DC Beltway on a Saturday?

81/17/95 works good for me. Short stretch of construction on 17 is a nuisance for now but not a major problem.

If somebody has issues driving thru Leesburg any time of the day, any day of the week, I suggest that they totally avoid 270-495 around DC.
and the worst part of I-95 is the section from Fredericksburg North to the beltway which should be avoided at all costs.
But any route can develop problems any time any day. My friend who routinely goes from Richmond to North of Frederick always drives the beltway. One time he tried "my" route 15/17 and said it took him several hours extra, which didn't make sense to me. Upon further review, he had made this trip at the time they were looking for the beltway sniper and all roads were clogged everywhere. Additionally he usually makes the trip North after work on a Friday, so things can be a mess anywhere.
My experience with these routes has been trips twice a month for 16 years. 99.9% of the time I have had no issues.
bumpy

I will never do 15 South from Frederick through Leesburg on a Saturday ever again....getting too built up for the 2 lane stretch of road to handle the traffic and all the locals are out shopping / taking kids to soccer games and whatnot.

270 / 495 is USUALLY not bad at all. Just keep an eye / ear out for traffic reports for any accidents. Saturday through that stretch can still have what seems like "rush hour" traffic just from the the locals out shopping / kids activities traffic, just like the Leesburg area, but not quite as bad IMO.

Now, going to Williamsburg, specifically; I'd suggest that when you factor all of this together, you may "adjust" a little more.
Even once you get to DC itself and start heading down 95 (assuming that the plan by the comments made so far), the be prepared....95 South can get way stupid on traffic for no apparent reason. The last 3 trips (we go from RT15 @ PA line down to W-burg at least twice a year) on that rout have been 1 to 2 hours extra time added for traffic sitting / crawling on 95 in that stretch. Every trip was a "light traffic" time of day, not rush hour, too. Should be an under 4hr trip for us and it has taken up to 7. Accidents aren't even needed - just some whim of certain driver to brake check or a guy changing a tire on the side of the road and you get a back-up for miles.

It may all be perfectly fine and you'll breeze through the area never dipping bellow normal highway speed....but if potential for those slow downs bug you enough, you might want to try avoiding the whole area.

One trip I did 301 / 17 and, while it was slow going, it didn't make me want to rip the steering wheel out and throw at someone in frustration nearly as bad as sitting parked on 95 at 7 AM one Sunday morning...and I got there in like 5hrs.
I also generally find that Baltimore traffic is a lot less likely for those non-rush hour random backups.

Thanks for the replies. We'll be driving south on Rt 15 through Harrisburg on our way to Williamsburg, Va. No worries about Baltimore.
I get nervous but not paranoid in heavy Interstate traffic. All in all I'll go the Beltway route going down but may try I81 on the return.

don't forget the detour around Baltimore...no propane in Fort McHenry Tunnel on I-95. use I-695 and cross using the FSK bridge.

as for your question about the beltway and I-270...the earlier the better. The DMV (DC Metro Vicinity) is ALWAYS busy. the earlier you can roll through the better off you are. but you shouldn't have any troubles on a Saturday.

I am coming out of Western MD. when i am south bound i use I-81 to US 17 and pick up I-95 in Fredericksburg, VA. its a pretty drive and keeps you out of the worst of the traffic.

If you're generally comfortable driving on the interstates, I wouldn't go out of the way to avoid the DC Beltway. You might pick a bad day, but it's mostly not too bad outside of weekday rush hours, and your route isn't all that lengthy.

twice a month I drive the Frederick, MD, to Richmond, VA, route and 99.99% of the time I take 15/17 to I-95 at Fredericksburg, I have never taken 234. what is your final destination. I-95 North of fredericksburg can be a mess any day-any time.
bumpy

I'll second Bruce's opinion.

No problem

Bruce