We use OpenTripPlanner for translating GTFS in a format to use with this. What type of bridge did you have in mind? What city/services were you looking at?
I opted not to use GTFS as it didn't meet my needs with regards to many things, for example I built a pricing engine/calculator which calculates prices dynamically based on a set of rules, and as a result for train services that are priced based on track distance, I needed to draw the tracks accurate to a few meters per km, so that I can extract the pricing information from there.
When I have time in the near future, I want to write a Node.js script that converts the data that I have to GTFS, fairly trivial but not a priority at this point :)