Steep but not the steepest

Liverpool Street has been officially crowned the steepest street in Auckland.

Central Auckland’s Liverpool St has been recognised as having the greatest gradient in the city through work undertaken by Auckland Transport, said Don Munro, the agency’s manager of strategic policy.

Mr Munro said this work was carried out to clarify legal issues for approving roads steeper than 12.5 per cent and Liverpool St was identified as the steepest street with a gradient of 24.8 per cent.

Mr Munro explained that gradient is the vertical height of a street horizontally measured as a percentage.

“Comparative street gradients in Auckland are the entrance to Mount Victoria in Devonport at 17.4 per cent and Victoria St outside the Victoria car park at 13.3 per cent,” said Mr Munro.

Liverpool St is trumped by Dunedin’s Baldwin St, recognised in the Guinness Book of World Records as the steepest street in the world with a gradient of 35 per cent.

Mr Munro said roads should preferably be designed and constructed at gradients within the 12.5 per cent limit. “Steeper gradients beyond standard can result in stability and safety issues for vehicles.”

Auckland Transport chief of road services, Andrew Allen said although there had only been one accident on Liverpool St in the past five years, experts agreed that the steeper the road the greater the likelihood of a crash.

“Heavier vehicles tend to have more difficulty with braking on steeper gradients,” said Mr Allen.

Auckland Transport’s cycling manager Kathryn King said steep streets could cause problems for cyclists, but they did not have to avoid them. “Regularly servicing your brakes and maintaining good tread and proper tyre pressure are musts for downhill routes.

“E-bikes take the bite out of the uphill but will need more regular brake servicing,” advised Ms King.

Mr Allen explained that the maintenance of steeper roads was more expensive than roads with lower gradients. “It is a fact that maintenance efforts and costs increase.

“On steeper gradients asphalt surfaces are subject to tar bunching up, often like corrugations in the wheel paths,” said Mr Allen.

Mr Allen explained that heavy vehicles were more likely to cause tar bunching on steep streets. “This leads to far more complex and costly rehabilitation requirements.”

Mr Munro said steep gradients also affected road drainage with steeper roads resulting in faster water flows, which can be difficult to manage and cause damage.

Most pedestrians walking up Liverpool St were observed to be slightly breathless when they finally reached the top of Auckland’s steepest street.