Dynamic Equilibrium Assignment Research Articles

Dynamic traffic analysis model of multiple passengers for urban public transport corridor

For researching travel choice behavior about different kinds of passenger-alone urban public transportation corridor, a dynamic multiple-passenger flow analysis model was proposed based on dynamic equilibrium assignment theory. Some factors which might influence passenger travel disutility were considered in the model, and they were closely related to the characteristic of passenger. And then a heuristic solution algorithm is developed to solve this model. Relying on MATLAB simulation, the model could reflect the time–space distribution of multiple-passenger flow along this corridor and gave a theoretically quantitative relationship among the passenger characteristics and departure time or path/mode choice. And some useful conclusions about travel choice behavior of different passengers were obtained finally. Compared with the actual data, the deviation of the simulation results is less than 20%, which shows the efficiency of the dynamic multiple-passenger flow analysis model clearly.

Quasi-continuous dynamic equilibrium assignment with departure time choice in congested unidirectional pedestrian networks

Although walking has been considered as an important transport mode, pedestrian modelling has received little attention in either academic or practising circles. There is an increasing need for methods that can be used to help the planning, design and management of pedestrian traffic systems. This paper presents a nonlinear programming formulation of the dynamic pedestrian equilibrium assignment problem based on the following assumptions. The pedestrian traffic system in a congested urban area can be modelled as a capacitated network with alternative walkway sections. People in this pedestrian network make such decisions as selecting departure time and walking path between origins and destinations (OD). The study horizon is divided equally into shorter time intervals of 5–10 minutes each, for which the pedestrian departure time matrices are given by a logit formula. It is dependent on the predetermined departure time costs and the equilibrium OD walking costs. In the proposed model, a ‘quasi-continuous’ technique is adopted to smooth out the transitions of various variables between time intervals and to satisfy the first-in-first-out discipline. A heuristic algorithm that generates approximate solutions to the model is presented. The numerical results in a real network shows that the model and algorithm proposed in this paper are able to capture the main characteristics of the departure time and route choices in congested unidirectional pedestrian traffic systems.

Quasi-continuous dynamic equilibrium assignment with departure time choice in congested unidirectional pedestrian networks

Quasi-continuous dynamic equilibrium assignment with departure time choice in congested unidirectional pedestrian networks

A dynamic traffic equilibrium assignment paradox

This paper explores the properties of dynamic flow patterns on two symmetrical networks: an “evening-rush-hour” network (E-net) with a one-to-many origin–destination (OD) pattern and a “morning-rush-hour” network (M-net) with a many-to-one OD pattern that can be obtained by reversing the direction of links and the origin and destinations of the evening-rush-hour network. Although conventional static traffic assignment produces exactly the same flow pattern for both networks, such a simple result does not hold for dynamic assignment. We show this result theoretically by using dynamic equilibrium assignment with a point queue model. Specifically, we first derive the closed form solutions of the dynamic assignment for both networks. We then identify the essential differences between the two dynamic network flow patterns by comparing the mathematical structure of the solutions. Furthermore, a type of capacity paradox (a dynamic version of Braess’s paradox [ Braess, D., 1968 . Über ein paradox in der verkehrsplanung. Unternehmensforschung, 12, 258–268.]) is identified in order to demonstrate the differences.

An integrated, dynamic approach to travel demand forecasting

This paper presents a unified approach for improving travel demand models through the application and extension of supernetwork models of multi-dimensional travel choices. Proposed quite some time ago, supernetwork models solved to stochastic user equilibrium can provide a simultaneous solution to trip generation, distribution, mode choice, and assignment that is consistent with disaggregate models and predicts their aggregate effects. The extension to incorporate the time dimension through the use of dynamic equilibrium assignment methods is proposed as an enhancement that is necessary in order to produce realistic models. A variety of theoretical and practical problems are identified whose solution underlies implementation of this approach. Recommended future research includes improved algorithms for stochastic and dynamic equilibrium assignment, new methods for calibrating assignment models, and the use of Geographic Information Systems (GIS) technology for data and model management.

SOME ASPECTS OF THE DYNAMIC EQUILIBRIUM ASSIGNMENT IN OVERSATURATED NETWORKS

The dynamic equilibrium assignment model dealing with an oversaturated network is here simplified by several assumptions such as uniform arrivals and departures at bottlenecks in order to easily analyse the formulation and the uniqueness of the solution. Based on the simplified model, it is concluded that the dynamic equilibrium assignment cannot be generally converted to the optimization problem as in the static assignment, since the objective function is hardly defined except for some special networks. Instead, the variational inequalities are formulated using route variables (route flows and costs). However, in general, the VI formulation with link variables is riot feasible. As an example illustrates, the route cost function is not monotonically increasing in route flows, which implies that a unique set of the equilibrium route flows would not be always expected.