Grenville Phillips Speaks – The Birth of a Pothole
After an asphalt pavement has been laid for about a decade, it is normal for rectangular shaped cracks to appear on the surface. These cracks can be economically sealed to prevent further damage to the pavement.
Sometimes, a road is not designed for the actual amount of traffic, and the pavement can crack from overuse or fatigue. These cracks can be straight cracks in line with the road, or shaped like the skin-pattern of alligators. These cracks can also be economically sealed to prevent further damage.
If these cracks are not sealed, then when the wheels of vehicles go over the cracks, they can force powder sized particles out of the underlying base through the cracks, which appear as powder on the surface. This signals that a pothole is in gestation. If the embryonic pothole is not aborted by sealing the cracks, the road will give birth to a pothole.
Sometimes, small areas of the base layer, on which the asphalt layer is installed, is not compacted sufficiently. The asphalt layer may depress or settle in that small area and develop a pattern of alligator-skin type cracks. This is different from the fatigue cracks, which also have an alligator-skin pattern, but no settlement.
Sealing these settlement cracks is not effective. The cracked asphalt should be removed, the weak base material should be compacted, and the cracked asphalt replaced with new. If the weak base is not compacted, the pothole will reappear – like magic. Only it is not magic. It is simply the consequences of a badly repaired pothole.
There are several other reasons why an asphalt layer cracks and weakens. But we seem disinterested in such matters. We are a caring people. We cherish our pregnant roads, and joyously celebrate each new birth. When we nurse, or drive over the pothole, we cause it to grow from a juvenile, to an adult crater.
Why don’t we seal the cracks to abort the potholes? Why don’t we properly repair potholes that result from base failure? The answer appears to be political.
Before a general or by election, the government normally hurriedly patches potholes very badly. These political patches are known to only bring temporary relief. They do not last long, and only guarantee that the pothole will get worse after the election.
The problem is that this time, these political patches are still being done, even after the election is over. I understand the need to keep unskilled persons employed during this time. However, why not simply train them to seal cracks, and permanently repair potholes? The answer to that fundamental question, is blowing in the wind.