We have transit demand – a version of it, anyway. I started with a script that Lisa Zorn developed back in 2012 when she and Alireza Khani worked on the paper Integration of the FAST-TrIPs Person-Based Dynamic Transit Assignment Model, the SF-CHAMP Regional Activity-Based Travel Demand Model, and San Francisco’s Citywide Dynamic Traffic Assignment Model. The script currently does two things: reformats the data, and assigns disaggregated preferred departure and arrival times. In the future, it may combine data from other sources and perform minimal variable synthesis.
Time blocks to time of day
In order to distribute the trips to discrete times from the five aggregate time periods that SF-CHAMP uses [ AM Peak, Midday, PM Peak, Evening, and Early AM ], the script uses cumulative density functions for preferred arrival and departure times derived from observed SFMTA Automated Passenger Counter (APC) boardings and alightings.
Data reformatting
The demand data is then reformatted to the
Dyno-Demand format to be able
to be read by Fast-Trips.
The Dyno-demand format has one mandatory file
(trip_list.txt)
and two optional files [
household.txt
and person.txt ].
One other item of note is that although SF-CHAMP currently models a variety of sub-modes in its trip mode choice model [ e.g., ferry, local-bus, express-bus, commuter-rail, etc ], the team decided that it would be better to let Fast-Trips make the sub-mode selection in the route choice model. Therefore, the transit sub-modes from SF-CHAMP are collapsed in this script to Walk-to-Transit and Drive-to-Transit.
Transit Travel Demand - Take One
If you are interested in reviewing our “first take” of the San Francisco disaggregate transit demand, you can download it here. Please note that this is by no means a finished product and still needs a fair amount of work, as documented in the various GitHub Issues. That said, if you want some demand that is bigger than the test network, here is something you can use in combination with Take-1 of the San Francisco Bay Area Network.