It's spring in Colorado, which means rockslides are more likely to take place, creating a hazard to watch out for on Colorado's roads and trails.
It's important to note that rockslides can be a risk during any season. That being said, spring conditions can make them more likely during this time of the year.
During the spring, Colorado's temperature swings are pretty drastic. This can result in a freeze-thaw cycle during which moisture can drip down into gaps in and around rocks. As this moisture freezes again and then thaws, it expands, which can result in pushing rocks away from spots they've been tightly tucked during the colder months. Heavy rainfall and snowmelt can have a similar effect, causing the erosion of earth that may be keeping rocks in place. This can amplify this hazard during springtime storms.
When one rock falls, it can result in a cascading effect, knocking other rocks loose as it moves and falls down the mountain. As rocks shift, a full rockslide can occur, which basically means a large number of rocks shifting quickly downslope. This can be a major hazard for anyone on or below the slope, including those on some at-risk sections of roads.
An article from Vail Daily reports that there are 750 sites around the state regularly monitored by the Colorado Department of Transportation due to rockfall risk. Rockfall mitigation efforts take place, but it can be impossible to stop all rockfalls as they are very sporadic and unpredictable.
As a general rule of thumb for drivers, one rock on the road means more may be coming, especially if that rock on the road looks like it landed there recently. Use extreme caution in sections of road where this is the case and if one rock is spotted actively falling, avoid driving through that area until it is clear other rocks are not following it.
Debris flows can also occur during this time, especially during periods of heavy rainfall. Never drive through a debris flow.
Find additional tips about avoid rockfall risk on the Colorado Emergency Management website.
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