More than 40 million passengers fly in and out of Sky Harbor International Airport in Phoenix every year. City officials couldn't risk stifling this sizable economic engine during construction of a much-needed passenger train project.

To stay out of the way of planes, PHX Sky Train's guideway design takes it 90 ft over an active taxiway—billed by airport officials as a worldwide first—and then dips underneath two more taxiways before rising up to pass over a passenger concourse.

To build it, construction crews have to keep a low profile, too. "The priority is operating the airport," says James Kyle Kotchou, special projects administrator at the City of Phoenix Aviation Dept. for the $1.5-billion project. "Sometimes that's hard, but we've laid that out early on before construction started, and it's disseminated down to the subs so the bids include it."

Multiple Phases

The project, designed by Gannett Fleming, Phoenix, is being completed in three phases. The many contractors, engineers and subcontractors involved hold frequent coordination meetings and keep lines of communication open to aid with the many hand-offs between project components.

Phase 1, totaling $644 million, connects Terminal 4 to Phoenix's light rail with 1.7 miles of elevated guideway. Construction included a maintenance facility built by Phoenix-based Weitz Co.; three train stations and concrete superstructure for the guideway built by Hensel Phelps Construction Co., Phoenix; and guideway fit-out by Weitz under a contract with Montreal-based automated train supplier Bombardier.

Phase 1 construction was completed earlier this year, and systems testing began last month to prep for passengers in early 2013.

The $244-million Phase 1a began construction last year and will add 0.6 mile of guideway and a single station serving both Terminals 2 and 3. Although not initially planned to be constructed until 2020 along with a longer extension to the Rental Car Center, the airport was able to accelerate this portion through "higher-than-expected passenger levels in recent years combined with operating budget reductions," says Jay DeWitt, deputy aviation director for financial management.

The third phase to the rental car facility is still in the early planning stages, so exact costs aren't set.

The overall project is funded using airport bonds, which rely on various airport revenue sources. Along with maintaining a good credit rating to access favorable financing terms, DeWitt says a key financial strategy was the timing of the bond sale. "The airport established a commercial paper program with its banking partners to provide the short-term financing until the time was right to sell the long-term 30-year bonds," he says.