What does anyone know about how the number of trips generated/attracted to a commercial area changes as development proceeds. The scenario is this: a new retail center has begun to fill in, there is a Wal-Mart, Home Despot, Best Buy, Circuit City, a major grocer, Linens'n'Thing, etc., etc.
Is there a point at which adding new uses does not add traffic. or at least as much traffic as if each use were considered independently, because the customers are already there? This question applies both to the addition of relatively small uses - like say a new restaurant or a new card shop - and to the possible addition of another major retailer, like an REI or LL Bean.
Any thoughts from the transportation planning gurus will be appreciated.