Google API Distance Matrix

Question

I am using the Google API Distance Matrix (mode 'driving') in an optimization program. If I run the program twice a day (e.g. in the morning and in the afternoon), I sometimes get different solutions. Since the Google API Distance Matrix is the only input besides my hard-coded input, I was wondering if the distance requests always return the same standardized distances or if the distances include current traffic etc. as well. Unfortunately I couldn't find anything that specific in the developers documentation.

Can somebody quickly answer my question?

Thanks in advance!

Answer 1

The distance depends on the shortest path, which further depends on the departure time from the origin. From the documentation of Distance API [1]

"Note: If departure time is not specified, choice of route and duration are based on road network and average time-independent traffic conditions. Results for a given request may vary over time due to changes in the road network, updated average traffic conditions, and the distributed nature of the service. Results may also vary between nearly-equivalent routes at any time or frequency."

[1] https://developers.google.com/maps/documentation/javascript/distancematrix

To get consistent results, I would advise specifying the departureTime parameter when calling the API.