Comprehensive Versus Simplified Models

Many factors play a role in the decision how complex a model should become. The essence of modelling is to produce a replication of a system that is as rich as needed, with a model specification that is as lean as possible. Usually, a desire for a model that is both broad in scope and deep in detail, is detrimental for the modelling process (and result, eventually). In many cases, there are strict limits to model complexity due to constraints in data availability or computer power. This chapter intends to provide a simple guide for practical modelling applications, especially for those situations where there is a pressure for developing simple models, that follow the basic 4-step transport model architecture. We discuss the idea of model complexity including its relation to transport policy, and present strategies to implement the 4-step architecture, depending on the desired level of complexity. These strategies include the modelling of partial systems, integration of submodels and aggregation of agents. © 2014 Elsevier Inc. All rights reserved.