Earlier quoted context omitted.
I'm curious how different living next to a highway is to living in a dense urban city though (like NYC) and if it's different why? In either case you have a lot of car traffic (probably closer to your place of residence than people that live close to a highway) Not to mention if you live in a dense urban city then you will spend more time walking directly next to traffic.
Whatever the effect, it's at least getting better. As someone who rides a bike to work every day on urban roads that are usually congested, the recent rise of hybrids, and even just cars with auto start-stop systems, has been a blessing. It used to be that driving next to a line of stopped cars was a nightmare, but now at least half of them have their engines off, if they have an engine at all. Moving an automobile a…
If the terrain is flat, I agree. In hilly cities, not so much.