The Honolulu rail ridership projection is an outlier when compared with actual ridership in other cities with populations of less than 4 million.  The Honolulu rail and Tren Urbano in San Juan, Puerto Rico, were both planned by PB Consulting and overseen by the Federal Transit Authority.  When the Tren Urbano began operating, ridership was one-fourth of what was projected.  In order to increase ridership, fares were made free(!) for a period of time.  After years of operation, the Tren Urbano has never attained ridership projections.
http://www.civilbeat.org/2017/02/the-impending-honolulu-rail-ridership-debacle/