Delays in freight shipments caused by highway bottlenecks can harm a region’s economy and productivity. It’s no surprise, then, that freight mobility is a key concern for many major metropolitan areas—and the Minneapolis–St. Paul metro area is no exception.
To improve freight management planning and guide infrastructure decision making, planners at the Minnesota Department of Transportation (MnDOT) realized that they needed performance data specific to heavy truck traffic.
To meet this information need, MnDOT funded a project led by Chen-Fu Liao of the U’s Minnesota Traffic Observatory to integrate data about heavy truck movement along the Twin Cities’ freight corridors with MnDOT’s existing data. The goal was to create freight mobility and reliability measures and identify significant freight bottlenecks.
Liao’s team analyzed and validated truck data collected from several sources, including 12 months of truck data collected using GPS on 38 freight corridors in the Twin Cities area. (The GPS data was provided by the American Transportation Research Institute, which also provided technical support for the study.) Next, researchers processed the raw truck data and used it to create freight performance measures including corridor target speed, truck volume, truck mobility, truck delay per day, and truck travel time reliability.
Based on these performance measures, the research team identified and ranked the truck bottlenecks in the Twin Cities. “We found that most of the bottlenecks are located near intersections,” Liao says. “We also discovered that contrary to prior assumptions, trucks sometimes face delays due to road curvature, grade, or geometry that do not cause problems for general traffic.”
This research offers a wealth of information that will complement data already being collected for transportation planning to improve truck movement on Twin Cities highways and develop a statewide freight system plan. The project also identifies issues that may shape future investments. For example, MnDOT may eventually look to areas with high levels of trucking activity to identify where there is a need for increased truck parking facilities.
Read the full article in the August issue of Catalyst.