Mt Roskill overbridge steeper than harbour bridge

Traffic has started using the last of four vehicle bridges built over the $195 million State Highway 20 motorway extension which is due to open through Mt Roskill in about March next year.

The steep Hayr Rd bridge has been opened to southbound traffic only in the first instance, while work is completed over the next month on a road connection for northbound traffic.

Drivers heading south from the busy Carr Rd roundabout will climb a 9 per cent gradient to a height of 5.5m over the new motorway before descending on a leftward curve to Melrose Rd. That's almost twice as steep as the 5 per cent gradient of the Auckland Harbour Bridge, to which cyclists and pedestrians are battling to gain access.

Those wanting to travel west along Melrose Rd towards Keith Hay Park and Roskill South will then loop back under the new $6 million bridge.

The 160m seven-span structure is the sixth and final bridge to be built by Transport Agency contractors over the new motorway. Four of the bridges are for all road users and two are reserved for pedestrians and cyclists.

But work is continuing on a ground-level bridge on the motorway itself to carry traffic over Oakley Creek at the edge of Keith Hay Park.