Transportation Modeling

There are two talks scheduled for this breakout session:

Developing the ActivitySim Open Platform for Travel Demand Modeling with Ben Stabler, Director of Model Development, RSG

ActivitySim is an open platform for activity-based (AB) travel demand modeling. It emerged from a consortium of Metropolitan Planning Organizations (SANDAG, MTC, ARC, PSRC) and other transportation planning agencies (SFCTA) that wanted to build a shared, open, platform that could be easily adapted to their individual needs, but would share a robust, efficient, and well-maintained common core. It is unlike previous AB model development efforts since it is principally an open software engineering project. The goal is a new community supported framework for advanced travel demand models that will eventually replace the AB modeling tools developed to date. The first generation of AB modeling tools are now mature and in use at various transportation planning agencies around the world. These modeling tools succeeded in establishing AB modeling. However, it can be argued that these tools are more prototype than platform. Prototypes typically lack usability, transparency, stability, extensibility, and optimization. Platforms excel at these requirements. The purpose of this presentation is to share the impetus for this collaborative effort, the proposed solution, and provide an update on progress and next steps.

Current Trends and Challenges in Traffic Simulation with Munehiro Fukuda, Computing & Software Systems, University of Washington Bothell

Traditional transport simulators such as EMME/3 have compared highway traffic to fluid dynamics and thus have modeled it mathematically (in most common cases using finite difference methods.) However, this approach encounters a difficulty in modeling microscopic traffic events including traffic lights, constructions, different types of vehicles, and pedestrians. Therefore, recent traffic simulators including TRNASIMS and MATSim focus on micro-simulation that views traffic as a flow of individual entities or agents, (i.e., vehicles and pedestrians, each with a different itinerary). Such micro-simulation has been highlighted as agent-based modes. Agent-based transport simulation describes traffic network as a graph of small links, each with its own attributes such as a different speed limit. The recent research handles dynamic trip plans, signals, and lanes, parking, public transport, freight traffic, etc. On the other hand, simulation of emergent collective group behavior of agents results in two challenges: (1) simulation models must be calibrated with real-world data since the results are no longer verified mathematically and (2) they need substantial computing resources to simulate realistic problems such as metropolitan transport with millions of vehicles. As focusing on MATSim, this talk will discuss what agent-based transport simulation can do and what solutions are considered to address the challenges.