Single track network. It has a couple of jumps, a few planks to ride, some rooty sections and not much elevation change.
Turn east off the 55 on kitt park, then hang a right on Louis Stephens, then keep going until you see some volley ball courts on the west side of the road. Take that entrance, and park at the research triangle park mountain bike trailhead.
http://www.singletracks.com/item.php?c=1&i=7707