This photo demonstrates how even foot traffic during the freeze-thaw cycle can impact the trail long after it drys out.

The natural freeze-thaw process is starting to make a noticeable impact with trail surface distortion on our local trails.  In particular the Raccoon Mountain trail network is experiencing the freeze-thaw process.

Between abundant precipitation and very cold temperatures, off road enthusiasts have been largely kept off their bikes for weeks.  After a long cold and wet month many mountain bikers are just itching to ride.  The arrival of warmer weather means that many want to head out on to the trails right away.

Most mountain bikers understand riding a trail when wet and muddy can cause rutting, puddling and other forms of trail degradation.  However, many of these same users don’t understand that trails are at even greater risk during the freeze-thaw process.

This trail has suffered degradation from foot traffic during the free-thaw process.

What is the freeze-thaw process?

During wet winter months, when the trial becomes saturated and temperatures drop, ice forms in soil voids.   Through the night temperatures drop and the freezing process pushes soil grains apart reducing particle cohesion and soil strength and making the soil more erodible.  During the day temperatures increase and the trail surface thaws.

Even though the surface has thawed, the ground is still frozen just below the surface. To make matters worse, the frozen ground prevents precipitation from sinking in any further. This means the thawed layer at the surface is absolutely saturated with water so it is very intolerant of any disturbance. Come riding along and you’ll cut through the thawed layer right down to the frozen ground. The thawed layer will end up with ruts from the tire tracks, which will persist even when the soil dries out.

Local Trails

Chattanooga is currently experiencing the freeze-thaw process. Due to its elevation, the Raccoon Mountain trails are at greater risk to damage associated with use during free-thaw than other local trails.  

Please be patient and please stay off of the trails until the ground fully thaws.  Consider riding at Booker T. Washington State Park, which due to its lower elevation and soil type is less at risk to the free-thaw process.

Precious Resources

Our trails are a precious resource. A little bit of forethought now will mean that they will be in good shape in a few weeks time.