Data on Queue Throughput/Footfall of People in Public Buildings

As I am planning to renew my passport in the near future, I will need to send post securely. (Some activities are more awkward to decentralise into homes.)

I need to answer the question: When is the queue shortest at the post office?

Many public buildings will log door entries, appointment times, number of kiosks open, transaction times, and/or ticketing systems. If I had this data, I could create an app to estimate how long I would have to wait.

Advantage to public sector: Increase efficiency & client satisfaction

It's just like checking highway traffic. A very familiar procedure for the average citizen.

A live system, or even future schedules, would add value to historical data sets.