Top 5 Civil Engineering Projects of the Year
February 17, 2010
The American Society of Civil Engineers recently announced five finalists for the group's annual Outstanding Civil Engineering Achievement award. The results are difficult to dispute.
Selected from a group of 28 entries, the 2010 finalists are as follows.
Arrowhead Tunnels of the Inland Feeder Program - San Bernardino, Calif. The Metropolitan Water District (MWD) of Southern California's Inland Feeder consists of three separate tunnels, together totaling 18 miles. The Arrowhead Tunnels project, which consists of two 19-foot excavated-diameter tunnels, is a key segment of the MWD of Southern California's 44-mile-long Inland Feeder, created to deliver about 646 million gallons of emergency water a day to millions of residents, MWD employee magazine People.Interactive explains.
"Tunnel excavation was challenging, with highly variable ground conditions. The tunnel alignments cross active splays of the San Andreas fault in three locations, encountering sheared rock and raveling and squeezing ground," tunnel engineering firm Jacobs Associates says of the Arrowhead Tunnels project. The project required the use of probe holes to assess ground conditions ahead of huge tunnel-boring machines (TBM), which, combined with the use of strain gauges to monitor tunnel pressure, were able to dig faster and with fewer stops and starts.
Following excavation, precast concrete liners, mortar and steel pipes were installed. According to Jacobs Associates, which played numerous roles in the project's planning and execution, "the design incorporates several unique features." Ultimately, the tunnel's lining design is expected to allow it to withstand a magnitude 8.0 earthquake.
Central Link's Section 710 - Seattle, Wash. For Sound Transit Central Link's Light Rail, the challenge of Section 710 lay in building a deep-mined transit station and one mile of twin rapid transit tunnels under Beacon Hill as part of the region's new light rail system extending from downtown Seattle to SeaTac Airport.
"The tunnel needed to be deep to avoid disrupting businesses and traffic on the surface, plus it would involve construction in extremely unstable soils, including stratified silt, sand and clay," according to the American Council of Engineering Companies of Washington (ACEC Washington).
The engineering design team used the Sequential Excavation Method (SEM) the practice of digging a tunnel in sections, supporting each segment as you go to carefully manage the multiple soil challenges. "This approach to deep, complex tunneling in very poor soils, at a depth and a diameter close to twice that previously done, resulted in the largest soft ground SEM tunnel in North America," the ACEC Washington says.
This project also required new drilling techniques, including the use of an earth pressure balance tunnel-boring machine (EPB-TBM). Running tunnels were lined with a single pass, pre-cast concrete liner fitted with gaskets to ensure water tightness. Despite the poor soils, the tunnels were completed with virtually no ground settlement or aboveground disruption.
Lakeshore Environmental Enhancement and Education Project - Mequon, Wis. Bordering a steep, precarious bluff above the water, Concordia University Wisconsin's (CUW) campus was essentially cut off from direct lakefront access. Extensive erosion of the bluff itself compounded this problem.
Planning for the Lakeshore Environmental Enhancement and Education Project (LEEEP) began in 1999, with actual work on the bluff stabilization project beginning in 2005, according to the school. "The stabilization effort involved removing material from the University's steep 2,700-foot long Lake Michigan bluff, stabilizing and seeding the entire site with native species, and constructing major shoreline revetment and breakwater structures, as well as managing a 34-acre fill site," the Wisconsin chapter of the American Society of Landscape Architects (WIASLA) explains.
"Bioengineering and aquatic biology were fused with landscape architectural practices to "meet the project's challenging technical requirements and provide effective interdisciplinary solutions providing stabilization, restoration and public access," the WIASLA says.
State Capitol Seismic Base Isolation - Salt Lake City, Utah When the Utah State Capitol building, located several hundred feet from an active fault capable of a magnitude 7.3 earthquake, failed seismic evaluations, state authorities embarked on a base-isolation retrofit to protect the massive and ornate building. Popular Mechanics explains that the foundations had to be "pulled out without raising or lowering the 132-million-pound building by more than 1/16th of an inch."
According to VSL, a designer and manufacturer involved with the project, "the designers developed a method of permanently re-supporting the rotunda of the capitol with a unique circumferential post-tensioned concrete load transfer scheme that necessitated the need for temporary support of the existing footings, eliminated the risk of settlement, minimized the need for demolition and avoided cutting or damaging the existing footing reinforcement."
Ultimately, contractors strengthened the capitol using 256 state-of-the-art seismic isolators beneath the building, while reinforcing the dome and other structural elements.
Sutong Bridge in Nantong City - Jiangsu Province, China The Sutong Bridge, the only non-U.S. finalist contending for ASCE's latest annual OCEA award, lies between Nantong and Changshu in the east of China's Jiangsu province. Spanning the Yangtze River, the all-China project is designed to cut travel times from Shanghai to Nantong from four hours (by ferry) to one hour via six-lane expressway.
The Sutong Bridge has a span of 1,088 meters (3,570 ft.), setting a world record for the longest span cable-stayed bridge. It is also the world's first with a main span that exceeds 1,000 meters. The previous record holder, Japan's Tatara Bridge, has a main span of 890 meters.
The bridge is supported by soaring steel and concrete towers that stand over 300 meters tall, making it the world's highest bridge tower, according to World Records Academy. Upon completion, the bridge set other world records: the deepest foundation of any cable-stayed bridge (120 meters) and the longest stayed cable (577 meters).
The OCEA winner in 2009 was Orange County, California's Groundwater Replenishment System, the largest water purification reuse project of its kind in the world. This year's award winner will be announced on March 25, 2010.
...2010 Outstanding Civil Engineering Achievement Award Finalists American Society of Civil Engineers, Dec. 11, 2009
The Light at the End of the Tunnels by Rob Hallwachs People.Interactive, August 2009
Arrowhead Tunnels of the Inland Feeder System Jacobs Associates
Light Rail Tunneling Earns Hatch Mott MacDonalds/Jacobs Engineering Top 2010 Engineering Excellence Award American Council of Engineering Companies of Washington, Jan. 25, 2010
CUW's Bluff Stabilization Project Reaches Finals in Worldwide Competition Concordia University Wisconsin, Dec. 16, 2009
Lakeshore Environmental Enhancement and Education Project - Concordia University Wisconsin American Society of Landscape Architects (Wisconsin chapter)
The Top 5 Engineering Projects of 2009 by Erik Sofge Popular Mechanics, Dec. 10, 2009
Longest Cable-Stayed Bridge - The Sutong Bridge Sets World Record World Records Academy
Groundwater Replenishment System of Orange County, Calif. Named 2009 OCEA Winner
ASCE News (American Society of Civil Engineers), May 2009