March 2009 | Volume 79, Number 3

ON THE COVER:
The new California Academy of Sciences building, in San Francisco’s Golden Gate Park, has been referred to as the greenest museum in the world because of its undulating, 2.5 acre (1 ha) vegetated roof and its other environmentally benign features. Porthole skylights that can be opened and closed to facilitate natural ventilation of the interior spaces cover one of the largest of the seven hill-like shapes on the roof. These portholes are among the numerous systems throughout the building that are controlled automatically by temperature sensors and other monitoring devices, including a pair of small rooftop weather stations.

(Photograph © Tim Griffith.)

Features

Under One Green Roof

By Robert L. Reid

Called the greenest museum in the world, the new California Academy of Sciences building is the largest public structure in the world ever to achieve platinum certification in the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) Green Building Rating System. It is also the only facility to house an aquarium, a planetarium, a natural history museum, and a scientific research institution within a single building.

Tight-Fit Tunneling

By Keith A. Wargo, P.E., Paul A. Roy, P.E., M.ASCE, Marco D. Boscardin, Ph.D., P.E., M.ASCE, Andy J. Miller, and Kevin DiRocco, P.E., M.ASCE

Design and construction of a light-rail tunnel under the Allegheny River in downtown Pittsburgh had to contend with challenging ground conditions, obstructions, steep grades, tight curves, and shallow cover. After careful preparation and innovative operation, crews operating the tunnel-boring machine recently completed work on the twin 22 ft (6.7 m) diameter tubes that form the tunnel.

A Bridge in Flight

By Fredric S. Berger, P.E., M.ASCE, Tanja Wilcox, L.A., and Lee Ahlstrom, P.E., M.ASCE

Before beginning the design of a bridge to carry a high-speed expressway across a steep canyon in Japan, engineers consulted with members of the nearby community and considered local artistic traditions. The result is an extradosed bridge that blends with its surroundings while incorporating important local and national symbolism.

Rebuilt to Last

By Paul A. Harren, A.M.ASCE,and John L. Watts, P.E., M.ASCE

After a dry dock for U.S. Navy submarines experienced a wall failure, engineers were hired to examine two similar docks and to devise a strengthening process that would ultimately involve encasing the corroded sheet-pile walls with concrete, adding 50 years to the lives of these 40-year-old docks. The collapse of a steel sheet-pile wall in a dry dock in Connecticut that is used to maintain and repair U.S. Navy submarines raised concerns about two other similarly constructed docks. To ensure that the docks could maintain their navy certification and to extend the lives of the docks by 50 years, a team of engineers devised a strengthening scheme that relied on encasing the steel walls in concrete.

COURTESY OF WEST NIPPON EXPRESSWAY, LTD., AND THE LOUIS BERGER GROUP, INC., left

COURTESY OF ZAHA HADID ARCHITECTS, top right;
TEXAS A&M, middle left ;
JEFFREY G. KATZ /CENTERSPAN PRODUCTIONS , middle right;
©NIKKENSEKKEI, LTD., bottom right

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