the coastal plain at Mackays Crossing. It then becomes the Transmission Gully Motorway and steeply ascends through mountainous terrain to the Wainui Saddle, before descending through its namesake to Pāuatahanui and bypassing Porirua to the east before reaching the northern suburbs of Wellington, New Zealand's capital city. Immediately after entering Wellington City in the suburb of Linden, the Transmission Gully Motorway ends, and SH 1 merges on to the Johnsonville-Porirua Motorway. The motorway gradually ascends through Tawa before reaching Johnsonville. Here, the motorway ends, and SH 1 as a six-lane arterial road steeply descends through the Ngauranga Gorge to the Ngauranga Interchange, on the shore of Wellington Harbour. At Ngauranga, SH 1 becomes the Wellington Urban Motorway, skirting the shore of the harbour then passing the city centre to the west. The motorway ends at Te Aro, where a one-way system takes traffic to the Basin Reserve. Northbound traffic uses the Wellington Inner City Bypass (opened 2007), while southbound traffic uses Vivian Street. From the Basin Reserve, SH 1 travels through the Mount Victoria Tunnel to Wellington's eastern suburbs and Wellington International Airport. SH 1 ends at a roundabout at the entrance to the airport. South Island (SH 1S) The South Island section of SH 1 starts in Picton, adjacent to the railway station. Leaving Picton, SH 1 rises steeply to cross the Elevation saddle into the valley of the Tuamarina River. It descends alongside this river and across the Wairau Plain before reaching Blenheim. SH 1 passes through Weld Pass and Dashwood Pass to enter the Awatere Valley, then countiuses southward before passing Lake Grassmere. From the small town of Ward the highway heads to the coast and follows it to Kaikōura. After passing Kaikōura, it veers inland, twisting tortuously through the Hundalee Ranges before emerging at the northern end of the Canterbury Plains. The section of highway between the Clarence River and Hapuku Rivers north of Kaikōura was closed from 14 November 2016 to 15 December 2017, due to damage from the 2016 Kaikoura earthquake. SH 1 passes through Amberley and Woodend before becoming the Christchurch Northern Motorway and bypassing Kaiapoi to the west. At The Groynes west of Belfast, the motorway narrows to a four-lane divided arterial. SH 1 continues around the north-western urban fringe of Christchurch, passing just east of Christchurch International Airport. At Hornby, the highway turns south-west, narrows to a two-lane undivided road and