The sinkhole at the Jalan Pudu, Jalan Imbi and Jalan Hang Tuah intersection has been filled with sand to strengthen the base and prevent further soil movement.
Mayor Datuk Seri Ahmad Phesal Talib said about 1,500 cubic metres of sand had been poured into the sinkhole.
“Currently, we are looking at fitting in steel sheet pile to strengthen the soil, a permanent support for the cables and, if feasible, using an open-cut method to build the underpass.
“The exposed underground TNB cables are a very big concern as these service half the city. Since the earth support has weakened, we are using high-tension nylon belt and crane to craddle the cables,” he said.
The sinkhole measured about 20m by 10m.
Ahmad Phesal said City Hall was waiting for a complete report from its consultants before starting remedial work.
“Our priority now is to strengthen the soil and prevent further damage,” he told reporters during a visit to the site.
Contractors working on City Hall’s Pudu Underpass project, he said, had spotted stagnant water on the roof of the underpass during a routine check at 8.30am on Wednesday.
“They began monitoring it and took road measurements every 10 minutes, which showed that it was sinking. Immediate action was taken to clear the area of all traffic and people.
“With the help of police, the area was cleared and cordoned off by 10am and the traffic was diverted to adjacent roads. The road caved in at 10.38am,” he said.
“If there is any (negligence), rest assured I will take action,” he added.
Syabas corporate communications and public affairs general manager Priscilla Alfred said water supply in the affected areas was back to normal.
“Our 600mm steel pipe under the intersection broke at about 1pm after the road collapsed. City Hall has appointed its contractors to carry out temporary repair works on the pipes on Wednesday night,” she said.