Early preventive maintenance of concrete pavement—maintenance performed in the first five to seven years of pavement life—is a low-cost way to increase pavement service life. But no quantitative evaluations of service life extension have been conducted that compare early intervention to late or no intervention.
Without these comparisons, meaningful determinations of pavement life extension operations cannot be made. Federal Highway Administration (FHWA) research has found that agency projects focused on the end-of-service life may redirect funds from rehabilitation projects that could improve overall system quality.
Intersections can be controlled through pretimed systems or vehicle-actuated systems, which detect the presence of a vehicle. Good vehicle detection is the foundation of actuated systems. While loop detectors have been effective workhorses of vehicle detection for MnDOT, changes in vehicle fleets—for example, the use of nonferrous materials—and an increased need to detect vulnerable road users has resulted in an increased use of nonintrusive detection technologies (NIT).
Understanding pedestrian and bicyclist flows is vital to distributing a limited construction budget to new infrastructure for improved safety on specific roads. Unfortunately, statewide data collection for active transportation flows is challenging.
MnDOT and local agencies historically have lacked estimates of bicycle and pedestrian traffic on Trunk Highways and County State Aid Highways.
Since about 2016, MnDOT has begun monitoring bicycle and pedestrian flow at more than 25 locations across the state, but, given the small number of counters and the variability of flows in response to variations in weather across Minnesota, these monitoring data are insufficient for estimation of Annual Average Daily Bicyclists and Annual Average Daily Pedestrians.
One option for obtaining travel data without expensive infrastructure is relying on mobile data collection.
As autonomous vehicles (AVs) become increasingly more numerous on roadways, they have the potential to substantially alter traffic flow. New vehicles today have many driver-assisting (or SAE Level 1) features—such as adaptive cruise control, parking assistance, collision avoidance, emergency braking and lane-keeping assistance—which still require a hands-on driver. However, as technology advances toward eventual SAE Level 4 automation, vehicles will be able to function without drivers, which will likely change the shape of traffic flow.
Building on previous MnDOT-sponsored work, researchers have developed a nondestructive method of assessing pavement thickness using 3D ground-penetrating radar (GPR). A vehicle equipped with an array of transmitting and receiving antenna pairs travels at traffic speed collecting full-width GPR data for analysis, minimizing the amount of pavement coring required.
Using an earlier lane departure warning system (LDWS) that employs standard GPS data rather than expensive cameras or maps, Minnesota researchers have enhanced and refined the system, moving closer to an affordable product to warn drivers about dangerous lane drift and approaching curves.
In recent years, many U.S. cities have been installing separated bicycle lanes (SBLs) as part of their nonmotorized transportation networks. SBLs are bicycle pathways that employ paint and a vertical element as a buffer to separate motor vehicle traffic from bicycle traffic. They reduce crash risk, increase safety and comfort, and encourage more people to use bicycles as transportation.
MnDOT and local agencies control stormwater runoff from roadways through a range of settlement, filtration and infiltration facilities, such as wet ponds, infiltration basins, trenches and swales. Infiltration facilities have been used for more than 30 years, but a high rate of failure has been tied to inaccurate determination of soil infiltration rates. Researchers developed new tools and protocols to provide designers and engineers with the accurate infiltration measures they need, from initial site selection through construction. These tools and methods will support the development of successful stormwater infiltration facilities along Minnesota roadways.
Manufacturers are developing vehicles that can “talk” to each other. “Connected vehicles” will be able to convey their position, speed and acceleration. Sending this information to other vehicles and relevant infrastructure is expected to enhance highway safety, but it also may help transportation agencies better manage traffic.
Crossroads 