RECENT DEVELOPMENTS IN STOCHASTIC ASSIGNMENT MODELLING

Whilst it has become increasingly widely recognised in recent years that stochastic user equilibrium (SUE) assignment is the most appropriate way to model the aggregate effect of drivers' route choices, it has not yet found its way into widespread practical use for scheme appraisal. There are several plausible reasons for this, the most important probably being the limited availability of SUE routines within the best-known assignment software packages. Other contributory factors are that the two best-known stochastic loading processes have certain weaknesses: that due to Dial does not take account of overlapping paths, and the Burrell probit method relies on random number generation techniques. Furthermore, even when these loading methods are used within SUE, convergence is generally quite slow because of the use of the Method of Successive Averages (MSA) with its preset values of the step length at each iteration. This paper gives an overview of research which has been carried out by the authors (i) to develop a numerical (as opposed to simulation-based) probit loading method which takes account of overlapping paths but which does not require path enumeration; and (ii) to incorporate this probit loading process (or indeed a logit loading process) into an efficient algorithm for finding the SUE solution, through the estimation at each iteration of an optimal step length, thereby giving a much improved convergence rate than that provided by MSA. It is also shown that it is possible to extend the basic algorithm to allow for multiple user classes, junction modelling and elastic demand. (A)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00410683
• Corporate Authors:

  PRINTERHALL LIMITED

  32 VAUXHALL BRIDGE ROAD
  LONDON,   United Kingdom  SW1V 2SS
• Authors:
  • MAHER, M J
  • HUGHES, P J
• Publication Date: 1998-3

Language

• English

Media Info

• Features: References;
• Pagination: p. 174-9
• Serial:
  • Traffic Engineering & Control
  • Volume: 39
  • Issue Number: 3
  • Publisher: Hemming Group, Limited
  • ISSN: 0041-0683
  • Serial URL: http://www.tecmagazine.com/

Subject/Index Terms

• TRT Terms: Calculation; Computer programs; Demand; Drivers; Economic efficiency; Intersections; Iterative methods; Itinerary; Mathematical models; Methodology; Origin and destination; Probability
• Uncontrolled Terms: Efficiency; Selection
• ITRD Terms: 6464: Calculation; 285: Demand (econ); 1772: Driver; 5911: Efficiency; 6492: Iteration; 699: Itinerary; 455: Junction; 6473: Mathematical model; 9102: Method; 687: Origin destination traffic; 6534: Probability; 9072: Selection; 8645: Software
• Subject Areas: Data and Information Technology; Economics; Highways;

Filing Info

• Accession Number: 00752375
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD, ATRI
• Created Date: Sep 18 1998 12:00AM