(Blue Diamond Road) Corridor Study - Regional Transportation ...

4. Evaluation Methodology RTC SR-160 Corridor Study
Exhibit 4-1 provides a conceptual overview of the carrying capacity of major mass transit
alternatives. Because of its high per mile capital costs, heavy rail (subway) and elevated
rail systems are considered feasible only in central business districts (CBDs) in dense
populated metropolitan regions where a substantial share of commute trips are bound for
the central city. Generally, subways are considered only for regions where transit demand
exceeds 15,000 passengers per hour. In regions where heavy rail is not considered a
feasible alternative, transit agencies have invested in Light Rail Transit (LRT) systems which
operate largely at-grade on city streets.
Like heavy rail, LRT systems are typically retrofitted into high-density urban corridors where
high transit demand cannot be sufficiently met by existing fixed route bus services and the
expected benefit in new ridership justifies the economic costs of the fixed investment. Light
rail system typically carry anywhere between 5,000 and 12,000 passengers per hour. Rarely
are LRT systems considered suitable for corridors that currently possess daily ridership
below 3,000 passengers per day, unless enough commercial development is anticipated.
Where anticipated ridership levels are not high enough to justify a fixed guideway rail
investment, transit planners have turned to an array of rubber-tire bus rapid transit (BRT)
technologies. BRT systems have increased in popularity because they offer flexible options
that can be scaled upward at comparatively lower marginal fixed costs to meet growing
demand.
4-5