There is a u-turn in the median at the end of the overpass over Matsonford road which is just north of the overpass over I-76. Coming Southbound it is on your left, right before Exit 16. Troopers will sit here more often during rush hour, however since this area is a choke point, traffic flow here is usually much slower and near the posted 55mph speed limit. You can see any troopers here when you are coming Northbound, as you come around the bend before you drive over I-76. You can see them well in advance before they can clock you. Southbound is not as easy to see and it might be too late by the time you see it.