Tucked in the side of Conococheague Mountain, Big Spring State Forest Picnic Area is a quaint picnic and hiking area. A short loop trail leads to a partially completed railroad tunnel with historic interpretation at the trailhead. The park also provides access to the Iron Horse Trail for day and overnight hiking. The park takes its name from nearby Big Spring, whose waters form the scenic Shermans Creek.
I just hiked both sections south and north of PA274, The southern section is wet and muddy with water on the trail; it will take weeks of dry, sunny weather to dry the trail and make it reasonable. i dont recommend hiking on it. If dry it would be a nice trail. The northern section from Byrne Rd to Big Spring State Park parking is much more manageable but is somewhat overgrown in spots. This section primary follows an old rail-bed that at times is more elevated above the existing terrain. The short trail to the tunnel is not an issue--easily handled.
The Iron Horse Trail is a 10 mile loop trail that is marked using red blazes. The best place to start the trail is at the Big Spring State Forest Picnic Area on route PA 274. The trail is fairly well marked but there were a couple of times I had to pull out my map to figure out where the trail was supposed to be. It is called the Iron Horse Trail since it uses the same routes used by the lumber company railroad lines. I gave it three stars since there wasn't a whole lot to see on this trail.
This is an easy and enjoyable little hike with a an unfinished railroad tunnel as the focal point. Big Springs Park is a lovely place to picnic and spend the day.