If you are going the Nats Ballpark from the South (Virginia) be aware that DC Police have put speed cameras on I-395 in DC (right after you cross the 14th Street Bridge) The speed limit drops to 40 mph on the Interstate. Someone told me that got a $125.00 speeding ticket for doing 53 mph in a 40 mph zone on the Interstate near the ballpark. I got a ticket from a camera on M Street seems I was doing 33 in a 25 mph. I don’t know how I was able to go that fast with the traffic.

From an Article from Dr Gridlock in the Washington post.

The new camera locations are all over the District … the location that might get particular attention from drivers is the Southwest Freeway (Interstate 395) around Exit 4, on both sides of the highway.

Drivers who speed get very upset when the District places cameras along highways where they think the speed limits are too low. Near Exit 4, which is in the vicinity of Maine Avenue SW east of the 14th Street Bridge, the speed limit is 40 mph.

... the District’s doesn’t set a buffer speed between the legal limit and the speed for a citation