Wellington's cable car upgrade not going to be finished on time or on budget

Wellingtonians will have to wait two weeks longer than expected for the city's iconic cable cars to be up and running after a $3million upgrade hit delays.

Daniel Faitaua gets a Wellington history lesson as the windy city celebrates 150 years as our capital city. Source: 1 NEWS

Wellington Cable Car Limited originally projected the upgrade would take eight weeks to complete, but that timeframe has now been stretched to ten weeks.

The cable cars now won't be running until August 15.

The delay means the project will cost more than its $3million budget, but Wellington Cable Car Limited chief executive officer Simon Fleisher couldn't say how much more.

"I can't put an exact figure on it compared to original budget but it's a small increase," he said.

The cost will come from additional labour and the need to continue running replacement buses for the extra two weeks.

The delay came after the company found rust "over and above what we anticipated" on the body and window frames of the cable cars.

"We have to treat the rust, grind it out and re-coat," said Mr Fleisher.

Mr Fleisher said the rust did not pose a safety threat to the cable cars but if left untreated it would "eventually have a an effect on the structural safety".

"It's like anything, if you deal with it at the right time it's perfectly safe. We want to make sure the structure under the paint is in good condition," he said.