Traffic relief can come in various ways.   First, you need to widen the freeway going west just after the Mililani off ramp and before Waikele where 6 lanes turns into 3 lanes.    From West going into town, the freeway narrows to 3-4 lanes right around Fort Shafter.     

Secondly, our traffic lights are poorly synchronized so feeder streets constantly stop the main flow of traffic.

UH West Oahu must be expanded or the community colleges to prevent the need to attend the UH Manoa campus.   More classes can be conducted by Skype or online to also reduce the need for in person   Maybe make classes start later so people don't need to be on the road at 6:30 am.

These few items could have been built already for a small fraction of the cost of rail.

I have other ideas but I'm running out of space on this post.