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Fostering Innovation Interstate Route H-1 Viaduct Improvements
2.1. Project Overview
HDOT has proposed improvements to three viaducts - the Pearl City Viaduct, the Waimalu Viaduct and the Airport Viaduct - located within the Ewa and Honolulu districts on the island of Oahu, Hawaii.
The project spans Interstate H-1 from Waipahu (milepost 8.8) to the Honolulu International Airport (milepost 18.1). Collectively, the three viaducts comprise nearly four miles of the nine-and-a-half-mile corridor.
Figure 1: Project Area
The scope of work for the Interstate Route H-1, Pearl City, Waimalu and Airport Viaduct Deck Improvements project is to provide a repair method that will address the deteriorating deck surface of the three viaducts. Ultimately, HDOT's goal is to find a long-term (50-year) solution that will prolong the life of the three structures without crippling traffic along some of the State's most heavily used roadways.
Pearl City Viaduct
The Pearl City Viaduct is an American Association of State Highway and Transportation Officials (AASHTO) girder bridge with a total length of approximately 1.1 miles. It is located between Waiawa Interchange and Waiau Interchange and extends from the Sears Distribution Center building where H-1 crosses over Kamehameha Highway to the Waipahu off-ramp. It was constructed between 1968 and 1970 under four separate contracts.
The superstructure comprises 62 spans of precast, pre-stressed concrete AASHTO girders spaced at five feet, four and a half inches to support an approximately six-and one-half-inch-thick reinforced concrete deck. The eastbound and westbound roadways are actually two independent structures, each 69 feet, eight inches wide.
The substructure of both the Pearl City and the Waimalu Viaducts comprises reinforced concrete piers of multi-circular column frames supported on 16-inch pre-stressed concrete piles.
The Waimalu Viaduct is an AASHTO girder bridge with a total length of approximately 0.3 miles. It is located between Waiau Interchange and Halawa Interchange and crosses over Kaahele Street, Waimalu Stream and Pono Street near the Moanalua Road intersection. The construction of Waimalu Viaduct was completed in 1970 under a single contract.
The superstructure consists of 12 spans of precast, pre-stressed concrete AASHTO girders spaced at five feet, four and a half inches to support a six-and one-half-inch-thick reinforced concrete deck. The total bridge width is 138 feet and four inches.
The Waimalu Viaduct is currently being widened in the westbound direction between the Kaonohi Street overpass and the Pearl City off-ramp. The widening will provide a total of six continuous westbound lanes between Halawa Interchange and the Pearl City off-ramp. In addition, shoulder widths will be brought up to current Interstate standards. The widening is expected to be completed in June 2006.
The Airport Viaduct is a tee-girder bridge with a total length of approximately 2.3 miles. It is located between Pearl Harbor Interchange (Valkenburgh Street) and Keehi Interchange and includes the Airport Interchange, which provides access to the Honolulu International Airport, Rodgers Boulevard and Paiea Street. The Airport Viaduct is constructed over Nimitz Highway, which runs parallel to and directly beneath the viaduct. The Airport Viaduct was constructed under multiple contracts and completed in 1981.
The superstructure consists of 111 spans of precast, pre-stressed concrete tee-girders laid side by side to support a six-inch-thick reinforced concrete composite topping. The two half-sections are separated and symmetrical about the centerline.
The substructure comprises reinforced concrete piers of two rectangular-legged rigid frames supported on weathered rock foundations. Planter boxes were installed on top of the inside legs of the rigid frame for landscape planting.
2.2. Project History and Development
KSF, Inc. documented the deteriorating deck conditions along the project corridor in their July 2003 Project Assessment Report on the Pearl City Viaduct:
Deterioration of the top surface of the bridge deck has been an ongoing maintenance problem. Potholes initiated by spalled concrete are located throughout the length of the viaduct and are severe in several concentrated areas.
KSF, Inc. attributes the spalling of the top surface to "corrosion of the top layer of reinforcing steel." The corrosion, meanwhile, was caused by a number of factors, including insufficient cover, cracks, carbonation, high levels of chlorides, tining and simple concrete fatigue. Overall, KSF notes, the viaduct is still structurally sound.
Because Hawaii's climate plays a major factor in long life pavement maintenance, HDOT has initiated a research project on the Waimalu Viaduct. The goal of the study, which is being conducted in conjunction with the current widening project, is to find a long-term solution to deck deterioration on the Interstate viaducts.
The research project will evaluate five proprietary high-performance concrete (HPC) overlay materials: Quikrete, MasterBuilders Set 45 HW, SikaSet Roadway Patch 2000, Sinak Relay and Tamms Express Repair Rapid Hardening Mortar. Besides allocating a specific section of the viaduct to each product, HDOT will be utilizing special surface preparation methods (shot blasting and hydro-demolition) as appropriate for each HPC. The HPCs will then be monitored for five years to assess their performance under local environmental conditions.
2.3. Project Challenges
The primary challenge for the Interstate Route H-1, Pearl City, Waimalu and Airport Viaduct Deck Improvements project is to accomplish the work within severe time constraints. This corridor experiences extremely heavy traffic volumes during the morning and afternoon peak periods (see traffic data below), and it is common to see backlogs throughout the day and on weekends. Therefore, minimizing traffic disruptions and providing reasonable continuity of traffic during construction operations are of paramount concern.
PEARL CITY VIADUCT
Projected traffic volumes were obtained from the Oahu Metropolitan Planning Organization (OMPO). OMPO's data does not represent actual traffic counts; rather, it represents forecasts based on population and employment projections from census data.
HDOT anticipates that the majority of the repair work will occur during the overnight hours on weeknights and, possibly, on weekends.
2.4. Project Status
Rehabilitation of the Pearl City and Waimalu Viaducts is scheduled to begin in FFY 2007 and be complete in FFY 2011. Estimated project cost is $50 million.
The Airport Viaduct portion is not yet programmed, in large part due to funding constraints - the estimated rehabilitation cost is $50 million. HDOT plans to let a short-term repair contract in 2006.