One thing I'd never want to do is be around a bunch of angry slugs. When I used to work at the USDA, I knew plenty of sluggers who went out every morning and afternoon. It's really the most organic solution to traffic: individuals acting in a manner which benefit everyone. Combine promotion of slugs with HOT lanes and you'll end up with a much better traffic system. Only in Washington, of course, would different interest groups lobby for slug rule changes...