Potholes

A pothole is a structural failure in a road surface, caused by failure primarily in asphalt pavement due to the presence of water in the underlying soil structure and the presence of traffic passing over the affected area. Introduction of water to the underlying soil structure first weakens the supporting soil. Traffic then fatigues and breaks the poorly supported asphalt surface in the affected area. Continued traffic action ejects both asphalt and the underlying soil material to create a hole in the pavement.

The American Automobile Association estimated in the five years prior to 2016 that 16 million drivers in the United States have suffered damage from potholes to their vehicle including tire punctures, bent wheels, and damaged suspensions with a cost of $3 billion a year. In India, 3,000 people per year are killed in accidents involving potholes. Britain has estimated that the cost of fixing all roads with potholes in the country would cost £12 billion.

According to the US Army Corps of Engineers, pothole formation requires two factors to be present at the same time: water and traffic. Water weakens the soil beneath the pavement while traffic applies the loads that stress the pavement past the breaking point. Potholes form progressively from fatigue of the road surface which can lead to a precursor failure pattern known as crocodile cracking. Eventually, chunks of pavement between the fatigue cracks gradually work loose, and may then be plucked or forced out of the surface by continued wheel loads to create a pothole.

In areas subject to freezing and thawing, frost heaving can damage a pavement and create openings for water to enter. In the Spring, thaw of pavements accelerates this process when the thawing of upper portions of the soil structure in a pavement cannot drain past still-frozen lower layers, thus saturating the supporting soil and weakening it.

Potholes can grow to several feet in width, though they usually only develop to depths of a few inches. If they become large enough, damage to tires, wheels, and vehicle suspensions is liable to occur. Serious road accidents can occur as a direct result, especially on those roads where vehicle speeds are greater.

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Wikipedia