Workmen are still exploring the cause of a sinkhole that has opened up under a main road in central Watford.
Specialists from Affinity Water have been called in to examine the site after water was found under St Johns Road.
Hertfordshire Constabulary has dug up the road by the junction with Clarendon Road after large cracks appeared in the tarmac over the last few weeks.
The road has been closed while the investigation continues. The council has said it hopes it will be reopened in time for the weekend.