The natural freeze-thaw process is starting to make a noticeable impact with trail surface distortion on our local trails.

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

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.

Tennessee Trails

Trails in Tennessee experience the freeze-thaw process between December and March.  A number of factors play into how susceptible a trail is to the freeze-thaw process, including the amount of precipitation, the ability for the trail drain, soil type, and elevation.  Due to these varying factors, one trail system may experience freeze-thaw when another trail system only ten miles away may be safe to use.

Please be patient and please stay off of the trails until the ground fully thaws.  If you just have to ride then please plan accordingly so that you can complete your ride before the temperatures rise and the trail start thawing out.

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.