Some suggested that the existing coastal route should be upgraded, rather than building a completely new route.
This was the original recommendation of the Regional Council, and was put forward as the primary alternative to building Transmission Gully.
From SH1 at Mac Kays Crossing, north of Paekakariki, the route rises steeply to the Wainui Saddle and follows Transmission Gully down to Porirua Harbour's Pauatahanui Inlet.
It continues south around the outer edge of the Porirua urban area, at one point crossing a 300-metre-long and 90-metre-high bridge, and rejoins SH 1 at the boundary of Porirua and Tawa.
Emergency relief from the north could be quickly supplied by Transmission Gully and the Wellington and Lower Hutt localities would be re-connected to the north.
Some opponents of the Transmission Gully project believed that its overall cost is too high, and that the region has insufficient funds to spend on it, with a benefit/cost ratio of 0.6.
Peter Dunne, MP for Ohariu, says that "[i]mproving Wellington City's northern access and egress is a vital key to the future economic performance and prosperity of the whole region, and the Transmission Gully highway is a vital link in that chain".
Opponents of Transmission Gully stated that there were better ways to improve access to Wellington.
On , national grid owner Transpower applied for consent to the Kapiti Coast District Council to rebuild its Valley Road, Paraparaumu substation to 220 k V and build two short transmission lines to connect it to the two Bunnythorpe to Haywards 220 k V lines to the east.
This would allow Transpower to demolish the existing 110 k V line between Pauatahanui and Paraparaumu through Transmission Gully, rather than having to relocate it around the motorway.
Public submissions to the Council were in favour of Transmission Gully, and the Council has changed its stance in response.