Residual Queues Research Articles

Analytical Models for Protected plus Permitted Left-Turn Capacity at Signalized Intersection with Heavy Traffic

This paper presents theoretical analysis of left-turn operations under heavy traffic. When traffic demand is heavy, residual queues from previous cycles may occur and contribute to blockage of the left-turn bay by adjacent through traffic. Such blockage reduces the left-turn capacity and is a random phenomenon. An improved model for protected left-turn capacity is first proposed, taking into account the influence of residual queues and blockage by through traffic. In addition, the classic model always overestimates the potential permitted left-turn capacity when opposing traffic is heavy. The potential permitted left-turn capacity is then modeled in a probabilistic way, and a simple estimation is suggested by investigating its relation to the classic model. Furthermore, because left-turn capacity may vary in response to a blockage, the coefficients of variance for protected left-turn capacity and for queue clearance time are introduced to evaluate the protected left-turn timing plan. The developed analytical models are validated with CORSIM simulations.

Capacity-Constrained Traffic Assignment in Networks with Residual Queues

This paper proposes a capacity-constrained traffic assignment model for strategic transport planning in which the steady-state user equilibrium principle is extended for road networks with residual queues. Therefore, the road-exit capacity and the queuing effects can be incorporated into the strategic transport model for traffic forecasting. The proposed model is applicable to the congested network particularly when the traffic demands exceed the capacity of the network during the peak period. An efficient solution method is proposed for solving the steady-state traffic assignment problem with residual queues. Then a simple numerical example is employed to demonstrate the application of the proposed model and solution method, while an example of a medium-sized arterial highway network in Sioux Falls, South Dakota, is used to test the applicability of the proposed solution to real problems.

Time-Dependent Model for Departure Time and Route Choices in Networks with Queues

A multiperiod time-dependent model for departure time and route choices in networks with residual queues is presented. The proposed model is meant to be used for strategic transportation planning, taking into account the effects of time-dependent queues that are carried over to the next period. The departure time choice is based on an incremental logit model, whereas the route choice follows an extended user equilibrium (UE) principle. This model is formulated as the variational inequality (VI) problem, which accounts for the major features of networks with residual queues, including the effects of queue delay and traffic flow truncation due to road exit capacity. The Jacobi method is used to solve the VI problem. In the proposed solution method, the diagonalization subproblem is equivalent to the steady state extended UE assignment for networks with queues. A simple numerical example is used to illustrate the application of the solution method.

A Computer Control Scheme for Critical-Intersection Control in an Urban Network

In periods of traffic congestion, residual queues at intersections or the blocking of lanes limit the efficiency of synchronized signalization. A computer control scheme is developed that concentrates upon providing real-time, traffic-responsive corrective action for a “critical intersection,” defined as a point in the network at which primary driver routes cross or those where congestion has arisen for other reasons, such as in the aftermath of an accident or stall. The sub-optimal scheme attempts to minimize the total delay, measured in vehicle-seconds, not only to all users of the intersection but also of accumulated delay at downstream intersections. Within upper and lower limits on the cycle time, the control of the traffic signal is variable split and variable cycle-length in response to traffic needs. A simulation evaluation of the method is given via several test cases, using as a base case actual traffic data from San Jose, California.