I am having latitudinal and longitudinal position of around 500,000 bridges and I want the elevation of those bridges using the latitude and longitude coordinates of this bridges. I wrote a script in c# to parse elevation for all the 500000 bridges using the elevation API from the google. I generated google key with my account. Also, I enabled the billing for this account , but after few 100 request, I get an error
We're sorry...
... but your computer or network may be sending automated queries. To protect our users, we can't process your request right now.
See Google Help for more information.
I read the google api limit usage and it says that I can make upto 100000 request a day with billing enabled.
How to parse the elevation for 100000 bridges in a day?
You have hit a TOS issue..10 e to be exact:
No mass downloading. You will not use the Service in a manner that gives you or a third party access to mass downloads or bulk feeds of any Content. For example, you are not permitted to offer a batch geocoding service that uses Content contained in the Maps API(s)
https://developers.google.com/maps/terms?hl=en