The Queen’s Medical Center is seeking city approval for an estimated $100 million expansion of its bustling 17-acre campus on Punchbowl Street.

The state’s largest private hospital — designated as the highest-level trauma center in the Pacific — is planning a major redevelopment that includes two new towers for outpatient and inpatient services, additional parking garages and a possible Miller Street pedestrian bridge. The construction will take place over the next 15 years and is designed to accommodate a substantial growth in patients as Hawaii’s population ages.

"Unfortunately we’ve kind of grown into our campus. … We wanted to be sure our nextmove is very much in line with what we anticipate the demand to be when we get the project built," said Todd Kanja, Queen’s director of engineering services. "The need for care is going up, so we want to bethere to help."

Queen’s has shared its proposal with area residents and said it has full support of the neighborhood board. It expects city approvals by October and construction to begin in two years once planning and design work is completed.

The first phase of the project, to be completed by 2015, involves redeveloping Lauhala Street and erecting a new 200,000-square-foot tower for outpatient services as well as a separate 600- to 700-stall parking garage. The Hawaii Medical Library will converted into an office building, while Pauahi Tower will get an exterior face lift.

A second phase, projected to conclude in 2020, will include an expansion to the General Services Building, used for education and research, and a possible Miller Street pedestrian bridge connected to the parking structure.

The final phase, winding down in 2025, includes a new 200-bed inpatient tower with an estimated 230-stall underground parking garage. The Punchbowl campus will expand to 18.7 acres.

The plan is subject to public hearings.

"Queen’s is a well-run operation, and they put a lot of thought into it — a lot of plans have been made public," said Burton White, vice chairman of the Downtown Neighborhood Board. "Their expansion to date has operated well. I can’t imagine that stifling a health care organization can help it navigate for the future."

The nonprofit health care center, a subsidiary of The Queen’s Health Systems, had originally proposed in 2004 a five-year campus overhaul that included expanding the Queen Emma Tower and adding a sister tower. That plan was revised due to the economic downturn and continued pressure to reduce costs.

The scaled-down 15-year plan focuses primarily on expanding outpatient services to cut more expensive hospitalization costs.

"We’re anticipating a lot of thingsmoving from an inpatient basis to an outpatient basis. If there’s a way wecan deliver care to people so that they can go home as opposed tostaying in the hospital, costs will be a lot lower," Kanja said. "There’s much more of a focus to try tocontain costs as best as everybody can moving forward. There’s going to continue to betremendous cost pressure in the need for services."

Expanding outpatient services and reducing time in the hospital are things that aging area residents have embraced.

"It reduces cost and it’s healthier — the less time somebody’s spends in a hospital, the less chance they can pick up diseases," said Lynne Matusow, a member of the Downtown Neighborhood Board. "It’s important for somebody’s mental health if they’re home, they’re comfortable and in familiar surroundings with family, with friends. It’s much nicer than being in a hospital."

The Queen’s Medical Center was founded as Queen’s Hospital in 1859 by Queen Emma and King Kamehameha IV. The king and queen went door to door to collect money for the hospital. At the time, disease brought to the islands by recent arrivals threatened the existence of Native Hawaiians.

Today the medical center is the largest private hospital in Hawaii with 533 beds. It has more than 3,000 employees and more than 1,200 physicians on staff. The campus consists of 23 buildings.