RedPanels

Is there some law of physics that prevents multiple highways to run alongside each other?

it would be extremely impractical...and considering highways intersect with cities, etc. impossible in most cases

you realize that, in a place as dense as a city, there is almost always a non-highway option to get somewhere, right?

1)you changed the argument 2)you would eventually need to use the highway unless you never leave the city

1. No, city streets compete w/ highways within a city 2. Likely, however, then you'd have more space for competing highways

...i don't know of any places where there is ample room for highways to run parallel.

have you never driven between states before? Look left, look right, trees and grass for miles.

not where i live...and there is still the case of when the highway intersects cities, etc.