If anyone drives on the freeways, it's easy to see how you can improve traffic flow.   Going west, the freeway turns from 6 lanes to 3 just before you reach Waikele.   And going from west to Honolulu, the freeway turns from 4-5 lanes down to 3 when you reach the Fort Shafter are.   Both areas need to be widened and then Nimitz and downtown needs better traffic light synchronization.  

These 2 things (much cheaper than rail) would create much greater traffic freedom than building a rail to nowhere that will have significant monthly subsidy and maintenance costs.