The network is a mix of trail types, ranging from relatively smooth access roads to very technical single track. When you first enter the trail network, you will be on the Arundel High School Cross Country Course. If you cross the stream (either over the bridge or, a bit farther down the trails, straight through the stream, you will reach the access road portion. You will know which one the access road is when you get there-it is wide, pretty smooth, and a lighter, more gravelly surface then the cross country course. Once you reach the access road, turn left, and follow it along until you get to the single track. The entrance to the single track will be a right. All the trails are great, though. The cross country course is also excellent technical terrain (roots, rocks, streams, etc). There are even some features: kickers and a small gap jump on the single track.
The address is 1001 Annapolis Rd. Gambrills, MD. For those without smartphones, if you are going south on 97 past Severna park, turn onto Rt 175 west, and continue on until you get to Arundel HS. Once you turn left into the High school, continue straight to the back of the school. Keep right at the junction, and go to the bottom corner parking lots, and park in the corner by the woods. There will be basketball courts on the left. If you can't find this exact spot, there are other entrances to the trails: behind the softball field and behind the rec fields.
http://www.singletracks.com/item.php?c=1&i=8295