Dynamic, Integrated Model System: Sacramento-Area Application, Volume 2: Network Report (2014)

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25 A p p e n d i x A Starting with DST_FT_module.py, successive sequential steps to run the DynusT–FAST-TrIPs integration model are processed as follows: Step 0: ft_BST.py -> ft_Intermodal.exe Step 1: DynusTx64.exe Step 2: FAST_TrIPs.py -> ft_Assignment.exe -> ft_Simulation.exe If not converged yet, go to Step 1. Else, stop. Step 0: ft_BST.py To initiate the main DynusT–FAST-TrIPs integration model, DST_FT_module starts with the boot-strapping process, ft_BST.py, which first reads veh_sout.dbf as input files and converts it to text file, to make the file reading more efficient in DynusT and FAST-TrIPs. Then, it runs intermodal assign- ment (ft_intermodal.exe) which • Separates auto demand and transit demand (modes 6 and 3, respectively) and writes them down in separate files for DynusT and FAST-TrIPs use; and • Runs an initial intermodal tour assignment (with static auto travel times and printed transit schedule) and splits inter modal tours into transit and auto trip segments, and appends them into the auto and transit demand files. Therefore, after running the python script, demand files are generated for auto (including auto trips and auto part of inter- modal tours) and transit (transit trips and transit part of inter- modal tours), which are used for assignment in DynusT and FAST-TrIPs, respectively. Step 1: DynusTx64.exe The DynusT module mainly assigns and simulates auto demand, including ABM trips, exogenous trips, and auto trip in intermodal trip. For integrating with FAST-TrIPs module, critical transit vehicle arrival information (AltTime_transit .dat) is created. Step 2: FAST_TrIPs.py FAST-TrIPs module consists of three components: transit assignment, passenger simulation, and intermodal assign- ment. These components are designed in separate files (ft_ Assignment.exe, ft_Simulation.exe, and ft_Intermodal.exe) and are executed sequentially as explained below: • Transit Assignment (ft_Assignment.exe) This component assigns passenger trips along the searched transit path, which typically shows boarding and alighting stops, used transit trips (or vehicles), and access and egress times. Transit paths are assigned to transit passengers so that they can be simulated in the next component (passenger simulation). • Passenger Simulation (ft_Simulation.exe) Using the passenger assignment information (ft_passenger. dat) and simulated transit vehicles’ information (AltTime_ transit.dat), passengers are simulated on the transit network from their origin to destination, so that passenger flow on each transit trip (vehicle) is determined. After running this compo- nent, transit-related outputs are generated and dwell times (in TransitDwellTime.dat) are fed back into DynusT module in an iterative process. Convergence of the system is also tested in this component and the result is printed in ft_convergence.dat. • Intermodal Tour Assignment (ft_Intermodal.exe) The intermodal tour assignment is the same function used in ft_BST.py, which assigns intermodal tours to optimal park-and- rides and splits transit and auto segments for the next iteration. The difference is that in this step, the results of simulation (time-dependent travel time and experienced transit vehicle trajectories) are used in the algorithm. In the latest iteration of DynusT–FAST-TrIPs, the intermodal assignment is not required and transit passenger simulation is the last step of the model. DynusT–FAST-TrIPs Integration Model Execution