On most days there is a big backlog of traffic at Kunia road on H-1 townbound, sometimes all the way back to North-South road and even Makakilo. There is a lot of room on the median and on the west bound side if they would just start the zip lane at North South road instead of in Waikele it would make a big difference.
Response from state Department of Transportation:
In 2014, HDOT produced a Zipper Lane Extension Study that looked at extending the Zipper Lane westward to either Makakilo or Kualakai. It was found that the anticipated cost of the extension, which would require widening of structures, and the impacts to those coming in from Central Oahu made the initiative infeasible.