United States Department of Transportation
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Edition:Final Report 2016–2019
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Abstract:Freight Intermodal Connectors (FICs), which are also known as “first mile/last mile roadways”, are roadway segments that link freight logistic hubs or freight-intensive land uses to main freight routes. This project focused on segments, corridors and intersections that connect Tennessee freight trucks to/from the major freeways from/to high‐priority facilities such as truck hubs, airport, rail, intercity bus terminals, etc. For efficient intermodal freight movement, these connectors must be in a desired service condition (operational, safety, and environmental) capable of accommodating freight needs. The evaluated FICs in Tennessee to identify deficiencies related to congestion, capacity, safety and emission needs. Crash analysis found that connectors leading to pipeline terminals have high crash rates compared to other type of terminals, while port terminal connectors have the lowest crash rates. Signal density was found to significantly affect the probability of crashes together with the presence of a two-way left turn lane (TWLT), which tends to decrease probability of crashes along these connectors. The presence of shoulders along intermodal connectors was found to help reduce the probability of crashes while the presence of curbs and gutters tends to increase crash frequency. Analysis indicated that most FICs with high crash rates were also operating at a lower traffic operations level of service especially for critical movements towards freight facilities. FIC operational and capacity evaluation was aimed at identifying deficiencies with respect to queueing, delay and level of service (LOS) at critical intersections. It was observed that intersection delays varied randomly without specific pattern related to the type of connector. Reliability measures for fluidity analysis were used to identify bottlenecks and related delay costs for some connector segments. Travel time reliability was used to locate the bottlenecks along freight intermodal connectors (FICs). The study collected GPS second-by-second data, then developed statistical regression models to establish the relationship between reliability performance measures. The study showed that freight connectors to and from pipeline terminals have the highest ranked bottlenecks during evening peak hours while those to bus terminals are at highest during the morning peak hours. Airport and port freight connectors were found to have moderately ranked bottlenecks during evening peak hours. A survey was conducted to evaluate FICs in Tennessee from the stakeholders’ (truck drivers’) perspective. The survey results showed the biggest issues that drivers are currently facing are recurring congestion along the FICs, signage, safety and security, bottlenecks, direct/indirect cost of congestion, on-time delivery, and the absence of safety features such as bike lanes, sidewalks, and pedestrian features. The study used Environmental Protection Agency (EPA) mobile source emissions model Motor Vehicle Emission Simulator (MOVES) to estimate truck emissions along the FIC segments on a second-by-second basis in combination with VISSIM simulation software. The MOVES model estimations were compared/combined with estimates from VISSIM to obtain accurate emission results. The VISSIM/MOVES model was used to determine emissions factors for carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM 2.5), and volatile organic compounds (VOC)along the FICs. TDOT should base the implementation of the study findings on the listed and ranked segments and intersection’s safety, operational, travel reliability and air pollution deficiencies. The implementation should include pavement resurfacing, signage, travel-way widening, intersection reconfigurations and signal re-design to mitigate delays, queuing and improve travel time and LOS. TDOT also can use the developed models for predicting crash frequencies along the FIC segments and microscopic models to estimate CO, NOx, PM 2.5 and VOCs emissions at project levels.
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