Capacity-constrained Traffic Assignment in Network with Residual Queues and Implementation in EMME/2 Tel.: , 16th International EMME/2 User’s Group Conference Albuquerque, New Mexico, Mar , 2002 Yanping Zhang Bucher, Willis & Ratliff Corp Ward Pkwy, Kansas City, MO Tel.: , 16th International EMME/2 User’s Group Conference Albuquerque, New Mexico, Mar , 2002

Network with Residual Queues Residual Queues - Overcapacity flow Residual queue delay Link outflow <= Link exit capacity Unbalanced O-D flow Spill-back queues on upstream link

Basic Assumptions for Assignment 1)Assignment for single time period (e.g. peak hour period); 2)Fixed O-D demands; 3)Fixed exit capacity for each link; 4)Vehicles in the residual queue, will follow the chosen route to reach destinations in the next period; 5)Link cost consists of travel delay cost and the residual queue delay cost; 6)Drivers always choose thre shortest routes 7)No spill back effect on travel times in upstream links.

Simple Example

Comparison of Assignment Results

Assignment Model Formulation

User Equilibrium Assignment in Network with Queues

Solution Method Adding shadow links and modifying cost function Shadow links (only for carrying queues)

Path Operator in EMME/2 Cut-off path operator (splitting the queue-delay path flow)

Equivalent Model in the Modified Network

Approximation of Link Cost Function

Solution Algorithm

Example

Conclusion Model for assignment in network with Queues; Solution method with modified network; No consideration of queue spill-back Extension to Multiple period Assignment.