So far... I've never stopped on a bridge. Oh wait -- I can't say that anymore -- I've done it more than I'll admit... and I've stopped in several places with sighs peppered with no stopping signs in order to get a shot for RTA or another news media outlet I was working for.
Photographers are, by their very nature, a little bit nuts.... Just look at some of the photos in this "Where in North America, Is this" collection -- some of them required a serious bit of personal risk to obtain....
I don't plan to stop on the Hoover Dam Bridge for a shot -- and I sure as heck don't recommend climbing around that gorge for a shot -- this is a very dangerous canyon area!