The story changes depending on who is telling it, but the general gist is that a pregnant woman named Maggie was killed in an auto accident on this bridge - I don't know when, but I heard the story when I was a kid, so it was sometime before 1986. Now the bridge is haunted, according to local legend.
Again, the story varies on what you have to do in order to see something, but the most popular version of the story requires you to turn off your car, take the keys out of the ignition, get out of the car, and call out "Maggie, I have your baby."