State: AK
County: Sitka (borough)
Owner: State
Location: Rural
Spans: Three-span
Beam material: Concrete
Max Span Length (ft.): 59.3
Total Bridge Length (ft.): 178
Construction Equipment Category: Conventional
ABC Construction Equipment: Conventional
State ID Number: 1491
NBI Number: 1491
Coordinates
Latitude: 57.955 | Longitude: -136.225
Bridge Description
Project Summary:5-week construction of replacement bridge to access island
Project Location:
On Chichagof Island approximately 80 miles west of Juneau in southeast Alaska
Impact Category:
Tier 5 (within 3 months)
Mobility Impact Time:
ABC: bridge constructed in five weeks
Conventional: ABC is conventional construction in Alaska
Primary Drivers:
Reduced onsite construction time; improved site constructability; minimized environmental impacts; reduced life-cycle cost
Prefabrication provided the Alaska DOT&PF with a new bridge with a longer service life and lower maintenance costs, and it facilitated safe construction in a sensitive environment. Total prefabrication improved constructability for the construction crews and reduced labor costs. Residents of the island got a new bridge quickly constructed and strong enough to support their civic vehicles.
Dimensions:
178-ft long and 19.08-ft wide three-span decked adjacent double-tee beam bridge (59.3 ft – 59.3 ft – 59.3 ft)
Average Daily Traffic (at time of construction):
100
Traffic Management (if constructed conventionally):
ABC is conventional construction in Alaska due to climate and terrain.
Existing Bridge Description:
Built in 1992, the old one-lane timber bridge was structurally deficient and required rapid replacement to allow access for the small fishing community’s new fire truck.
Replacement or New Bridge:
The new one-lane bridge consists of precast, pretensioned decked double-tee girders with precast pier and abutment caps on steel H piles. The superstructure cross-section consists of three adjacent 6.33-ft wide 2.67-ft deep girders with timber railing.
Construction Method:
Construction requirements included staying out of the sensitive creek bed and completing work within a short time defined by the Department of Fish and Game. The Alaska DOT&PF chose a totally prefabricated bridge with all material, including rock for the approach fill, barged to the work site.
The contractor floated in barges at high tide and anchored them in the creek. Crews drove the steel H piles from barges, drove a large-wheeled crane onto the barges, and then used the crane to install the caps. Cap pockets were filled with concrete. The crane was then used to erect the decked double-tee girders. The midspan diaphragms were then post-tensioned with 1-inch-diameter bars. No heavy equipment was lodged in the creek bed.
Stakeholder Feedback:
High Performance Material:
Project Planning
Decision Making Tools:Site Procurement:
Project Delivery: Design-bid-build
Contracting:
Geotechnical Solutions
Foundations & Walls:Rapid Embankment:
Structural Solutions
Prefabricated Bridge Elements: adjacent T beam (double tee), precast pile cap, precast abutment capPrefabricated Bridge Systems:
Miscellaneous Prefabricated: PT ducts/bonded, socket connection (in precast substructure)-(caps)
Costs & Funding
Costs:The engineer’s estimate for this project was $219,000. The low bid was $296,000 ($77,000 = 35% higher than engineer’s estimate). There were three bidders. The cost per square foot of bridge was $87.
Funding Source:
Federal and State
Incentive Program:
Additional Information
Downloadable Resources
Contract Plans: View AK-PelicanCreek1491_As-BuiltBridgePlans.pdf
View AK-PelicanCreek1491_Special-Provisions.pdf
View AK-PelicanCreek1491_BidTabs.pdf
Other Related Information:
AASHTO TIG/FHWA Prefabricated Bridges 2004, Good Business – Best Practice
Other Related URLs:
Contacts
Owner:
Leslie Daugherty, P.E., S.E.
Chief Bridge Engineer
Alaska Department of Transportation and Public Facilities
leslie.daugherty@alaska.gov
907-465-8891