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According to Terry West, an emeritus professor of engineering geology at Purdue University, urban sinkholes usually begin when the sand and gravel under the pavement erodes due to an underground seepage.

As the soil crumbles, a chasm grows under the road until the pavement collapses. Professor West said the process often takes years, but severe storms like those that have hit New York City in recent weeks can accelerate the decay.

“If too much water is running onto the pavement, it can increase the drag rate,” he said.

Jonathan Bowles, executive director of the Center for the Urban Future, a research institute focused on economic policy, said New York City has made progress in improving its infrastructure in recent years to repair water networks and repair roads, among other measures.

But Mr Bowles said the current pace is not “sufficient” to overhaul something that has long been in disrepair. He said the rate of road renovation is increasing, but the city is lagging behind in structural repairs, such as maintaining and rebuilding the foundations of streets.

“A large part of the basic infrastructure of our streets comes from the first half of the 20th century,” he said. “The city is really playing catch up.”

Mr Bowles said billions of dollars are needed to meet all of the city’s infrastructure needs, from renovating public housing to modernizing subway signals and supporting streets. And these streets weren’t built for the more frequent heavy storms and rains.

“I think extreme damage to our infrastructure, extreme failures are becoming more common,” he said. “This doesn’t mean there will be a sinkhole every month,” he added, but the infrastructure has become “extremely vulnerable.”