By Cliff Slater

A recent column ("Transit alternatives abound," Dec. 29) discussed briefly a proposal for a transitway as being preferable to a rail-transit line. This column attempts to answer the many questions that readers asked about it.

A transitway or busway is an evolving concept, the latest version of which is HOT lanes, or high occupancy/toll. These are highway lanes with priority for buses and other very-high-occupancy vehicles such as vanpools, which go free, with any excess capacity opened to automobiles paying an electronic toll.

The two-lane, reversible HOT transitway would be elevated on pedestals between the first on-ramp at the H-1/H-2 merge near Waikele and the last off-ramp at Pier 16 near Hilo Hattie. Traffic on it would flow one-way into town in the morning and reverse at noontime to run in the 'ewa direction in the afternoon.

Either an elevated rail-transit line or an elevated transitway would provide a high-capacity transit spine along the Leeward Corridor. However, to understand why the transitway would be far preferable, one must understand some commuting facts, and some of the seemingly immutable laws of public transportation use, which are:

• A single lane of transitway dedicated to buses carries, in practice, twice as many passengers as most rail lines in the United States, and some come close to New York City's busiest line, the 8th Avenue, which carries 43,000 passengers per hour in the peak direction. New Jersey's Route 495 single-lane transitway carries 30,000 passengers per hour, whereas the largest rail volume outside New York City is Boston's Red Line, with only 13,000 per hour. Washington, D.C.'s I-395 transitway carries 21,800 per hour versus the Chicago N-S rail line's 11,400. All of these compare favorably to street railways, such as Portland's, which carries just 1,980 per hour.
• The greatest inducement to use public transportation is when riders can go door-to-door; commuters do not like to transfer, and so it deters their use of public transportation.
• Since rail-transit lines do not integrate well with roads and highways, it virtually assures that the great majority of rail commuters have to transfer. On the other hand, buses on transitways continue on to regular roads and highways, and that allows more flexible routing.
• The average speed of the rail line currently being proposed for Honolulu would likely be around 23 mph, which is the upper speed limit for elevated and subway rail systems with stops every half-mile — distance between stops being the major determinant of average speed.

The advantages of a transitway over rail transit are speed and continuity of travel. For example, imagine that a new reversible transitway is open and we are going to take a bus to work in town from beyond the H-1/H-2 merge. From the closest stop, the bus picks us up, takes us by local roads to the transitway, and then, at 50 mph, moves us steadily into town until we exit at the Pier 16 off-ramp onto Nimitz Highway. From there it will be a short, if slow, drive to Bishop Street to our workplace.

On the other hand, imagine that the rail line opens along the same alignment as that planned in 1992. You walk to your local bus stop, take the bus to the nearest rail station, board the train, then travel at 23 mph into town to the nearest stop, with the likelihood that it will be farther away from one's destination than would be possible by bus.

Higher speeds, together with the ability of the bus to reach closer to commuters' workplaces and homes (and thus make transfers less likely) offer commuters the overall time reduction that can allow buses to successfully compete with the automobile, which must stay on the freeways, albeit now somewhat less congested.

Cliff Slater is a regular columnist whose footnoted columns are at www.lava.net/cslater.