The rail makes a huge turn towards Waipahu.
A bicycle is a good prop when finding cahes. You can use it to block muggle eyes while retrieving caches. You can use it to get around in tight areas. You can use it where cars are not allowed. So get on a bike and start pedaling.
If you are doing the loop it is about 6 miles. Going from South to North is slightly uphill. North to South-downhill.
No bike? Caches can be grabbed with a little walking.
BYOP
Congratulations to the FTF trio of ormustr,CacheAngel+ & Skotlee for the quick find.