### Abstract

The design of an optimal road pricing scheme is not a trivial problem. Following the Dutch government’s kilometre charge plans, this paper focuses on the optimisation of link based toll levels differentiated in space and time. The optimal toll level design problem is formulated as a bi-level mathematical program. In the upper level we minimise an object function, e.g. the average travel time in the network, using a fixed number of price categories. At the lower level a dynamic traffic assignment model is used to determine the effects of differentiated road pricing schemes on the traffic system. Focus of the paper is on the upper-level where optimal toll levels are approximated. In the optimisation procedure different variants of a pattern search algorithm are tested in a case study. Inspection of the solution space shows that many local minima exist, so the selection of the initial solution becomes important. In the case study however it appears that in all local minima the value of the objective function is almost the same, indicating the fact that many different toll schemes result in the same average travel time. The case study is also used to test the performance of the different variants of the pattern search algorithm. It appears that it is beneficial to change more variables at a time and to use a memory to remember where improvement of the objective function has been made. First tests on a medium scale network showed that it is possible to apply the framework on this network, though further computational improvements are needed to apply the framework to large scale networks, for example by parallel processing.

Original language | English |
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Pages | 1-17 |

Publication status | Published - 2008 |

Event | 36th European Transport Conference, ETC 2008 - Leeuwenhorst Conference Centre, Noordwijkerhout, Netherlands Duration: 6 Oct 2008 → 8 Oct 2008 Conference number: 36 |

### Conference

Conference | 36th European Transport Conference, ETC 2008 |
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Abbreviated title | ETC |

Country | Netherlands |

City | Noordwijkerhout |

Period | 6/10/08 → 8/10/08 |

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## Cite this

Brands, T., van Amelsfort, D. H., & van Berkum, E. C. (2008).

*Optimising Differentiated Tolls on Large Scale Networks, by using an Intellegent Search Algorithm*. 1-17. Paper presented at 36th European Transport Conference, ETC 2008, Noordwijkerhout, Netherlands.