Google are not transparent about what public transport agencies they use, so it is hard to compare directly, but we publish our data here (get in touch with [email protected] for a full list of agencies)

In benchmarking exercises we sometimes find that we have public transport routes not included in Google

Google therefore may return a slower public transport route as it lacks the data of a faster alternative

The following parameters are all completely configurable using the TravelTime API, but with the Google API they are not, and it isn't clear what the default values are:

Maximum Walking Time - the time allowed to walk from the origin to the first public transport stop/station and from the final stop/station to the destination. Often Google will return a result that requires more than the default Maximum Walking Time for the TravelTime API (15 minutes)

Change Delay - the time penalty (if any) applied when changing from one public transport leg to another

Maximum Changes - the number of changes allowed during the journey

If there is no route available at the arrival / departure time selected, Google will try to return an alternative (such as a journey that is actually the night before), whereas the TravelTime API will simply return an unreachable result

The TravelTime driving model does not take into account live traffic conditions, but instead is modelled around expected congestion at a particular time of the day

When a driving journey starts away from the road network, the TravelTime API applies a time penalty based on how long it would take to walk to the nearest road, based on an average walking speed. Google will snap to the network without a time penalty

Google allows snapping to the road network over a much longer distance (5km vs 1km) which can cause unrealistic results, such as a route allowed to start in an extremely remote location nowhere near a road