Auckland Transport is creating extra CBD bus lanes in a bid to limit disruption to timetables once it starts digging up roads for the $2.5 billion underground rail extension.
The council organisation has begun marking up 1.2 kilometres of extra lanes into the city centre, ready for when it starts tunnelling a new stormwater main under the eastern side of Albert St in November.
That is a precursor to a big trench to be dug next year along Albert St - a key bus route into downtown Auckland - from Customs St to just west of Wyndham St.
But even the stormwater tunnelling is expected to affect traffic lanes at intersections with Victoria, Swanson and Wellesley streets, so Auckland Transport is moving some bus routes and stops to new locations away from the work.
The new lanes will be designated for round-the-clock exclusive use of buses, bikes and emergency vehicles every day of the week.
They will include long stretches of Victoria St West and Wellesley St West as well as smaller sections of Mayoral Drive, Hobson St, Halsey St and Fanshawe St.
City Rail Link construction manager Chris Bird says the trenching work, which is for two sets of rail lines to be laid in "cut and cover" tunnels to the start of the main deep-bore section of the 3.5-kilometre rail link from Britomart to Mt Eden, will take about three and a half years.
Auckland Mayor Len Brown wants the main work to start in 2018-19, but the Government is holding out against contributing about $1b to the project until 2020 unless stretch targets for rail patronage and job creation look likely to be met in the meantime.
Mr Bird said Auckland Transport would like people who usually drive to the city centre to consider transport alternatives next year, to minimise effects of the rail project on congestion.