Evaluation of Results of an Activity-based Demand Model in Macroscopic Transport Planning Systems
Ehlert, PTV Group
The paper shows how results of an activity-based model can be evaluated and analyzed in a macroscopic transport planning tool.
Activity-based models (ABM) produce a much richer set of outcomes than aggregated demand models. This includes highly detailed data of individual persons which allows household or person attributes to be summarized at any aggregation level. This paper shows how the results can be analyzed and presented in the macroscopic transport model without losing the additional detail in the results.
Based on the activity based demand models developed in the two research projects iZEUS and eMERGE* the requirements for a data model to represent the data in macroscopic transport planning software have been defined. The data model is designed to serve two main purposes:
• to interact with the external ABM in the calculation process, and
• to allow for interactive evaluation and analyses of results.
This paper deals with the second issue, namely the evaluation and analyses of results. The transportation planning tool PTV Visum has been used to establish a prototype version using existing data structures and functionalities within the software.
The general objective of both research projects is an assessment of e-mobility concepts. iZEUS investigates the commercial traffic of specific industry sectors in order to evaluate the potential for using electric vehicles in their daily business. Scenarios defined under different traffic conditions are calculated to determine the state of charge of the batteries over the course of daily tours. The focus in eMERGE is directed towards private transport. More specifically, it is examined how the existing and planned infrastructure of charging stations in future years can promote and further support the use of e-vehicles. Consequently, both projects provide an excellent show case for applications with specific practical questions to be answered.
The data structures in macroscopic modeling tools differ significantly from more microscopic approaches used in activity-based models. Demand models such as the classical 4-step model operate on an aggregated level by dividing the population into person groups with similar characteristics. The results of the demand calculations are represented as number of trips by mode between the traffic zones. Temporal information is usually taken into account by distributions or macro time periods. The exact temporal and spatial information about the start and end of a trip as well as the temporal progression is not maintained in the calculations. Moreover, the trips are not anymore related to daily activities or other constraints relevant for the tours of individuals.
If the more detailed results of activity-based models are integrated in the data structures of the transport model additional possibilities arise for analyses and the display of results in the context of the transport model. It allows, for example, the display of tours of individuals in the network, also in relation to conditions such as traversing a particular road or the use of an activity location during the course of a tour. This means that for such analyses not only the start of the trip is known but also the starting point of the tour. Other options include the analyses of time series data of network elements or activity locations.
The application of the experimental data model in iZEUS and eMERGE has shown that a functionality to analyze the data already exists in macroscopic transport planning software such as Visum. From the practical experience in these projects it can be concluded that the approach taken is valuable to evaluate and represent the outcome on the required level of detail in one single model.
* iZEUS („intelligent Zero Emission Urban System“) is sponsored by the Federal Ministry for Economic Affairs and Energy and by the IKT for e-Mobility. eMERGE („elektromobile Modellregion“) is sponsored by the Federal Ministry of Transport, Building and Urban development.
Association for European Transport