> > There are three basic types of draw bridge. The most common is the kind where one or both sides rise to a near vertical position allowing a tall ship to pass.
> >
> > Sometimes a section of the bridge is on a turntable so that it can rotate 90 degrees allowing ships to pass on both sides.
> >
> > Another type of drawbridge is the vertical lift where a section between two towers rises high enough to allow ships to pass underneath. The Tower Bridge in London is one of those.
> >
> > Without draw bridges, Hollywood car chases would be a lot less interesting.
> > Howard
>
> Tower Bridge fits neatly into the first category. I think a vertical lift might have been a challenging feat for engineers in 1870. Most such bridges were built comfortably into this century.
>
> Also, when I hear the term "drawbridge", I immediately think of a bridge across a moat, protecting a castle from attack, rather than a roadway across a river. I suppose that goes back to school history lessons.
>
> wintermute

I certainly picked the wrong example! It's been a couple of decades since I was in London, and old memories get a little fuzzy after a while. But I'm a little confused. I'm sure there is vertical lift draw bridge across the Thames somewhere in that city, . . . I think. Or maybe I'm thinking of London, Kentucky or London Ontario.