Multi-modal transportation optimization of a local corridor

Abstract

The objective of this project is to redesign a one-mile section of the South Main Street Corridor in Harrisonburg, Virginia into a multimodal one that feasibly and safely integrates motor vehicles, bicyclists, and pedestrian traffic. Traditional traffic engineering practices emphasize optimizing vehicular traffic movement while treating pedestrian and bicyclist traffic movements as constraints. The focus of this research is to develop a way to maximize the capacity of existing right-of-way for all three traffic movements simultaneously, using a common metric of person-trips. Starting with standard equations from the Highway Capacity Manual for modal capacity of an intersection approach, the objective function for an optimization problem is developed. The objective function is the sum of capacity for each traffic movement measured in person-trips/hour, which normalizes the metrics. The input variables are flow rates for each movement that can vary based on scenario but cannot exceed their respective saturation flow rates. The outputs, or key design variables, are number of sublanes, which are unique to each traffic movement and define the geometry of the travel way. Combining all the sublane-widths results in the total width of the travel way that is constrained by the existing width of right-of-way. Therefore, through varying the flow rate per mode, different scenarios are evaluated that represent status quo, and shifts in corridor use. All other variables in the capacity equation are held constant. Based on the constraints, the objective function will yield a feasible region for which maximization of intersection efficiency will be found. The resultant combination of sublanes for each mode of transportation can then be implemented into the redesign model. This will alow for the most efficient flow of people through the intersection, regardless of mode choice, and could help promote policies and street design that prioritize alternatives to vehicular travel.