The Tunnel Hill Trail in southern Illinois is 56 miles in length, mostly through forest or heavily-treed areas. The right-of-way began in 1872 as the Vincennes (Indiana) and Cairo (Illinois) Railroad, and one of its developers was Civil War general Ambrose Burnside who is best remembered for his facial hair which gave us the term "sideburns," a transposition of his last name. The railroad had a series of owners -- at least seven including some well-known lines such as New York Central, Penn Central, and finally, Norfolk Southern. In 1991, Norfolk Southern gave the majority of the right-of-way to the State of Illinois, and the first segments of the trail were opened in 1998 and completed in 2001, though some additions were later added at each end.
The lowest points on the trail are at each end -- 340 feet above sea level at Karnak on the south and 370 feet at Harrisburg on the north -- with the highest point midway at Tunnel Hill with its elevation of 680 feet. Not much gain in elevation by mountain standards, but high for Illinois and high enough that the builders decided to tunnel through the big hill rather than going over it, and hence the name, and thus there is at maximum a comfortable 2% grade to the tunnel from either end.
For over 50 years, the tunnel had been over 800 feet long, but a collapse in 1929 reduced its length by 300 feet. The photo below shows the current south side entrance with its surrounding tall sandstone walls on each side and you can picture in your mind that there used to be a "roof" over the trail here which has since fallen. You can also see the tunnel exit at the far end. The year "1929" is carved into the top of the concrete entryway indicating when this new entry was built.
Here's the view as I exited the tunnel at the far side as I pedaled north.
I biked the trail on three successive days from three different trailheads, Tunnel Hill Trailhead, the town of Vienna, and the southern terminus at the Barkhausen Wetlands Center near Cypress, Illinois. The next photo is of the trail north of the tunnel, a lovely heavily-wooded area with steep drop-offs on one side or the other, and sometimes both sides.
A lot of dirt had to be moved to build up the grade along much of the trail's length, and there is often water on one side or the other as you bike.
The southern trailhead is the visitor center for the wetlands amenities in the area and has plenty of parking and modern restroom facilities. It also has interesting displays for the Cache River State Natural Area which is Illinois' only cypress and tupelo swamp. Yes, Illinois has a swamp, and in fact it is the northernmost such swamp in the USA. Here's my post about this amazing swamp.
The small town of Vienna has the most elaborate trailhead facilities with a rebuilt station, a visitor center, playground for kids, washrooms, water, etc. It also has this totem pole as a tribute to the Trail of Tears which passed here. The explanatory plaque and a closeup of the totem pole are the next two photos.
There is also a map of the various spurs of the Trail of Tears...
The trail utilizes 23 original trestles, some of which still have their original side walls (with additional railing added above for safety) as seen below. The trestles range in length from 34 to 450 feet in length.
The longest trestle is the Breeden Trestle seen here...
You occasionally see evidence of more blasting along the trail to create the right-of-way back when it was built.
When you start at the Barkhausen Wetlands Center, the first 2.5 miles are on a spur line, and I spotted this grouping of three mile marker signs, all showing 350 miles from wherever the line had started, but each signpost obviously from a different era of the railroad.
This bridge takes the trail over the Cache River near the southern start of the trail at the wetlands visitor center.
As many trails do today, they have some repair stations along the route. This one was at Karnak where the above spur trail meets the main trail and then starts its northward journey.
The Barkhausen Wetlands Visitor Center is near the town of Cypress. Take I-57 exit 30 to state highway 146, then turn right on highway 37. The visitor center is on the left a mile south of Cypress. There are washrooms here.
The Tunnel Hill parking area (which is .2 miles south of the actual tunnel) is off I-24 exit 14 to US highway 45 and go north 6 miles. Turn left on Tunnel Hill Road and the large lot is on the right in a mile. There are also washrooms there.
The Vienna trailhead is in town on highway146, which has exits from both I-57 and I-24. There is plenty of parking, washrooms, playground, and the town has a diner and several fast food places.