As part of a project which deals with comprehensive free-flow toll systems for trucks and buses, a multi-
agent based simulation model was developed. This model is used here to discuss the general development 
process for multi-agent based simulations which map real-world situations and whose results are the 
foundation for real-world decisions. It will be demonstrated that developing such models is a demanding 
task, requiring detailed understanding of the relevant reality and meticulous work. In addition findings 
from the model and their implication for planning and installing real world comprehensive truck toll 
systems will be outlined.