It would be easy to just look over the Bay’s shoulder and copy what it had. Caltrans, however, wants every bridge to be a signature bridge. So when it came time to create designs for the Benicia-Martinez Bridge, which would carry I-680 between the city of Benicia and the city of Martinez in the San Francisco Bay Area, they wanted to sketch from scratch.
“We have a number of different types of structures in the Bay Area,” David Ambuehl, construction manager for Caltrans on the Benicia-Martinez job, told ROADS & BRIDGES. “With all of these signature structures going up, [Caltrans] decided to try to mix it up a bit.”
Being different also meant dealing with the difficult. The challenge of long spans constructed under the cast-in-place balanced cantilever method, seismic considerations and environmental and Coast Guard issues all had to be met head-on by prime contractor Kiewit Pacific Co. Those obstacles, plus the enormous size of the project (8,790-ft bridge at a price of $800 million) made the Benicia-Martinez Bridge a clear No. 1 choice on this year’s ROADS & BRIDGES Top 10 Bridges list.
“We have had a lot of hurdles to get over, but we work really well together, and with each hurdle cleared we certainly feel better about the progress,” said Ambuehl.
The hurdles stood tall early in this race. First there was the attempt to perfect the concrete mix design, which demanded a 10,000-psi compressed strength. Ambuehl said it took well over 100 formulas before the ideal one was found. Then came the location of the bridge. Caltrans wanted to build to the west of the existing steel structure. However, ship traffic due to oil refineries in the area and difficulties purchasing right-of-way flipped the new concrete bridge over to the east side.
Long span lengths forced another issue. The maximum span length of the Benicia-Martinez is 660 ft long, and if it was any longer Caltrans would have been forced to go with a different bridge type. A heavy dose of post-tensioning and segment depth at the pier tables helped resolve the challenge. The segments are 40 ft deep at the tables, and thin to 12 ft deep at mid-span.
The Benecia-Martinez Bridge is designated a lifeline structure in the Bay Area, which means it needs to be open to emergency traffic 24 hours after a major earthquake. To keep the span structurally sound, 17 footings are drilled 250 ft deep, the final 100 ft in bedrock. The bedrock, however, was prone to fracture during the drilling process, which created another one of those hurdles.
“When you started to drill, you could experience cave-ins because the highly fractured rock would fall apart,” said Ambuehl.
After drilling a series of eight or nine piles, crews built a concrete platform that mounted on the piles and brought in a rotator rig. The rig grabbed a steel shell pile, which was about a foot smaller than the 8-ft-diam. piles and had teeth on the end of it, and drove it to the bottom of the foundation.
“They would spin it all the way to the bottom and were then able to put their cage inside that shell, and as they poured the concrete the steel shell was pulled out,” explained Ambuehl.
Lightweight concrete used to form the superstructure, the extra post-tensioning and midspan hinges also make the bridge seismic-tough.
As of mid-October, 344 of the 345 segments were cast. The contractor still had six closures left. Once the closures are executed, the bridge deck will be finished. To avoid any imperfections, the deck was poured extra thick so the contractor could come in and grind it down to a smooth finish. The bridge should be open to traffic in the summer of 2007.
Number 1: Benicia-Martinez Bridge
Cost: $800 million
Length: 1.4 miles
Type: Cast-in-place balanced cantilever
Designers: T.Y. Lin International/CH2M Hill
Contractor: Kiewit Pacific Co.
Number 2: Lime Kiln Bridge, Colchester/South Burlington, Vt.
Cost: $12.6 million
Length: 1,870 ft
Type: Open-spandrel concrete arch
Designer: VHB/Vanasse Hangen Brustlin Inc.
Owner: Vermont Agency of Transportation
Contractor: Kubricky Construction Corp.
This open-spandrel concrete arch is the only highway bridge of its kind in Vermont. The bridge has precast/prestressed concrete box beam approach spans made of high-performance concrete. The concrete deck is protected from deicing salts by a membrane system.
Number 3: Rte. 9 over the Bass River, Bass River Twp., N.J.
