The Rachel Carson Trail is 34 miles of yellow-blazed trail from North Park to Harrison Hills Park. It is a rugged undertaking, cutting through suburban areas utilizing whatever space is available. Power line cuts are popular throughways which means that the trail will often climb straight up or down steep hills. The motto of the trailblazers seems to be "Switchbacks are for whimps". It's a primitive trail with no camp sites or trailside amenities.
The trail from Springdale starts by climbing a steep powerline cut and thankfully stays on the hilltop for a while. After coming down off the hill, it's up Riddle Run Road before picking up another power line. The most brutal hill is down to Murry Hill Road and the Sheetz. A 50 degree slope straight down (or up if your traveling south). Someone has tied a steel cable to a tree to help your climb.
The annual Rachel Carson Challenge covers the entire 34 miles in one day. Most don't complete the event.