Directions to the University of Maryland at College Park, the Physics Department, and the High Energy Physics Group is provided here. If you need additional assistance, please send email to drew@physics.umd.edu.
To get to College Park from BWI, you head west on 195 (there's only one way to go on 195 anyway) to Route 95 South towards Washington, D.C. The red highway which encircles the city is called the "Washington Beltway". It's about 20 or 25 miles from BWI on 95S.
Once you get near the Beltway, you will have to find your way to Route 1 South. The map shows that you have to exit, head east for a bit, then get off at Route 1. As you leave 95, the exit signs point you to either east (95) or west (495). Take the west exit (right lane), but as soon as the road bifurcates, get into the left lane and follow the signs to "Route 1 South College Park". When you get to the Route1 exit, take south. In the map, the blue square labeled "1" is where you need to go.
