Auckland Transport's cost estimate for upgrading Dominion Rd has ballooned by 40 per cent to $66.3 million.
That compares with $47 million which the council body announced late in 2012, after rethinking a controversial $100 million plan which included 24-hour bus lanes along the full 5km length of the route, with extra room for cyclists as well.
Although there will now be little widening - except to extend bus-lanes along the road's southern section between the Mt Roskill shops and the Southwestern Motorway - transport planners blame the latest cost blow-out on having to buy more properties than expected and design changes to preserve parking in side streets after public consultation.
That is to compensate for lost parking on Dominion Rd at peak times, to make way for an extension of bus lanes through village centres in Mt Eden, Balmoral and Mt Roskill, communications general manager Wally Thomas said.
The new cost estimate was mentioned only in passing in a press release on Friday in which Auckland Transport announced that the upgrade would begin in September, after a joint funding agreement with the Government's Transport Agency, which will pay 53 per cent.
Auckland Transport chairman Lester Levy said improvements to the road would allow up to three million bus passenger trips a year and would upgrade village centres with raised planted median strips.
Footpaths would be transformed with landscaping, decorative paving, seating, bike stands, lighting and pedestrian crossings.
But the press release has irritated commuter cyclists by saying pedallers "have been given their own routes on side streets" parallel to Dominion Rd where traffic is light and exhaust fumes almost non-existent.
That reference is to $6.1 million of safety enhancements such as "traffic-calming" chicanes to be added between now and October to 12km of streets on each side of Dominion Rd, which Auckland Transport says will serve 16 schools and encourage more novice cyclists into the saddle.
Cycle Action Auckland chairwoman Barbara Cuthbert said although the group endorsed the project's goals of improving bus efficiency and enhancing village centres, it was misleading to suggest the project catered for cyclists' needs.
"The back roads linking schools will be good for inexperienced cyclists but they don't cater for commuting, where time and convenience are the priority," she said.
Experienced cyclists would continue to travel in Dominion Rd's narrow bus lanes, rather than use "meandering inconvenient back roads".
Dominion Rd upgrade estimates
(From the Southwestern Motorway to Horopito St)