Raybo, One year ago today I was coincidentally confronting the same question. I was tentatively planning on cycling from a family cabin in Westmoreland County, VA to Williamsburg (N>S) to meet the Adventure Cycling Tour that I was leading cross country. I called police and other locals with the same question with no definitive answers other than it's legal to cycle across it. Upon arrival at our cabin I decided to scope it out in my truck, less than an hour away.
Zero shoulder. If you got hit you'd fly over a low rail into the Rappahannock far below. I had to concentrate to steer my Toyota between center line and guard rail. I aborted the plan. That said, if you got there at dawn and blasted across.....maybe no problem, but ill advised. I'd say hitch a ride as suggested by jamawani from the pull-out. Upstream, Warsaw to Tappahannock is wider and doable but also busy and scary. Further upstream at Port Royal is safe, but it's a rather busy Rt 17 to get to either of those alternates.
Should you decide to try, There's lots of cool back roads you can link up between Fredericksburg and Whitestone off of Rt 3. Some of Rt 3 is ok. It's busier south of the Norris Bridge.
Last edited by BobG; 03-25-10 at 03:34 AM.