The City Council has many difficult decisions before it, but the selection of rail technology should not be as tough as this.

On Wednesday, the council voted to give itself more time to select what kind of mass transit system Honolulu will build. Indeed, this will be the city's most expensive public-works project ever.

Many of the cost factors — land acquisition and construction materials, for example — are difficult, if not impossible, to control. This makes it more crucial than ever to select a technology with an eye to economy: reliability, ease of maintenance and a range of vendors that can compete and keep costs competitive.

Without a doubt, steel wheel on steel rail is that technology. But in recent weeks, the discussion has snagged on the issue of rail noise, with residents complaining that steel-on-steel will be too screechy for Paradise.

That's an understandable reaction from people whose only experience with rail has been visits to big Mainland cities, whose metro systems are much older and, admittedly, sometimes rattly.

But council members should know better. They've had the benefit of information from a panel of experts. And the state of the art of noise reduction in steel-on-steel systems today holds far more promise than it once did.

Even the BART system, a fairly quiet and smooth system familiar to many Honolulu residents, is noisier than what this city could expect, owing to its age and what experts in the field describe as an atypical design. And the creaky transit systems of New York or Chicago? Not even the same animal.

Acoustical analysis suggests that the high-speed train of Vancouver, B.C., comes closer to what Honolulu would get in a steel-wheel system. There is noise, but much of it can be shielded around the rail, and the fact that the Honolulu guideway would be almost entirely elevated would mitigate that further.

The rails themselves are welded continuously, which eliminates the clacking sound in old systems as wheels roll over the bolted rail joints. Wheel squeal is significantly reduced through system design, since it generally occurs where there are sharp turns — not anything anticipated in the Honolulu alignment.

A comparison with the competing technologies must include these observations: