Transit Network Coding

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Transit projects are more complicated than roadway projects. Instead of changing the standard roadway network, transit project cards make changes to the standard transit network. The standard transit network is stored in a 'GTFS-like' format, which follows the general format and file structures of the GTFS, but with extra attributes that link transit to the underlying model roadway network, such as model_node_id.

The table below shows typical transit project types and associated example project cards.

Category	Use Case	Project Card Creation Instructions	Example Project Card
Transit Service Property Change	When changing transit service properties, such as headway, routing pattern, or transit stop properties, such as allow/prohibit boarding/alighting.	To modify headway, identify trip_id and direction_id of the service, then set the headway_secs (headway in seconds) to desired value. To modify routing pattern, identify route_id and direction_id of the service, then list out updated routing node sequence in order, following the CUBE convention, where positive node number indicates transit stops while negative number represent non-stop nodes. To restrict or allow boardings/alighting on a subset of transit stops, list out model_node_id for the restricted/allowed nodes under the corresponding property section.	12_18_21_T12_123_22_SFMTA_376_s824.yml ac-transit-route-06-edits.yml
Add Transit	When adding new transit services, such as new route or trips.	If the new transit service being added has a dedicated right-of-way and does not have existing links in the roadway network, add the underlying roadway link through a roadway project card under the 'Add New Roadway' category. (See example: Sonoma_Marin_Area_Rail_Transit_add_rail_link.yml) Add a new transit service by using a .wrangler project card. A .wrangler project card can be thought of as a Python script. Network Wrangler will execute the Python statements stored in the .wrangler project card, performing changes to the standard transit network, which is stored in a dictionary of Pandas DataFrames. Each GTFS file can be accessed through self.feed.<GTFS_filename>. Carefully handle associated information related to the newly added service. For example, when adding a new transit route, corresponding trips, stops, stop_times, shapes and frequency should be specified.	Sonoma_Marin_Area_Rail_Transit_add_rail_link.yml Sonoma_Marin_Area_Rail_Transit.wrangler year_2030_samtrans_express_2.wrangler