At the northern end of Transmission Gully, the new motorway connects with the existing SH1 (Kāpiti Expressway) just north of the Mackays Crossing interchange.
Motorists travelling southbound to Pukerua Bay or Plimmerton can use either the Mackays Crossing or Paekākāriki off-ramps to access the ‘old SH1’ coastal route – renamed and signed as SH59.
Motorists travelling northbound on Transmission Gully to get to Paekākāriki or further around the coastal route, should take the off-ramp at Mackays Crossing and then travel south via SH59. Walking and cycling are prohibited on motorways, so all southbound on-road cyclists must take the off-ramp at Mackays Crossing to continue along the coastal route.
This animated video shows the Transmission Gully motorway route from Mackays Crossing through the Wainui Saddle.