The Pennyrile Nature Trail (PNT) is a 14-mile footpath that terminates in this state resort park. Recently Backpacker Magazine rated this the most difficult hiking trail in Kentucky. The trail is slightly difficult because it is needlessly twisty and littThe Pennyrile Nature Trail (PNT) is a 14-mile footpath that terminates in this state resort park. Recently Backpacker Magazine rated this the most difficult hiking trail in Kentucky. The trail is slightly difficult because it is needlessly twisty and little-used in parts, but it has none of the steepness, rocky surface, and remoteness found in eastern Kentucky trails. I'd like to come up with a formula for objectively classifying trail difficulty, more specialized than the Yosemite Decimal System, and kinda of like rock crawler and jeeper rankings. For example, a class A trail would be a flat, straight, hard-packed, even camber, well-marked, and always-perfect-weather trail versus a class F which would be a steep, twisty, severe off-camber, rocky, poorly-marked, and crazy weather trail. Here's how I'd like to start. Break each trail in .25 mile segments and measure slope, sinuosity, camber, surface condition, blaze status, and climatography. If a trail was GPSed then the data could be field acquired and a GIS could easily calculate slope, sinuosity and climatography, and field sampling could measure camber, surface condition, and signage. Sub-qualifiers could give classes additional information on quality of infrastructure, fords, and wildlife.