COMPAS Runs for Autonomous Vehicles Scenarios
Goran Vuk, Danish Road Directorate
The paper aims to compare the OTM (tour based model) and COPMAS (activity based model) runs for three cases of autonomous vehicles
This paper is a first Danish evidence of differences between the results for two traffic models – a tour based model, OTM, and an activity based model, COMPAS. Both models are of a discrete choice type and they cover the Greater Copenhagen – OTM with some 900 zones while COMPAS with 10.000 zones.
OTM has been in use since 1996. The latest major improvement includes a sub-model for choice of time of day. A shift in modelling of person travel demand to an activity based approach has been tried since 2011 through a development of the COMPAS model - COpenhagen Model for Person Activity Scheduling. COMPAS runs in the DaySim software.
The two models were run for three scenarios for autonomous vehicles. We conclude that the tour based and the activity based approaches to modelling of person travel demand result in quite different results. Three clearest evidences for this statement are the following:
• The overall increase in car trips is considerably larger in OTM than in COMPAS, i.e. the effect of changing the carpark to autonomous vehicles is stronger in OTM than in COMPAS.
• Slow modes contribute most to the new car trips in OTM runs. However, in COMPAS it is the public transport trips that shift largely to autonomous vehicles.
• The very short trips, i.e. walk, do not change to car trips in the COMPAS scenario runs. Actually, for the Home-Work activity the walk trips increase alongside the car trips. Opposite to that, in all OTM runs the walk trips drop, sometimes quite much.
COMPAS runs also show that:
• The average trip length for autonomous vehicles is somewhat shorter than car trips. Especially modal shift of bicycle mode contributes to this conclusion.
• Car occupancy drops from 1.46 persons/trip in the base run to 1.42 persons/trip in the runs for autonomous vehicles.
• Four new modes were introduced in COMPAS relative to the OTM model: Bicycle-PT-Walk, Bicycle-PT-Bicycle, Bicycle on PT, and Walk-PT-Bicycle. The scenario runs show that introduction of autonomous vehicles changes only marginally the combined trips where non-car modes are included, i.e. the travelers who have arranged their working days in such a way that involves combination of non-car modes do not experience a great potential in switching to autonomous vehicles.
Association for European Transport