The cracks are on a six-metre stretch at Anna Salai in the heart of the city, parallel to the spot where a bus and a car fell into a crater on Sunday. The stretch was shut to traffic this morning as experts examined the strength of the soil. The road is believed to have weakened because of a metro construction.
On Sunday, several passengers had a narrow escape when their bus fell into the hole.
Giant cranes and tow trucks arrived to pull out the vehicles. Traffic around the area was diverted.
Tamil Nadu Finance Minister D Jayakumar blamed the construction of an underground metro line for the incident.
"It appears to be due to the impact of the metro rail work. It's a lesson for us, Mr Jayakumar said, promising that the stretch would be fixed and traffic would soon resume.
Metro construction authorities said the soil appeared to have loosened due to drilling.