Trail Closures Due to Wet Trails and Freeze-Thaw Cycle Explained

It's that time of the year again when we start to see trail closures to wet trails and freeze-thaw cycles. This article was originally published in February 2021. It's an important trail issue that needs to be revisited. Due to the nature of their design, there are probably more impacts that are caused this time of year with flow-designed trail systems. This article has been updated in December 2024. 

Trail damage due to above-normal wet conditions. 

 

New bikes for Christmas and New Year resolutions to get out and be more active. This time of year we see an increasing number of new mountain bike riders and other outdoor recreational users exploring their local, state, and national parks. This might be their first experience using these public resources and their newfound outdoor activities. 

This post is to help trail users understand why there are trail closures due to wet trails and the freeze-thaw cycle we see this time of year. As an outdoor community, take the time to educate new trail users. It doesn't help to have a negative interaction with someone who is new and doesn't know.

In my local area, we have some fantastic trails! Urban trails in downtown Richmond are part of the James River Park System, and just 25 minutes south of the city, we have an IMBA bronze-level Regional Ride Center at Pocahontas State Park, which hosts over 50 miles of bike trails.

One of the frustrating issues we are seeing now is an increased number of riders still riding when the trails have been closed due to wet weather, or the freeze-thaw cycle. 

Realized that many new riders don't understand the "why" behind the trails being closed this time of year due to wet trails and the freeze-thaw cycle. I am sharing a guest post from Joel, one of our local trail-builders. Joel’s effort to explain the "why" behind trail closures during this time of year was posted to one of the local Facebook pages. At the end of this post, we have provided local resources that communicate the trail status, so you know before you go.

Trail conditions in your region are very subjective due to the surface soil type, drainage profile, and relative rainfall in a given period. Trails on steep contours may drain better due to the gravitational pull of surface and groundwater downward versus trails in a flatter area with greater groundwater retention. 

  

Water will seek dry soil if available, but different soil types present different resistance to movement.  Similar to how electricity moves through materials with less resistance, groundwater moves quicker through soils with less resistance than those that are more porous, and less dense. In dense and saturated soils, (clay, loam) water will move slower than it will through rocky and sandy soils. The primary soil types in the Metro Richmond Virginia area are clay and loam-type soils.

This year the Richmond Metro area experienced record rainfall amounts. This has led to higher groundwater concentrations, raising the water table in our area. You can see this in some trail areas where the ground appears to be leaking water via seeps where water has traveled through voids and seams in the soil substrate. Trail builders encounter these “springs” on trails, and we typically address them via “armoring” techniques – using the rock to harden the surface and other methods to move water off and away from the trail.

Regarding "man-made" trails such as bermed flow style and jump-type trails, these trails are fun to ride and very popular (Park trail counters show this to be true). While not naturally existing on trail surfaces, trail builders design and build berm trails. The trail builder has to build up these features.

Designing and building these features is a bit of art and science within itself. These features usually have shapes and gradients with more surface area than flat ground. The increased surface area and stacked soil lead to more infiltration and moisture retention.  So “built” trails may retain water and moisture while other (natural surface) trails do not.  Heavy precipitation may also result in runoff, leading to erosion and channeling (also not good). 

In the winter, most trees and plants go dormant and don’t provide the added effects of transpiration.  Transpiration- is a process where plants suck up groundwater and hold it or emit it into the atmosphere via humidity expressed from pores in their leaves. Evaporation- from solar radiation is also less impactful during the winter due to colder average temperatures and fewer daylight hours.  So during the winter, plants are not intercepting as much water, allowing more free water into the soil or surfaces.

What is freeze-thaw? 

The water freezes when the temperature drops at night and the soil is saturated. Ice has more volume than water, so it expands in the same space, heaving up the soil and "unpacking" it, referred to as frost heave. When surface temperatures rise above freezing due to solar radiation and/or air temperatures, that ice thaws and turns back to liquid, which is the freeze-thaw situation. 

If you ride or walk on the ground in this state, it turns into a slurry (i.e., a "mess") and destroys its former shape. It’s difficult to predict when trails are safe from freeze-thaw but to avoid damage from freeze-thaw conditions, trail managers will choose to close the trails, and closures may extend well past the last measured precipitation.

The use of trails when in a fragile state will make areas already susceptible to damage even worse and require either longer closures or difficult remediation (fix, re-route, armor, or permanent closure).

As a mountain bike community, we can keep our trails open and in good shape by being aware of poor trail conditions and respecting trail closures. 

Check local trail conditions here:

                                                       

RVA Trail Report on Facebook  RVA Trail Report and on Instagram rvatrailreport

Visit the 

Friends of Pocahontas website at fopsp.org  or text "POCA" to 804-292-2939 to receive automated daily mountain bike trail conditions and trail closures. This text is normally sent at 6:30 a.m. starting in November and 7:30 a.m. starting in March.

RVA MORE website RVA MORE Trail Status.

Now It's Your Turn-

I would like to hear how your local trail systems and trail clubs communicate temporary trail closures due to wet conditions. 

How do they educate new riders about IMBA Rules of the Trail and responsible riding?