30 billion won spent on potholes as rain, heat and winter de-icing compounds take destructive toll

Passengers on a bus staggered after the vehicle hit a pothole, while people waiting on the sidewalk were struck by asphalt debris from cracks on the road at a bus stop in Jongno District in central Seoul on Thursday, as a heat wave sizzled the city.

A black car is about to drive over a pothole in Seoul on July 18. [NEWS1]

Passengers on a bus staggered after the vehicle hit a pothole, while people waiting on the sidewalk were struck by asphalt debris from cracks on the road at a bus stop in Jongno District in central Seoul on Thursday, as a heat wave sizzled the city.

Roads with potholes make for bumpy rides and pose safety hazards to drivers, passengers and pedestrians.

Potholes — in the form of craters in asphalt — are common obstacles drivers face.

According to the Seoul Metropolitan Government, the city patched 8,524 potholes between July and August of 2022, which accounted for 37 percent of yearly repairs.

Potholes increase manyfold during summertime when heavy rain batters the country. Extreme heat and rain can easily deform asphalt.

In August 2020, when seasonal precipitation increased fourfold compared to 2019, the city government mended 13,839 potholes. Monthly repairs in 2020 were three times higher than the previous year.

“Typically, potholes that are 10 centimeters (3.93 inches) deep and 15 centimeters wide are likely to cause secondary accidents,” an official of the Seoul city government’s urban management and design division said. He added that tire damage is the most common type of damage caused when vehicles drive over potholes.

“I was frightened after seeing a car ahead of mine bumping up and down after hitting a pothole at a speed of 60 kilometers an hour at around 3 or 4 a.m. during monsoon season,” said Mr. Kim, a taxi driver with more than three decades of experience.

He explained that a small piece of cracked asphalt from the pothole hit his taxi’s front shield and scratched the glass.

Kim said he “almost hit another car in the next lane after swerving the steering wheel to the right” to avoid the pothole.

A pothole on a road in Seoul [NEWS1]

Although summertime downpours and weighted pressures from vehicles — especially fully loaded trucks and buses — deepen asphalt cracks and potholes, calcium chloride used to melt snow and ice during winter can also cause potholes.

A district office official said they get "bombarded in winter with requests for local public services to put calcium chloride on slippery roads." The official said the number of potholes increases drastically after snow-clearing work.

The official said they have been increasing the salt ratio in de-icing compounds because salt damages road surfaces less than chloride-based substances.

To end the cycle of road damage, the Seoul Metropolitan Government started coating motor roads with concrete-based materials. Concrete is chloride-resistant.

Of 402 bus stations on bus-only median lanes in downtown Seoul, the city has replaced road coverage with concrete-based materials at 105 stops since 2010. The city also promised to upgrade old motor roads by using road-surfacing ingredients for highways, which are more durable and long-lasting than current asphalt roads.

The Seoul Metropolitan Government is the country’s first locality to introduce an AI-based automatic pothole detection system using cameras attached to buses and taxis.

A pedestrian shows a piece of cracked asphalt flicked out from a pothole near a bus stop in central Seoul on Thursday. [KIM SEO-WON]

National spending on patching up potholes has been increasing steadily.

The annual nationwide pothole repair cost increased by around 10 percent, jumping from 29.1 billion won ($21 million) in 2022 to 32.1 billion won last year.

Yet, the central government lacks country-wide standardized measures to prevent and repair potholes. Some provincial and city governments lacking funding support have no other option but to rely on visual inspections to detect specific locations of hollows on the road.

The Anti-Corruption and Civil Rights Commission called for an integrated response system to potholes, judging the problem to be beyond the ability of local governments and individual officials to solve. In April, the commission published a report recommending the government establish a manual for systematic road maintenance and repair through research on the appropriate use of calcium chloride.

“Potholes are inevitable when unexpected downpours cause water leakage under the road surface,” Lee Chang-moo, a professor at Hanyang University’s Department of Urban Planning and Engineering, said. He added that "more detailed road management with increased budgets and dedicated manpower is necessary.”

BY KIM SEO-WON, LEE SOO-JUNG [lee.soojung1@joongang.co.kr]