A crack in a drain has created a sinkhole in Melbourne's CBD, exposing pipes and tree roots and stopping traffic.
Collins Street is closed to eastbound traffic but trams are still able to move through.
The sinkhole is about one cubic metre in size.
A City of Melbourne spokesperson said crews were investigating the road surface and had used robot cameras to confirm the issue was caused by a crack in the barrel drain running down Collins Street.
The hole is being repaired and Collins Street is expected to reopen to eastbound traffic tomorrow.
University of Melbourne earthquake scientist Mark Quigley told ABC Radio Melbourne often sinkholes appear due to "leaky infrastructure".
Associate Professor Quigley said a cracked storm drain or water pipe would leak water into the clay, soil and other material under the road and wash it away.
"It's not that obvious to tell if there's a void developing underneath the surface until the road is no longer supported by the soil beneath it," he said.
When there's no longer any support for the surface, such as a road, it sinks — hence the name sinkhole.
Associate Professor Quigley said the Collins Street sinkhole was small and would be filled with gravel and "life will continue".
"What we do to the landscape and what was already there is an interesting field of research," he said.
