Work is being carried out by National Grid to replace gas mains at the junction of Codsall Road and Pendeford Avenue in Claregate.
Three-way temporary traffic lights are in use until the end of this month and there is no access to Blackburn Avenue or Knights Avenue from Codsall Road and Pendeford Avenue.
Muhammed Bilal, who runs the Murco Petrol Station on Codsall Road, said people are avoiding the garage while the work is being carried out.
"I am losing a lot of business because of the road works. My sales are down by half and I am worrying about how I am going to pay my bills," he said.
"Before the work started, the forecourt was always full but now people don't want to come here because they have to queue in traffic for ages.
"I am worried they won't ever come back.
"It is not fair on me and it's not fair on businesses or homeowners who live around here."
Dawn Bonser has worked at Evergreen Hairdressers on Pendeford Avenue for 17 years and said the street is notorious for roadworks.
"During my time here I have seen the island dug up plenty of times," she said.
"Our clients are very fed up with the work. It is obstructing the car park and people are finding it very hard to get on and off.
"A lot of our customers are parking further down the street outside people's homes, which is very frustrating, not only for motorists but for the homeowners too. Many of the people who come into the salon have been sat in traffic for so long that they arrive really stressed out and fed up."
National Grid spokesman Jane Taylor said: "This is essential work that we have to do to replace an old gas main. We have been out to speak to local businesses about the work and we have discussed our traders compensation scheme with them.
"Before we started the work in mid-July, we spoke to businesses who might be affected by the work'" she added.
"We are working as quick as we can and are on schedule to complete the job on time."
Councillor Barry Findlay, who represents the Tettenhall Regis Ward of the city, said he hopes the work will be completed before the start of the new school term to help minimise congestion.