Principal Investigator: Justice Appiah
Sponsors & Partners
University of Nebraska-Lincoln Civil Engineering Department
About this Project
Brief Project Description & Background
Expected increases in freight-carrying heavy truck and rail traffic in the Region VII area raises geometric design, safety, and operational concerns because of sight distance restrictions, low acceleration and deceleration capabilities characteristics, and the ability to maintain speeds particularly on steep grades. This project demonstrates how micro-simulation models may be adapted to: (i) serve as useful tools for understanding the issues raised by high truck and rail volumes; and (ii) assess potential investment and operational alternatives
To develop a framework for incorporating the unique operating characteristics of multi-modal freight networks into the calibration process for microscopic traffic simulation models. Because of the nature of heavy freight movements in Region VII (Nebraska, Iowa, Missouri, Kansas), this project will focus on heavy trucks and trains.
The calibrated model may: (i) provide the practitioner, working on multi-modal networks, the ability to perform realistic level of service analysis on highway sections with very high percentages of heavy vehicles for which standard HCM procedures may not apply; (ii) be used as a platform for optimizing traffic signals in urban networks that have significant muti-modal freight movements.
This research will develop a framework for incorporating the unique operating characteristics of multi-modal freight networks into the calibration process for microscopic traffic simulation models. Because of the nature of heavy freight movements in USDOT Region VII (Nebraska, Iowa, Missouri, Kansas), this project will focus on commercial vehicles and trains. In particular, a genetic algorithm (GA) based optimization technique will be developed and used to find optimum parameter values for the multi-modal vehicle performance model used by the microscopic traffic simulation model, VISSIM. The procedure will be implemented using a current micro-simulation model of the Nebraska State Highway System. The current VISSIM model will be expanded to account for both truck traffic and rail networks and will be developed such that the model can readily be updated as new information (such as ITS data) becomes available. At present, the Highway Capacity Manual (HCM), which is the most common reference for analyzing the operational characteristics of highways, only provide guidelines for heavy vehicle percentages of 25 or less. However, significant portions of the interstate 80 (I-80) in Nebraska have heavy vehicle percentages greater than 25 percent. It is expected that the procedure developed in this research will significantly improve the accuracy of simulations involving networks with substantial heavy vehicle traffic. As part of this project, the calibrated model will be tested for its suitability for performing operational analysis on urban and rural networks with very high heavy vehicle percentages for which standard procedures such as those of the HCM do not apply. Two test cases will be used to demonstrate the potential usefulness of the procedure â€“ (i) the I-80 corridor in Iowa-Nebraska; and (ii) a highway-rail grade crossing in Lincoln, Nebraska.