Once a City Positioning System is deployed, one very interesting usecase that should be on the shortlist is the Quantified Commute.
Through the NYCDataWell Launcher App, a user can register Work and Home locations as well as the timings of the typical workweek schedule.
With enough users, the MTA can really do super-efficient allocation of transportation resources. And with the City Navigation System enabled and powered by the CPS, the City can even do proactive notification and re-routing as illustrated in the NYCDataWell Story when the Dad was automatically notified of a changed bike route when the City's emergency services had to close down a section of Broadway.
The City can even track multi-modal commute patterns based on heuristics (3mph - walking rate; connection times between transfers, may it be subway-to-subway or bus-to-subway; recognize when the commuter is in a car, taxi or biking, etc. etc)
This usecase alone, in our opinion, justifies the installation of a City Positioning System and makes a compelling case for something similar to the DataWell.