Snowplow operators work in difficult, often low-visibility conditions. A new system assists drivers in knowing their lane position and warns of approaching obstacles. After operators tested the system over two winters, researchers gathered feedback, revised the system and readied it for the next step in statewide deployment.
Continue reading Refining the Lane Boundary Guidance System for Snowplow OperatorsTag Archives: LRRB
Assessing Stormwater Ponds for Phosphorus Retention
Stormwater ponds and wetlands reduce flood risk and keep pollutants from entering other bodies of water. As ponds age and change, however, they may not perform as designed. Local agencies now have tools to assess whether a pond is likely to retain phosphorus, which can help guide stormwater management efforts.
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Guidance for Cities Considering Speed Limit Changes
The issue of reducing speed limits to increase public safety is an emotional, political, and controversial topic that has been debated by safety advocates, engineers, politicians, transportation officials, and the public for many years. A statutory change in 2019 put a spotlight on the topic, requiring a deeper look into how speed limits are established and the effectiveness that lowering speed limits has on reducing vehicle traveling speeds, as well as the impacts on pedestrian and bicycle traffic.
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Alternative Transit Approaches for Rural Communities
Meeting transit needs in rural communities can be challenging. A new pilot study demonstrated the benefits of using mobile technologies and existing assets to enhance transit services and improve local economies.
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Connecting smart vehicles with traffic signals could reduce fuel use
Originally published in Catalyst, July 18, 2022.
Green means go and yellow means go faster—so goes a wry take on driver behavior at traffic signals. But it’s not just travel time that increases when you brake for a red: Fuel consumption does, too. Could transmitting signal data to connected vehicles (CVs) reduce stop-and-go cycles and fuel use? U of M researchers say yes.
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Impacts of Autonomous Vehicles on Operation and Maintenance of Minnesota Roads
As autonomous vehicle technology evolves, transportation agencies want to understand how road maintenance and traffic operations may also need to evolve. New research begins to identify potential needs and further questions for winter road maintenance, work zones and traffic flow.
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Using Rumble Strips to Encourage Stops at Rural Intersections
Vehicle crashes in rural areas often happen at intersections. Transverse rumble strips placed before a stop sign can be an effective safety measure that warns drivers approaching an intersection. Recent research has provided an increased understanding of the most effective rumble strip designs and noise characteristics to help county traffic engineers decide when and where to deploy the strips.
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Comparing the Cost-Effectiveness of Asphalt Binders for Local Roads
Asphalt pavements with polymer-modified binders (PMBs) perform better than pavements with unmodified asphalt binders. While pavements with PMBs may cost more initially, performance is improved in the long run. In a recent study, researchers compared the performance and life cycle costs of modified and unmodified binders and found that modified binders are more cost-effective, even for local low-volume roads.
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With new signal timing method, Twin Cities traffic could flow more smoothly
Reprinted from Catalyst, May 12, 2023.
Eliminating intersection bottlenecks is one of the most persistent and difficult challenges for traffic engineers. A new mathematical theory called “max-pressure signal control” has been proven to achieve maximum throughput for entire city road networks, but it has not yet been used in practice. In a new study, U of M researchers brought the theory several steps closer to real-world use and found that it could offer many benefits to Minnesota road users.
“For most intersections and demand periods, we found that max-pressure control offered significant improvement over current signal timings,” says Michael Levin, an assistant professor with the Department of Civil, Environmental, and Geo- Engineering. “Large reductions in delay—sometimes over 50 percent—suggest that this new method of signal timing could achieve higher throughput during peak demand and be more responsive to queues.”
To achieve these findings, researchers began by addressing some aspects of max-pressure signal timing that would make it difficult to implement in a real-world setting. First, researchers addressed its assumption that all roadways had separate turning lanes by adapting the mathematical model to accommodate mixed travel lanes.
Another drawback of the original formula is that the signal control doesn’t operate on a cycle; this could cause long wait times when demand is uneven and make the signal cycle unpredictable for both drivers and pedestrians.
“To solve this issue, we modified the formula to include a maximum waiting time and require that the phase selection follows a cycle,” Levin says. “This allows traffic engineers to create an ordered set of phases for each intersection.”
Once the updated version of max-pressure control was developed, researchers tested it in simulations of two corridors in Hennepin County, Minnesota. The simulations revealed numerous potential benefits including reduced environmental impacts and reduced road user costs resulting from travel time savings and lower fuel costs.
“The findings show that our new max-pressure control formula will reduce the average queue length during peak hours and that vehicles will not wait as long at intersections,” Levin says. “We can also predict higher throughput and faster vehicle speeds, all of which will mitigate congestion and improve quality of life.”
In addition, a cost-benefit analysis shows that the total value of travel time savings is considerably larger than the cost to implement max-pressure control.
The project’s success led researchers to explore the possibility of a real-world pilot project with available traffic signal hardware. They found that the traffic signal technology currently used in Hennepin County could be upgraded to support a pilot study, laying the groundwork for a future real-world test of this promising new signal timing method.
The project was funded by the Minnesota Local Road Research Board (LRRB). Phase two of the work, also funded by the LRRB, is underway.
Writer: Megan Tsai
More Information
- MnDOT Phase I Project page
- Final report, Phase 1
- Phase 2 Project Page
New Project: Mitigating Tenting of Transverse Cracks and Joints in Asphalt Pavement
More than 60% of Minnesota’s roadways consists of asphalt pavement. When transverse cracks occur in asphalt, our frigid winters can cause a secondary distress known as pavement tenting, crack heaving, or lipping. As ice accumulates in the base materials underneath, it causes pavement on both sides of the transverse cracks and joints to heave.
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Crossroads 