The picture you are seeing is the Iron Ore Trail.  The Iron Ore Trail was first created a long time ago and was used for transporting Iron Ore.  After the mines were closed down and the company that used to own Armco Park called Armco (AK Steel) moved, and the land was turned into a park for families to play.

 The Iron Ore Trail is a 5.1-mile-long hike and is rated a moderate trail, with multiple trail heads.