Hertfordshire Council has closed St Johns Road, between Woodford Road and Clarendon Road this morning - and say it could remain shut for up to four days.
The council added: "It is possible that by exposing the hole and then subsequently back-filling, this will cure the problem. A small section will be resurfaced upon completion.
More top news
Two women had to be rushed to hospital after the driver of a 'BMW' mounted the pavement in a hit-and-run crash.
The shocking moment a cyclist was threatened by a driver with a metal baseball has been captured on a video posted online.
Music festivals and big sporting venues put on on “high alert” - one of Britain's most senior anti-terror police officers has revealed.