I was once walking down Pennsylvania Avenue in Foggy Bottom (George Washington U. area) on my way to see some of the "touristy" stuff when Bush's motorcade drove by at about 150 mph.  About five minutes before it passed me, I could hear the police sirens all the way from Rosslyn, and officers started clearing -- pushing really -- pedestrians from the sidewalks.

Maybe it's a Texas thing.  Texans are, I'm convinced, an entirely different species.  These are people who wear jeans and wool plaid shirts when it's a hundred and twenty degrees outside.  We really should've let it remain an independent country.

Be nice to America. Or we'll bring democracy to your country.

That being said, I haven't heard many people complain about excessive speed (or endangering the public) when these things roar through.  They usually start by temporarily closing off all side streets, then block pedestrians from walking into the street.  Then the motorcade roars through on the cleared streets, and the whole thing moves on.  5-10 minutes is about all it takes.

Not to say that there haven't been incidents though.  There might have been one a few years ago, but I only have a vague recollection of it all.  People who live up in NW DC near the Naval Observatory might have an entirely different take on the whole thing.