In their bid to rescue a 74-year-old man trapped in a sinkhole in Saitama Prefecture, rescue crews are preparing to deploy heavy machinery to stabilize the site.

The disaster occurred at 9:50 a.m. Tuesday in the city of Yashio, when a sinkhole suddenly opened at a busy intersection, swallowing the truck the man was driving. The initial hole measured about 5 meters wide and 10 meters deep, but intermittent cave-ins have since expanded it dramatically.

By noon Thursday, local fire officials said the sinkhole had grown to approximately 40 meters wide and 15 meters deep, according to Jiji Press, complicating rescue efforts.

¡°The collapsed area has expanded several times beyond the original size and grown deeper, making operations significantly more challenging,¡± the city¡¯s fire department said Thursday.

¡°We are taking every precaution to ensure safety while working urgently to locate the missing man.¡±

The driver was last heard responding to rescuers around 1 p.m. Tuesday, but communication was lost after the truck became further buried under soil and debris, according to NHK. Authorities had not been able to reestablish contact as of noon Friday.

Officials have been using drones and ground-penetrating radar to assess the extent of the collapse, but ongoing soil erosion and water accumulation have made the situation even more precarious.

To stabilize the site and facilitate rescue efforts, crews are excavating a 4-meter-wide, 30-meter-long ramp to deploy heavy equipment and clear debris.

Work began Thursday, with officials aiming to reinforce it before allowing machinery to enter. The prefectural government hopes to complete the slope on Friday, using sandbags to control water flow. Authorities are also working to divert rainwater and other inflows to prevent further destabilization.

Meanwhile, Saitama Prefecture has urged approximately 1.2 million residents across 12 municipalities to limit their use of water for nondrinking purposes, including bathing and laundry, to reduce the strain on the water system. In response, Tokyo¡¯s neighboring Adachi Ward is allowing affected residents to use its 23 local bathhouses free of charge.

Transport minister Hiromasa Nakano told reporters at a news conference Friday that the government will consider necessary measures to strengthen the country¡¯s sewer infrastructure, according to Jiji Press.

¡°We will thoroughly review and implement the necessary measures based on the results after the investigation into the cause of the accident,¡± he said.