VACANCY INTERNSHIP PROJECT We are looking for students interested in carrying out their internship project at DAT.Mobility
Development of a tour based gravity model Problem description There is a large gap between traditional gravity based transport demand models on the one hand and state of the art agent based demand models on the other side. The agent based models are more accurate for two reasons. Firstly, agent based demand models describe complete tours (trip chains starting and ending at home) instead of single trips and are therefore able to take into account spatial and temporal interactions between trips. Secondly, agent based demand models work at the level of individual persons and/or households instead of groups of persons per area, which enables them to also take into account specific person/household characteristics and interactions within the household (i.e.: if one household member uses a car, it is not available for the other members of the household). However, traditional gravity models have some mathematical properties that are favorable in light of strategic transport model applications. Because in such applications, model outputs of different scenarios (e.g. sets of policy measures) are compared, the aim is to single-out differences only caused by or related to the different scenario inputs. Hence, differences caused by random variables (e.g. due to stochastic processes in the model) or because the model output does not (sufficiently) represent a stable system state should be negligible or non-existent. Outcomes from agent based models are subject to both effects: they employ stochastic processes and do not adhere to some specified stable system state, whereas outcomes from gravity models are deterministic and guaranteed to adhere to conditions of maximum entropy, which means that when comparing model outputs of different gravity model runs, all differences are related to differences in model inputs.
Internship / Master thesis assignment The goal of this research is to combine (some of) the accuracy of agent based strategic transport demand models with the favorable mathematical properties of gravity-based transport demand models. To do so we aim to extend the gravity model such that it a) supports whole tours; and b) add a secondary destination module to the gravity model. From a methodological and algorithmic point of view, how these extensions could be implemented has already been drafted by DAT.Mobility and Goudappel Coffeng; the students is asked to translate this draft into a fully operational prototype, determine its mathematical and practical properties and, if time allows, showcase it on one of the larger strategic transport models developed by Goudappel Coffeng.
Research group DAT.Mobility Deventer Daily supervisors: Ir. Luuk Brederode (DAT.Mobility, Delft University of Technology) / Mark Pots Msc. (DAT.Mobility) When interested in this internship or Masters thesis assignment on adding attraction constraints to agent based modelling, please contact Ir. Luuk Brederode (lbrederode@DAT.nl, +31 (0) 627369830).