 It reduced road travel times and considerably improved access between Wellington and Porirua by eliminating the need to use the narrow winding road through the bottom of the Tawa valley in the Glenside area.The second section, from Takapu Road to Porirua, opened about 1956 and allowed through traffic to bypass the lower speed road through Tawa.The Johnsonville bypass connecting the south end of the motorway to the top of Ngauranga Gorge opened about 1958 completing the four-lane road link between Wellington and Porirua.