The difference between potholes and sinkholes
We are a few weeks into the spring season — a prime time for sinkholes and potholes. According to AAA, pothole damage costs US drivers $3 billion in repair bills each year.
But what is a pothole and how does it form?
A pothole is a hole in the ground which is caused by fluctuations in temperature. Rainwater sinks through cracks in in the road, which softens the surface. As the temperature cycles from above and below freezing, the water expands and contracts. This ends up breaking the pavement, which weakens the surface. As a result of cars going over the weakened asphalt, it begins to break up and crumble. This, in turn, creates the hole.
The low-lying areas will see more of these, because there is more potential for standing water that can work its way underneath the asphalt.
Ken Slack, the Communications Specialist for VDOT's Staunton District, explained how VDOT is always monitoring the roadways to anticipate areas that may already have potholes forming.
"We will have our crews go out on pothole patrol," Ken said. "They will load up the truck with the patching mix and go out there and take care of it."
Our area is also vulnerable to sinkholes, which are a separate phenomenon from potholes. A sinkhole is a very large hole that can go tens of feet deep.
The Shenandoah Valley has a lot of limestone underneath the surface, which is a type of rock especially vulnerable to rain. This is a large part of the prominence of caverns in the Valley, which have led to major tourist destinations for years, but the same processes can also lead to sinkholes.
When you have a lot of rainfall, you might have an underground cave in which the water comes up close to the surface. That, essentially, starts to erode at the roof of that cave, and the erosion leads to a large opening at the surface, which can be several feet deep.
One thing is for certain: always watch what is ahead of you on the roadway, because a pothole could be right in front of you, especially in winter and spring, following cold temperatures and freezing water.