesota roadsides

Truck watering a narrow strip of roadside turfgrassKeeping Minnesota’s roadsides green is about more than just aesthetics—healthy turfgrass can improve water quality, reduce erosion and road noise, and provide animal habitat. However, harsh conditions such as heat, drought, and salt use can make it difficult for roadside turfgrass to thrive.

In 2014, as part of a study funded by the Minnesota Local Road Research Board (LRRB), researchers in the Department of Horticultural Science identified a new salt-tolerant turfgrass mixture that could be used on Minnesota roadsides. But, when the Minnesota Department of Transportation (MnDOT) began using the mixture, called MNST-12, the agency experienced a series of installation failures.

Now, led by Professor Eric Watkins, the research team has identified new best management practices for installing and establishing this type of salt-tolerant turfgrass. The study, funded by the LRRB, specifically focused on watering practices, soil amendments, and planting date for both seed and sod.

Posted in Environment, Transportation research

CTS Research Conference to explore funding, policy innovation

In November, CTS will conclude our 30th anniversary celebration at the annual Transportation Research Conference. The one-day event will celebrate CTS’s first 30 years and explore what comes next by presenting new learning, emerging ideas, and the latest innovations in transportation.

The conference will be held November 2 at the Commons Hotel on the U of M east bank campus. Plenary sessions will explore how we pay for transportation infrastructure and highlight transportation policy innovation.

Posted in 30th anniversary, Events, Transportation research

Minnesota freight market profiled in new paper

Performance of the freight system in Minnesota profoundly affects economic competitiveness. But perspectives vary on what constitutes and contributes to an attractive, competitive freight environment. Differences among various interests—carriers, retailers, consumers, and government—give rise to a certain competitive tension underlying critical decision making and investment involving freight.

To make sense of it all, the Minnesota Freight Advisory Committee (MFAC) in June published Components of an Attractive Minnesota Freight Market (PDF). The white paper, which identifies key aspects of an attractive freight market in Minnesota, is the first in a planned MFAC series about freight transportation issues important to Minnesota’s economy.

Posted in Economics, Freight, Transportation research

New warning systems aim to reduce rear-end crashes on Minnesota freeways

To reduce congestion and improve safety, the Minnesota Department of Transportation (MnDOT) has deployed active traffic management (ATM) technology on two freeways in the Twin Cities. The ATM system incorporates intelligent lane control signals placed over selected lanes at half-mile increments to warn motorists of incidents or hazards ahead.

Using this existing ATM infrastructure, U of M researchers have developed and field-tested two prototypes for queue warning systems in a new MnDOT-funded project. The warning systems specifically focus on preventing rear-end collisions—the most frequent type of crash on freeways.

Posted in Intelligent Transportation Systems (ITS), Safety, Technology, Traffic operations, Transportation research, Urban transportation

U of M researchers are helping build better bridge repairs

This summer, U of M researchers are bringing bridge girders into their lab to help MnDOT evaluate a repair method that could ultimately reduce traffic interruptions caused by infrastructure repairs.

The salting of bridge and roadway surfaces during Minnesota winters can create highly corrosive conditions that result in damage to bridges. Such was the case with the Trunk Highway 169 Nine Mile Creek Bridge near Edina and Minnetonka, where leaking expansion joints caused corrosion to elements responsible for the strength of bridge girders: shear reinforcement, prestressing strands, and the surrounding concrete. MnDOT repaired the damaged girder ends in 2013 by encasing them using a system of steel dowels, additional shear reinforcement, and sprayed concrete. MnDOT was able to make the repairs without traffic interruption.

Now, the bridge is being replaced, and U of M professor Carol Shield and her team of researchers are evaluating the effectiveness of the 2013 repair. The researchers’ goal is to determine if the repair strengthened the corrosion-damaged girders to a level similar to noncorroded girders. If proven effective, MnDOT could use this type of repair to lengthen the useful life of existing bridges and save travelers time and frustration caused by repair-related traffic delays.

Posted in Bridges and structures, Infrastructure, Maintenance, Transportation research

How equitable is bicycling infrastructure?

As the movement to promote bicycling as a means of transportation has grown, so has the amount of money governments and nonprofit organizations are investing in the nation’s urban bicycling infrastructure. A concern, however, is whether these investments are distributed equitably among neighborhoods.

In a new study, U of M researchers looked at this issue using Minneapolis as a case study and found that though inequities still exist, equity is improving.

Posted in Accessibility (access to destinations), Bicycling, Planning, Transportation research, Urban transportation
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