Your best bet for getting around the tremendous mess of traffic in the DC area is to avoid I-95. Take rt 301 south to just north of Richmond. rt 301 is somewhat slow because of shopping centers and traffic lights but there is no problem the traffic is moving and rarely an accident on the road. I-95 is nothing short of a nightmare virtually 18 hours of every day. Avoid 495 beltway around DC which is just as much of a nightmare. You lose about an hour going down 301 but the horrendous mess on I-95 will have you sitting in a stop and go mess, irate drivers and the like until you get to Frederickburg Va which is 50 miles below DC. Whereas 301 is just a casual drive. The bridge at 301 over to virginia will cost you $6 per axle and its a two lane road over the bridge but no problem. Just remember stay away from I-95 and 495 beltway around DC. You will again pick up I-95 at the Flying J just north of Richmond. I have traveled thru this area probably 50 times and the route just get worse all the time. Said to be one of the 6 most conjested areas in the USA.