There may not be a direct metric, but there are a number of mechanisms that municipalities can use to track things:

* use of public transit

* use of roads / traffic measuring

* measuring counts of pedestrians

* anecdotes and actual data about the performance of businesses near offices

* water, electricity, and other utility metrics

* parking tax rates

These are just the ones I can think of off the top of my head, and I am sure there are many others that are not obvious.

Those are just the things off the top of my head.