Mayor Mufi Hannemann is true to his motto when it comes to Honolulu's mass-transit plan.

Do we need it? Can we afford it? Can we maintain it? For the City's fixed guideway project, the answer to all of these questions is yes.

There is no question about the need. Ask the thousands of Honolulu residents and visitors who are stuck in traffic daily.

On the issue of affordability, the city cannot just make up numbers so that projects appear affordable. We are accountable to the public and to the federal agencies who are overseeing the mass-transit project because the city is requesting federal funding.

Our cost projections must be based on federally approved models and formulas and are the result of thorough study and evaluation. The Federal Transit Administration must review and approve such cost estimates before federally funded transit projects are allowed to move forward. Indeed, the FTA also enlisted independent, licensed estimators to review such projections, and they have concurred with the methods and estimates to date.

We've taken great pains to guard against cost overruns, which is why construction costs are only about half of the total estimated project cost. The city is required to take measures to minimize the chance of cost overruns by including a high percentage for contingency and for engineering. We also have a solid financing plan that demonstrates the affordability.

Cliff Slater claims we can't afford the mass-transit project, but that's because he's speculating about what the actual cost is.

Responsible citizens should question Slater's numbers. We certainly don't believe his estimate of $900 million for the HOT lane project, which he is an advocate for, is anywhere near the true cost, and here's why: His construction costs are grossly understated, there are no contingency or other costs associated with risk management and there's been no outside review of any of his figures.

Can we afford to maintain a mass-transit system? The key to answering this question is system efficiency. We don't have enough land to keep adding more freeways and roads to accommodate cars in the future, and we can't afford to keep adding buses. A single mass-transit vehicle is designed to carry about four and a half times more passengers than a single bus. That's the savings we'll realize in the long run. Maintaining a large fleet of buses would be much more costly than maintaining an efficient fixed guideway.

The better approach is to have our buses part of an integrated multimodal system with fixed rail as the centerpiece. And making this investment today will ensure that our children will be able to afford maintaining the transit service.

Lastly, there are other cities that have managed to build their mass-transit projects within or even under budget. St. Louis completed its mass-transit project under budget in 2001, Denver, Dallas and Sacramento in 2000, Salt Lake City in 1999 and Portland in 1998.

Those of us working in Honolulu's Department of Transportation Services come under the strict oversight of the Federal Transit Administration and more importantly, as the mayor continues to insist, we're bound by our duty to the taxpayers of Honolulu.

The bottom line is the need for mass transit on O'ahu has been with us for decades and is long overdue. We're working hard to make sure we do it right and by the book. We have engineers, planners and consultants working on our project in a professional manner on a daily basis.

No one feels the weight of public expectation and accountability more acutely and we are working diligently so that Honolulu citizens can finally have the mass-transit system they need and deserve.

Toru Hamayasu is chief planner for the city's Department of Transportation Services. He wrote this commentay for The Advertiser.