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GTFS to Linked Connections

Transforms a GTFS file towards a directed acyclic graph of "connections".

A connection is the combination of a departure and its successive arrival of the same trip. Our goal is to retrieve a list of connections that is sorted by departure time, better known as a Directed Acyclic Graph. This way, routeplanning algorithms can be performed.

Install it

npm install -g gtfs2lc

Use it

First, unzip your GTFS file to a place on your disk using e.g., unzip gtfs.zip -d /tmp

Now, we need to make sure that a couple of files are ordered in a specific fashion, not required by the GTFS spec:

  • stop_times.txt must be ordered by trip_id and stop_sequence. Mind that the number of the columns are also not standardized by GTFS and you might need to tweak the sort command in this repo.
  • calendar.txt must be ordered by service_id.
  • calendar_dates.txt must be ordered by service_id.

We've enclosed a bash script which ensures this for you. It isn't perfect however and may not return the desired result. You can run this bash script using gtfs2lc-sort $pathname.

If you've ensured this, you can use this tool on the command line as follows:

gtfs2lc /path/to/extracted/gtfs -f csv --startDate 20151101  -e 20160101

You also can load the data into mongodb in extended json-ld format as follows:

gtfs2lc /path/to/extracted/gtfs -f mongold -b baseUris.json | mongoimport -c myconnections

Mind that only MongoDB starting version 2.6 is supported.

For more options, check gtfs2lc --help

Enrichment step

The output data can automatically be enriched with this tool when adding the -r or --enrich option. This will add additional stop information that is available in stops.txt like stop name, platform code, station, longitude and latitude. The station information is retrieved from the iRail API, and will emit information like station name, country, longitude and latitude. Next to that, each station will be linked with a LinkedGeoData node (if a corresponding Station node can be found).

Currently, this enrichment step only works optimally for Belgian railway data, because the iRail API is used. When this enrichment step is done for data from other countries, the station information will not be generated.

How it works (for contributors)

We convert stop_times.txt to a stream of connection rules. These rules need a certain explanation about on which days they are running, which can be retrieved using the trip_id in the connection rules stream.

At the same time, we process calendar_dates.txt and calendar.txt towards a binary format. It will contain a 1 for the number of days from a start date for which the service id is true.

In the final step, the connection rules are expanded towards connections by joining the days, service ids and rules.

Not yet implemented:

At this moment we've only implemented a conversion from the Stop Times to connections. However, in future work we will also implement a system for describing trips and routes, a system for transit stops and a system for transfers.

Furthermore, also frequencies.txt is not supported at this time. We hope to support this in the future though.

Authors

Pieter Colpaert - [email protected]