It's assuming that population keeps growing exponentially. It isn't.
It's assuming that the Boys Downtown get everything they want, and that all employment 20 years from now will be downtown, and the employees will live in the suburbs and commute downtown instead of growing a brain and solving their problem by finding or creating jobs in the suburbs and exurbs.
Why is everybody a capitalist until some poor slob tries to get out of the rat race by buying himself a job in the 'burbs? No, he has to turn into a socialist and get in line to get on a rationed transit "system" run by policy junkies for their own benefit.
bump
No, it doesnt. It uses Empirical (Statistical) Modeling to estimate the population over the 10-year period.