A street in one of Wellington's busy inner-city suburbs will close for two months, while a $240,000 retaining wall is being built.

Bidwill St - a popular shortcut from Brooklyn Rd to Wallace St in Mount Cook - will be closed to traffic from Wednesday, July 22 and is expected to remain closed until late September.

However, pedestrians will still be able to walk past the construction site and residents will still have access to their homes and be able to park their cars in the street.

Wellington City Council spokeswoman Claire Hinton said they contracted Retaining and Civil Construction to build the retaining wall, after a routine maintenance check identified issues in the road bank.

"Cracks have appeared in the bank beneath the road in recent months. It is thought the subsidence has caused a stormwater main beneath the road to fracture so the piping will also be replaced.

"The $240,000 project is necessary to prevent the collapse of the road."

Significant rain fall from April to June could have contributed to the bank subsiding, but "we cannot say with certainty that this has been the cause", Hinton said.

Diversions would be put in place to redirect traffic along Taranaki St, Webb St and Thompson St, she said. Hinton did not expect any congestion on the alternative route.

"It's a pretty narrow road and with any diversion there is always going to be some extra traffic, but the alternative routes are main roads so hopefully the traffic keeps flowing."

There would be a lot of signage so motorists would know what was happening, she said.