The HRS operates over the 8 mile plus portion between their property (yes, they now *own* 4.266 acres) at Ewa to just beyond bridge 35 at Kahe Point (directly across from the HECO power plant).
But I believe that the rails east of (or heading toward Honolulu) Fort Weaver Rd were removed. The right-of-way, however is intact. While one might consider it rail-banked, it was never so designated or included in any rails-to-trails project that I am aware of. The final years of Naval operation of the line did not use that portion.
As to what rail exists on federal properties, I don't know. But reclaimation of any rail would be a good idea in any case.