There is a back way to get into the park: If you go down Ox Road (Rte. 123) and cross the Occoquan as suggested above, after 1/2 mile turn right onto Old Bridge Road. Old Bridge turns into Prince William Parkway, & from there you have a dedicated bike path or lane. Continue on PW Parkway and turn left onto Hoadly, then left onto Spriggs, then left onto Dumfries Road (Rte 234). About a 1/4 mile you will see a dirt path which is the rear of the park. Just keep riding straight downhill until you get to the paved main road. If you're on a road bike, be warned that the path leading into the park from that entrance is rocky and rutted in places. Since you can't pay the bike fee from that entrance, just pay it on the way out. I've done this several times, as my mother lives in Triangle and I'm in Lorton.