Absolute carnage is expected on main roads into St Albans city centre, as businesses and motorists brace themselves for a fortnight of grid-locked traffic, while a gas leak is repaired.
Motorists are being warned of severe delays while National Grid engineers work in St Stephen's Hill from Monday.
Warning signs appeared outside St Albans Abbey Station, St Stephen’s Hill and on the King Harry Lane roundabout two weeks ago, and businesses in Holywell Hill said they were preparing themselves for two weeks of chaos.
Richard Cohen, owner of Holywell Hill jewellery shop, Eternity said: "It is going to be absolutely carnage."
He explained: "It is going to be chaos - absolutely carnage.
"I have lots of customers that come from out of town and I have thought about recommending them not to come in at all.
"Traffic here has always been an issue and it doesn’t help at a time when retailers are already taking a hammering."
Temporary traffic lights will be put in place at the junction of St Stephen’s Hill, Griffiths Way and Westminster Court.
Tingting Hung, owner of Con Mi Go fashion store said this was the last straw as Holywell Hill businesses were already being crippled by a rise in business rates and expensive car parks.
She explained: "Two weeks is far too long. It is going to be terrible here.
"Business rates are so high that we have many empty shops on Holywell Hill as it is. We are already suffering, without having two weeks of road works, which will see our business suffer even more.
"Our customers say they have problems finding car parking places because of the time restrictions and high prices - this is just going to make it even worse."
Paul Hargreaves, Mail Boxes Etc store manager, said he hoped the works would be completed as soon as possible.
He said: "This month we have had a lack of footfall.
"We already have problems with customers complaining about where to park on Holywell Hill because it is a one hour limit. With the parking charges and business rates going up, this really doesn’t help.
"Let’s just hope the work will be completed within the expected two weeks and as soon as possible."
Sarah Wilcox, from National Grid said works were essential to stop the leak.
She said: "It is essential that the gas leak is fixed as soon as we can and we have been monitoring it very carefully for some time now. This is at a time when we thought it would be the best time for less inconvenience to everybody.
"It is expected to last for 14 days because we need to allow time to actually identify the location of the gas escape. If we are able to get it done quicker, that is what we will do.
"We would advise people to leave extra time for their journeys and if possible, to travel outside of peak times.
"The works will take place during half term, which we will hope will minimise disruption and impact to the community and traffic flow."