IntroTrfAsg - Introduction to the Traffic Assignment Toolbox

Description

The purpose of the toolbox is to solve traffic assignment problems. A good reference is Michael Patriksson's book "The Traffic Assignment Problem, Models and Methods".

To define the problem we need :

1) The Traffic Network : an oriented graph G where nn nodes represent places or cities, and na arcs represent links or roads.

2) The Link Performance Functions (also known as travel time functions): the travel time as a function of the flow in the arc. Seven formulae are used needing 4 parameters. Once a formula is chosen for the whole network, the parameters are defined in a 4 x na matrix.

3) The Origin-Destination traffic demand pairs (OD-pairs also called commodities) : are given by an initial node, a final node and a flow. The nd OD-pairs are defined by a 3 x nd matrix.

All the data is stored in a scilab structure called a "NetList" that plays the role of a geographic data basis which can be visualized by "ShowNet" and edited inside "metanet" or "scigraph". This NetList is build by "MakeNet".

The traffic assignment is computed by "TrafficAssig". The results are stored in the Geographic Data Basis and can be visualized with "ShowNet".

See Also

NetList  MakeNet  ShowNet  TrafficAssig