Liao, Chen-Fu

Freight transportation provides a significant contribution to our nation’s economy. A reliable and accessible freight network enables business in the Twin Cities to be more competitive in the Upper Midwest region. Accurate and reliable freight data on freight activity is essential for freight planning, forecasting and decision making on infrastructure investment. A report entitled “Twin Cities Metropolitan Region Freight Study” published by MnDOT and the Metropolitan Council in 2013, suggested a need to understand where and when trucks are most affected by congestion. A framework for truck data collection and analysis was recommended to better understand the relationships between truck traffic and congestion in rush hours. Building upon our previous study to measure freight mobility and reliability along 38 key freight corridors in the Twin Cities Metropolitan Area (TCMA), this study leveraged our previous effort to implement the performance measures using the National Performance Measurement Research Dataset (NPMRDS) from the USDOT. The researcher team first worked with stakeholders to prioritize a list of key freight corridors with recurring congestion in peak periods in the TCMA. We used 24 months of NPMRDS data to measure travel time reliability and estimate truck delay at the corridor level and to identify system impediments during the peak hours. The objective is to use performance measures for assessing impact of truck congestions and identifying operational bottlenecks or physical constraints. Trucking activity nearby a congested area is examined to analyze traffic pattern and investigate possible causes of recurring congestions.

The Moving Ahead for Progress in the 21st Century Act (MAP-21) includes freight planning and project delivery provisions. Specific goals were identified in the National Freight Policy (NFP) to increase economic competitiveness, efficiency, and productivity; reduce congestion; and enhance the safety, security, and resilience of the freight network.
A reliable and accessible freight network enables the business to be competitive in the US. However, many urban roadways are facing challenges with traffic volumes being over capacity during peak periods. As a result, time and money are lost due to traffic congestion. Operational and design constraints such as interchange, steep grade, signalized intersection, work zone, merging, lane drop, and others, could contribute additional delays for commercial vehicles.
This study leveraged our previous effort to measure and identify truck bottlenecks in the Twin Cities Metropolitan Area (TCMA) by using the National Freight Performance Management Research Data Set (NPMRDS). The research team worked with stakeholders to prioritize a list of key truck corridors in the TCMA. Monthly NPMRDS data were processed to measure travel time reliability and estimate truck delay at the corridor level and then to identify system impediments during peak hours. Performance measures, including truck mobility ratio, travel