"All models are wrong, but some are useful." - George Box I dunno, man. I see something like this... ...And I see a developer telling the city council he shouldn't have to pay for a widened road and two traffic lights because he doesn't expect his mall to succeed. My experience is definitely colored by Los Angeles, where nobody builds as many parking spots as they need and nobody accounts for traffic impacts. After all, LAX still doesn't see why they need a cell phone lot. Why not? Because fuck you, we're LAX. But then people like Duncan Black argue that we're crushing the dreams of minorities and destroying livability for hipsters everywhere by requiring all dwellings in Los Angeles County to have two parking spots off the street and I'm like fuck you well-meaning-yet-ignorant east coast liberal douchebags, I have scrapes on my paint from rosebushes because the goddamn streets are so narrow in Venice that I have to drive on the fucking curb sometimes to get around traffic. I'm sure that happens somewhere. I'm just as certain that if Los Angeles County weren't held to the standards they're held to, the gridlock would be 24-hour instead of 18.ITE numbers also assume that projects will be successful, whereas in the real world many are not. This data, in other words, is based on measuring sites that have more traffic than typical sites.
But the bigger impact is on overbuilt roads and the construction of too much parking.
I agree that standards are useful, but that doesn't mean they're holy. The ITE is as far as I can tell a traffic planners' Bible, even though it is hopelessly outdated. I've spoken to some planners here in Calgary and they've said that parking is always one of the more difficult problems, as the regulations demand more parking than is often really needed. And by the way, LA is such an outlier that it's not really representative. It's too low density to have good walking / transit options, but too high density to make room for highways.
2nd densest CSA in the USA, yo I would say that any modeling that has to disregard Los Angeles is useless. As I understand it, Los Angeles is Los Angeles primarily because it didn't fully participate in the highway revolts; I know the proposed map of seattle is a nightmare on wax. By not putting all the roads in, Seattle stayed livable. Los Angeles went the other way. Nonetheless, it's one outcome of a common core of development and hardly unique. It's too low density to have good walking / transit options, but too high density to make room for highways.