Theres no path on alongside Rosecroft road. There is the wooded path, but there is hardly even a shoulder on Rosecroft
Actually the trail turns into a path (that nobody uses) along the sides of Rosecroft.. and in places the Eagle Nest Trail parallels Rosecroft, it's a level fairly smooth trail safe to run on.. Come down Hogaboom, and turn left or right and there is a trail on the north side of the road, doing the loop back to the visitors center the path goes the entire distance back to Hogaboom (though most everybody chooses to run/walk and bike in the street). Going right the path extends about 3/4 of a mile until it intersects with the wooded trail.. then you can pop back onto Rosecroft, loop around Shipping Point and back out to Rosecroft for the trip back to the visitors center..
There's even a path that Parallels Hogaboom, marked by a tunnel of parallel trees, but 99% of people walk/ run and bike on the road.. I don't remember the last time I've seen somebody actually on the path.
BUT Rosecroft there is LOT less traffic and the speed limit is 35, in addition very few college kids drive there so people will actually slow down and move over and give you room.. I have no fear of running and/or biking on Rosecroft and I've been out there at night fairly often.. it's EXPONENTIALLY safer than running on 5 or Mattappany..
And just to add.. I enjoy running on the wooded trails, a little more concentration is needed because.. well, they're trails.. but there's a lot more STUFF.. turns, switchbacks.. uphills.. downhills.. bridges.. to do. The Western most trail is a lot more runner friendly than the more Easterly part of the trail, but neither is really that bad.