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Traffic Demand Modeling and Origin-Destination Matrix Estimation
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

An origin-destination (OD) matrix describes the travel demand between all pairs of origins and destinations in a traffic network. OD-matrices are essential input for most types traffic models, both for long-term planning, where the actions are meant to be permanent, and for short-term planning, where the operational situation is managed. This paper is a literature overview of models and methods for obtaining reliable OD-matrices.

We present the Four-stage model which is commonly used for sequentially computing the number of trips starting and terminating at the centroid nodes, the distribution to travel demand between origins and destinations, the split onto different travel modes and the choice-based assignment of routes and links in the network. Further, we identify the information contained in traffic counts as an important source for adjusting the computed OD-matrix. The generic OD-matrix estimation problem from link flow observations is formulated and we discuss different solution techniques and how they relate to the assumptions used for the assignment of travel demand to routes and links.

Time-dependence is a fundamental difference between the model types. A time-independent (static) model describes a steady state, which represents and average situation. If the interaction between sequential time periods is to be analyzed, however, a dynamic model is required. The time dimension is a complicating factor, since not only the route choice, but also the flow propagation must be taken care of in the model. Especially those models where the OD-matrix is to be estimated in real-time, must be simplified as to the computational effort.

National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-102432OAI: diva2:677731
Available from: 2013-12-10 Created: 2013-12-10 Last updated: 2013-12-10
In thesis
1. Origin-destination matrix estimation from traffic counts
Open this publication in new window or tab >>Origin-destination matrix estimation from traffic counts
2003 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

For most kind of analyses in the field of traffic modeling, there is a need for origin-destination (OD) matrices, which specify the travel demands between the origin and destination nodes in the network. The process of obtaining OD-matrices is long, complicated and expensive. The counting of traffic, which provides link flow observations, therefore is an opportune possibility for easily up-dating the information on the travel demand. This thesis concerns the estimation of OD-matrices from traffic counts. 

We will consider the problem to estimate OD-matrices for both time-indepenent and time-dependent models. Many models have been suggested for the time-independent case, where the quantities represent and average situation. If a user equilibrium is assumed for the link flows in the network, a bilevel problem structure is recognized, where the link flows are implicitly expressed as a traffic assignment of the present OD-matrix. A descent heuristic, which is an adaptation of the well-known projected gradient method, is proposed. Special attention is given to the problem of approximating the Jacobian matrix, which expresses the change of a certain link flow with respect to a unit change of the travel demand in a certain pair of origin and destination.

When a time dimension is introduced, the estimation problem becomes more complex. Besides the problem of distributing the travel demand onto different routes, the flow propagation with respect to time must be handled. A general time-dependent extension of the estimation problem is given and the complications with dynamic traffic assignment are discussed. In a case study, the conventional solution technique is improved by introducing pre-adjustment schemes, which the structure of the information provided by the OD-matrix and the link flow observations.

Place, publisher, year, edition, pages
Linköpings Universitet: Linköpings universitet, 2003. 4 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1057
National Category
Engineering and Technology
urn:nbn:se:liu:diva-38828 (URN)45788 (Local ID)91-7373-785-2 (ISBN)45788 (Archive number)45788 (OAI)
2003-11-28, Sal TP45, Hus Täppan, Linköpings Universitet, Campus Norrköping, Linköping, 10:15 (Swedish)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-12-10

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