The most reliable process for transportation model development is to start with three documents.
- A Statement of Customer Transport Modelling Requirements, which the model must satisfy.
- A Transport Model Functional Specification, specifying the functionality of the transport model that is designed to meet these requirements: this should describe the overall transport model structure, the inputs and outputs, the functions to be included in each module of the transport model and the interfaces with other systems and data (see extracts from those for the Wellington and Auckland Transport Model Functional Specifications). In addition to these extracts, other information included in these specifications related to the adequacy of existing data and the requirements for new surveys and, for Auckland, the appropriate software packages and the interface between the land use and transport models.
- A Transport Model Technical Specification, setting down the detailed work programmes to accomplish the development of the transport model and fully specifying each task. The aim of the Technical Specification is to describe the path to the successful completion of the transport model development, and this transport modelling guidance provides the building blocks for the Transport Model Technical Specification.
Before commencing detailed design it is important to set out some preliminary ideas on the travel, person and household segmentations
that you will use throughout the transport model, and describe any other key decisions on model scope that have already been made. This will inform the design of the data collection exercise and travel surveys
. It is also appropriate to start planning the transport model estimation