Road cave-ins

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Context:

• Heavy rainfall has led to incidents of road cave-ins in several cities in the last few days.

What causes road cave-ins?

• The cave-ins or cavities that look like holes in the ground are a product of the incessant rain.

Rainfall:

• Continuous rain leads to overflowing of drains, which can cause leaks in the pipeline.
• When a pipeline leaks and water from the pipeline flows into the layers of earth around it, the earth starts to erode and with time, it gets washed away with the water in the pipeline.
• Eventually, the portion of the road over it collapses because of the erosion. How long this takes, would depend on the size of the pipelines and the leak.

Road digging

• Regular digging of roads leads to cave-ins, too. For instance, roughly 500 points across Kolkata are dug up daily to repair or re-lay electricity, telephone, gas and other utility lines.

Poor drainage:

• Poor drainage and wrong gradient of a road are among the other reasons for frequent cave-ins.
• Both factors lead to waterlogging, which destroys the bituminous surface of the road and leads to water seepage. “Seepage over a prolonged period will weaken the soil under the road and cause cave-ins.”

How can such cave-ins be avoided?

• The integrity of the pipelines would have to be checked.
• Installing a system that checks the flow at the start point and one at the endpoint, would be able to help authorities know that there is a leak. If the leakage is plugged early, the cave-in can be avoided.
• There should be a rule barring utility services from digging up roads at any time they want. Or the road restoration charge should be so high that companies are forced to finish work at one go instead of digging through the year.

Source:

https://indianexpress.com/article/explained/road-cave-in-9425971/