Group says Onehunga-East Tamaki truck corridor more urgent than Govt's pet road.
Auckland's main business lobby says a freight corridor through the industrial belt from Onehunga to East Tamaki is far more urgent than the Government's $760 million "road of national significance" to Warkworth.
But the Auckland Business Forum has admitted erring in a submission on the extension of the Northern Motorway from Puhoi, for which it says predicted economic benefits are far below what a freight road beside the Manukau Harbour would deliver.
The submission claims incorrectly that there are estimated benefits of $4 to $6 for every $1 which the freight link may cost to build - even though a route has yet to be determined, and a likely price is unknown.
That compares with just 60c to $1.10 which the Transport Agency expects to gain from the motorway extension from the Johnstones Hill toll road tunnels to the northern side of Warkworth.
When questioned by the Herald about the southern freight road estimate, business forum project co-ordinator Tony Garnier said it appeared to be incorrect and would need amending in evidence to a board of inquiry hearing in April into the agency's planning applications for the northern project.
"I think that's probably an error and it's going to have to be corrected when we get in front of them [the board]," he said.
He believed it was based on an estimate of a return of $2.10 to $3.90 in Auckland Transport presentations last year to his group and the National Road Carriers' Association, assuming a longer benefit period and lower discount rate than used for standard project assessments.
Despite that, Mr Garnier said it remained the business forum's "number one project by far" because of difficulties freight carriers had in making motorway connections to and from locations such as the Port of Tauranga's inland port in Neilson St.
He said the forum stood by the rest of its submission, in which it calls for the Northern Motorway extension to be completed by 2020 despite its more modest economic benefits.
Puhoi to Warkworth road of national significance.
* Route: 18.5km from the Johnstones Hill motorway tunnels to just north of Warkworth.
* Cost: $760 million.
* Construction start: 2015 to 2019.
* Completion date: 2020 to 2025.
* Board of inquiry route designation and resource consents hearing: April 7 to April 30, 2014.
Southern freight route:
* Between State Highway 20 at Onehunga and SH1 at East Tamaki.
* Cost: Unknown, but could be anything from $200 million to more than $1 billion.
* Start date: 2016-2017.
* Completion date: 2019-2020.