Beam material: Concrete
Max Span Length (ft.): 110
Total Bridge Length (ft.): 223
Construction Equipment Category: Conventional
ABC Construction Equipment: Conventional
State ID Number: 2081
NBI Number: 2081
Latitude: 61.1230011 | Longitude: -100
Bridge DescriptionProject Summary:
on O’Malley Road Eastbound over C Street in the Municipality of Anchorage in southern Alaska
Tier 5 (within 3 months)
Mobility Impact Time:
ABC: 60-day construction of new bridge for extension of a bypass route Conventional: ABC is conventional construction in Alaska
improved site constructability; reduced onsite construction time; improved work-zone safety; improved material quality and product durability; reduced life-cycle cost
223-ft long and 39-ft wide two-span prestressed deck bulb T girder bridge (110 ft – 110 ft)
Average Daily Traffic (at time of construction):
ABC is conventional construction in Alaska due to climate and terrain
Existing Bridge Description:
Replacement or New Bridge:
The bridge has two 11.8-ft-wide traffic lanes (one lane in each direction), an 8.2-ft-wide shoulder, and a 4.3-ft-wide shoulder. The cross-section consists of six adjacent pretensioned decked double-tee girders with 6.5-ft-wide top flange and 4.5 ft depth. The interior pier consists of a cast-in-place concrete pile cap on steel pipe pile extensions. The cast-in-place abutment is founded on steel H-piles.
The girders were fabricated at a precast plant and trucked to the site. The contractor drove the steel H-piles and constructed the cast-in-place abutments, and drove the steel pipe piles and constructed the cast-in-place pile cap. The girders were erected with a truck crane onto elastomeric bearing pads. They were welded to each other at embedded shear connectors spaced at 4 ft along flange edges. Grout was placed in the longitudinal shear keys and the shear connector blockouts between girders. Closure joints at the ends of the girders were cast. Curbs were cast, and metal railing was installed. A waterproof membrane was placed on the deck, followed by an asphalt overlay.This bridge is one of a pair of bridges constructed at this site. These bridges were part of a large roadway project. These bridges were built in about 60 days. They would likely have been opened to traffic sooner, but the bridge subcontractor had to wait for the earthwork to catch up.
This type of bridge is quite common in Alaska. Most are built in one summer construction season – about 5 months maximum. The time is not determined so much for traffic and user impacts but rather for weather and climate limitations. That is, this bridge is not unique in the rate at which they were built — it’s just the way that this style of bridge is built.
High Performance Material:
Precast concrete girders and deck f’c > 7,500 psi
Project PlanningDecision Making Tools:
Project Delivery: Design-bid-build
Geotechnical SolutionsFoundations & Walls:
Structural SolutionsPrefabricated Bridge Elements: Adjacent deck bulb T beams
Prefabricated Bridge Systems:
Miscellaneous Prefabricated: Grouted key closure joints; Grouted blockout w/shear connectors; Asphalt overlay w/membrane
Costs & FundingCosts:
The engineer’s estimate for the entire project was $24.1 million, of which $2.23 million was for the bridge construction (both bridges). The low bid was $27.6 million. There were four bidders. The cost per square foot of bridge was about $130.
Downloadable ResourcesContract Plans:
Other Related Information:
Other Related URLs:
Alaska Department of Transportation and Public Facilities (Alaska DOT&PF)
Elmer Marx, P.E.
Technical Engineer II
Alaska Department of Transportation and Public Facilities