I do not live in Hawaii, but from what I can tell (from visiting one time and looking at what maps/analyses I can find in 10 minutes of web search) most of the traffic sources and destinations in Oahu are within a couple miles of a single 20-mile-long stretch of freeway (H1 / H201). We’re talking about hundreds of thousands of people trying to drive every morning/evening along the same stretch of freeway in individual private vehicles (3–4 lanes wide in each direction), instead of riding some more space-efficient mode of transportation along the same route.