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Esri / public-transit-tools

Tools for working with GTFS public transit data in ArcGIS
Apache License 2.0
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Enhance Count Trips on Lines to use actual shapes #93

Closed mmorang closed 3 years ago

mmorang commented 6 years ago

Count Trips on Lines currently just generates a straight line between connected stops, ignoring the actual paths the transit vehicles travel, so it isn't great for visualization. Enhance the tool to use shapes.

This will be challenging because shapes are only loosely tied to the stops, and the code would have to have a lot of data validation and checking for invalid shapes. I could theoretically rely on the shape_dist_traveled field in stop_times and use some linear referencing to assume the position of the stop along the shape, but this seems pretty prone to data quality issues. Plus, how to handle corridors served by trips with different shapes?

mmorang commented 5 years ago

See https://community.esri.com/message/799709-re-issues-running-the-generate-gtfs-shapes-with-network-analyst-tool

mmorang commented 5 years ago

Another related enhancement request involves adding the average travel time for each segment.

mmorang commented 3 years ago

This issue will not be addressed, as the BetterBusBuffers tool will be deprecated with the upcoming release of ArcGIS Pro 2.9, which will include the new Calculate Transit Service Frequency tool with equivalent functionality. The new tool unfortunately has the same constraints with regard to line geometry. The new tool will use the geometry present in the LineVariantElements feature class in the Network Analyst public transit data model. This feature class is typically created from GTFS data using the GTFS To Network Dataset Transit Sources tool, and that tool makes straight-line connections between stops.

The root of the issue is really the GTFS specification itself, which maintains only a loose connection between the schedule data and the route line geometry (shapes). I just don't have a good way to safely and consistently use the shapes as the line geometry and also guarantee good connectivity.