lanes of traffic." On commencement of the project the new Minister "symbolised the new administration's optimism and the power of machinery over the picks and shovels by getting into a bulldozer and wrecking a pile of wheelbarrows". The Ngauranga Gorge four-lane highway was officially opened on 4 November 1939. Motorway The first section of the Johnsonville–Porirua Motorway opened in December 1950 but traffic was funnelled through Johnsonville until a bypass was completed towards the end of the 1950s joining the Gorge's four lanes to the Motorway. A junction controlled by lights remained between the two highways until the end of the 20th century. During the 1960s the road through the gorge was widened from four to six-lanes. This required considerable excavation and the rock removed went into harbour reclamation for the construction of the Wellington Urban Motorway completed in 1969. The Ngauranga Interchange flyover joining State Highways 1 and 2 was finished in 1984. The Newlands Interchange, at the top of the gorge, was constructed in 1997–98 to replace the simple junction controlled by traffic lights, which caused a large amount of congestion. Further excavation and widening of the gorge was required to construct the interchange and a short uphill section between Abattoirs Road the Newlands exit was widened to four uphill lanes. The North Island Main Trunk railway crosses the bottom of the gorge via an overbridge between the Tawa No 1 and Tawa No 2 Tunnels of the Tawa Flat deviation. There is an industrial area and some retail outlets at the bottom of the gorge, where there was previously an abattoir. Another abattoir and a quarry are part way up the gorge. Maintenance On 11 July 2017 the southbound (down) lanes were closed by a rock slip about mid-day (until 6 am the next day) due to a "debris avalanche" on a modified slope above the lanes. Notes References External links Ngauranga Gorge 2015 Photo of Fall in Lower Gorge (Fig 2) from 1911 paper Photos of road construction in 1938/9 Wellington City Canyons and gorges of New Zealand Rock formations of the Wellington Region State Highway 1 (New Zealand)