Cost: $13.6 million
Length: 470 ft
Type: Prestressed concrete
Designer: Hardesty & Hanover
Owner: New Jersey DOT
Contractor: J. Fletcher Creamer & Son Inc.
To combat the salt-water environment, the bridge has several durability-increasing features. All beams are made of precast concrete, and high-performance concrete was used throughout the entire structure, from the drilled shafts up to the bridge deck. All concrete has a corrosion inhibitor admixture.
Number 4:Hickory Street Bridge, Warren, Pa.
Cost: $12.9 million
Length: 516 ft
Type: Prestressed concrete box beam
Designer: Michael Baker Jr. Inc.
Owner: PennDOT, Engineering District 1-0 (City of Warren)
Contractor: Mascaro Construction
The designer included special architectural treatments in the bridge’s design, including arch-façade panels. Mussel surveys that protected habitat in the project site also were conducted. The historic site was temporarily covered during construction so equipment could pass through without damaging the area.
Number 5: Sanibel Island Causeway Reconstruction, Sanibel/Ft. Myers, Fla.
Cost: $81 million
Length: 17,424 ft
Type: Prestressed concrete Florida bulb-T superstructure
Designer: Hardesty & Hanover, URS Inc.
Owner: Lee County, Fla.
Contractors: Jacobs Civil Inc., Boh Bros. Construction Co. LLC
This job requires the construction of three separate bridges to connect Sanibel with Fort Myers. Bridge A will be a 70-ft vertical clearance fixed-span bridge. Bridge B will be raised a minimum of 4 ft above the splash zone, and Bridge C will be a 26-ft vertical clearance fixed-span bridge.
Number 6: I-355 Extension Bridge, Lemont, Ill.
Cost: $124 million
Length: 1.3 miles
Type: Precast, post-tensioned concrete bridge
Designer: American Consulting Engineers, Crawford, Murphy & Tilley, V3 Cos. of Illinois, Bollinger Lach & Assoc., Wight & Co.
Owner: Illinois Tollway
Contractor: Walsh Construction Co.
This bridge will rise 90 ft above the ground at its highest point. It is the focal point of a project that will reduce congestion in one of the fastest-growing counties in the U.S. The contractor had to work around several endangered species and work within a limited footprint.
Number 7: Monroe Street Viaduct Replacement, Baltimore, Md.
Cost: $11 million
Length: 850 ft
Type: Continuous steel-plate and prestressed girders
Designer: Gannett Fleming Inc.
Owner: City of Baltimore
Contractor: Joseph B. Fay
The Monroe Street bridge consists of a three-span continuous steel-girder section that crosses over the railroad/light-rail line. The location under a portion of I-95 restricted shifting of the existing roadway. Crews had to deal with poor soil conditions during construction.
Number 8: Perry Street Bridge Replacement, Napoleon, Ohio
Cost: $17.4 million
Length: 724 ft
Type: Earth-filled concrete arch
Designer: HNTB Corp.
Owner: Ohio DOT
The challenge of this project was to construct a replacement bridge at the same location and with a similar appearance to the old concrete barrel arch bridge in one year without disturbing the river bottom between April and July.
Number 9: J.T. Butler Blvd. Interchange and State Road 9A, Jacksonville, Fla.
Cost: $80 million
Length: 5,280 ft
Type: Structural steel box girders
Designer: H.W. Lochner Inc.
Owner: Florida DOT
Contractor: Superior Contractor Inc.
A 2,072-ft-long trestle bridge over wetlands and the Sawmill Slough environmental area is the centerpiece of this job. The bridge will be built on concrete girders instead of embankment. It is 20 ft above the ground and will prevent lasting damage to the wetlands.
Number 10: Fremont Bridge Approach Replacement, Seattle, Wash.
Cost: $30 million
Length: 1,000 ft
Type: Concrete and steel bascule
Designer: Parsons Brinckerhoff
Owner: City of Seattle
Contractor: Mowat Construction
The contractor had to cut a four-lane bridge down the centerline to maintain two lanes of traffic throughout the project. Efforts were made to minimize noise and vibration to sensitive adjacent businesses. Work is being done in confined right-of-way in an old urban setting.