The magazine TRP (The Railfan Press?) had a recent issue with an article about the later years of the Oahu switching the harbor area. It is the only copy of that magazine that I've bought and it was because of the Oahu GE 47-tonner on the cover, etc. This is the same publisher that has put out the pictorials for the Hawaiian Ry society -- most of the other booklets are eastern standard gauge.
When I visited the railroad when I was 17 years old back in 1966 during a family vacation to Hawaii, the railroad was operated out of the offices of Dillingham Dridge and Construction (or something like that).
Brian Norden