Evaluating Induced Changes in Routing Behavior After the Implementation of the Northwest Corridor Managed Lane
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Boodhoo, Ronald Omadath
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Abstract
This dissertation presents a methodology for evaluating the impact of the Northwest Corridor managed lane on total travel time and modelled route choice. The Northwest Corridor Express Lanes (NWC), completed in September 2018, added a total of 29.7 miles of barrier separated express lanes along I-75 from Akers Mill Road to Hickory Grove Road and along I-575 from I-75 to Sixes Road. The preponderance of research evaluates the effectiveness of managed lane implementations, primarily by computing the travel time savings between adjacent general-purpose lanes and express lanes under an assumed value of time. Few research studies examine differences in modelled route choice which are attributed to changes in total travel time from trip origin to trip destination after the implementation of a managed lane system which utilizes left turn exits and entries, while restricting access to general purpose lane exits along I-75 for Express Lane users. The fundamental difference between the NWC and other managed lane facilities is that the NWC have new dedicated access points which can only be traversed by Express Lane users. Drivers would enter and exit the managed lanes without crossing the general-purpose lanes and are forbidden from using these dedicated access points. The mandatory usage of left turn entries and exits to and from the Northwest Corridor managed lane may impact the total travel time experienced by motorists entering and exiting the managed lane particularly by impacting the distance traveled along arterial routes. A sensitivity analysis was conducted on toll rates charged per mile within a VISSIM® (version 9.0) traffic simulation to observe how modelled route choice is impacted after the implementation of the NWC, from trip origin to trip destination, from 5 A.M. to 11 A.M. The results of the VISSIM® simulations can be used to enhance the development of lane choice models, which do not currently handle managed lane systems which restrict access to general purpose lane exits. The traffic simulation, which includes 29.7 miles of the Northwest Corridor managed lane Corridor, 162 signalized intersections and approximately 38 centerline miles of Interstate, and over four hundred miles of arterial routes were used to model traffic flow from both Interstate and arterial routes to and from the managed lane. An Activity Based Travel Demand Model (ABM) provided by the Atlanta Regional Commission (ARC) is used to model trip entry and exit points for use within the traffic simulation. A sensitivity analysis on toll rates charged per mile was conducted within a VISSIM® simulation to examine the impact of the Northwest Corridor managed lane on total travel time and modelled route choice. Results from three case studies indicated that estimated travel time savings occurred most consistently along routes that contained only arterial and managed lane routes, where the travel distance from trip origin to the managed lane access point is less than two miles. Some queueing occurs in advance of managed lane exits under two conditions, namely when travel demands are high, and when the speed variations between leading and following vehicles are significant due to merging behavior near the managed lane access points. The research found that estimated travel time savings were most significant in cases when there is extreme congestion along arterial routes and the proximity to the managed lane entry from the trip origin is less than two miles away. There are differences in travel patterns associated with the addition of dedicated Express Lane ingress and egress access points, particularly at Roswell Road, where Express Lane users save up to thirteen minutes of travel time. The dissertation concludes with a summary of results, discussion on research limitations, some advice for practitioners, and recommendations for future research.
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2026-05
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Dissertation (PhD)