The Hataitai bus tunnel in central Wellington will be earthquake-strengthened over the next six months, causing some disruptions to off-peak bus services.
Work on the tunnel, which links the central city to its eastern suburbs, would start in early November, Wellington City councillor Justin Lester said.
While the tunnel itself would likely withstand a reasonably large earthquake, nearby hills and old tunnel entrances could come down and block the bus route, he said.
Bus routes would remain unaffected during peak hours while work was underway, while minor disruptions were expected during off-peak hours.
Some 338 buses use the tunnel every weekday.