Workers were building a ramp to rescue a 74-year-old male truck driver trapped in a gigantic sinkhole in Saitama, north of Tokyo.

The critical 72-hour survival window passed on January 31.

The ramp will facilitate the entry of heavy machinery in the sinkhole with a diameter of about 40 meters, but several more days are likely needed to reinforce it with materials like lime.

The accident occurred on the morning of January 28, when a 10-meter-deep sinkhole opened on a road, and a truck with the driver fell into it.

A second hole appeared the following day, and the two sinkholes later got combined.

The fire department said the depth now stands at around 15 meters, and about 8 meters of rubble has filled it.

In response to the incident, the Tokyo Metropolitan Government plans to visually inspect the inside of large sewer pipes with a diameter of 2 meters or more that are highly susceptible to corrosion from gases and other factors.