OsmSharp/GTFS — pull request #11 by ericpanorel (2014-11-19 22:33:28+00:00)
Title: agency_id is not required in agency and routes file

Went to validate a GTFS feed and failed. I checked the latest specs in Google page. Looks like the field agency_id is optional for both routes.txt and agency.txt

https://developers.google.com/transit/gtfs/reference#agency_fields

https://developers.google.com/transit/gtfs/reference#routes_fields