Major roadworks in Springfield Road, Grantham, which were due to take nine weeks to complete have been extended.
Lincolnshire County Council is blaming a rogue gas main wrapped around BT cabling for the hold-up.
A spokesman for the county council said the issue has delayed work and will set the schedule back.
The local authority is pushing the National Grid to carry out the necessary work as swiftly as possible but it is resigned to losing time.
Adam Round, senior engineer at the county council, said:“When we started excavating the road we discovered that a gas pipe was wrapped around a BT phone cable.
“We need the National Grid to safely reroute the pipe and until this is done, we cannot complete the works.
“It’s disappointing that we have encountered this problem but we will do everything possible to keep delays to a minimum.
“With Springfield Road being such an important route through the town, we will temporarily re-open it over the 7th and 8th of September to make sure it does not cause disruption to the Festival of Speed and the visit of the Mallard.”
The extensive work taking place in busy Springfield Road was originally scheduled for completion by September 6.