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The 2016 Bridge Award

Prospect Mountain Interchange

NYS Route 17/I-81 over US Route 11 and Chenango River

Project Description

As part of a major reconstruction project in the City of Binghamton, replacement of the NY 17/ I-81 interchange over US Route 11 and the Chenango River, locally known as the Prospect Mountain Interchange, is a demonstration of New York’s commitment to rebuilding its infrastructure. Project objectives included eliminating structural and operational deficiencies and improving safety, but the interchange bridges have become an icon of upstate revitalization. The interchange bridges are constructed using long-span continuous multi-girder curved steel superstructures supported on large hammer-head piers and a combination of conventional cantilever and MSE abutments. Design and construction of the Prospect Mountain Interchange bridges had several unique and complex challenges. Successful completion of this project makes this nominee a strong candidate for recognition.

Notable Factors of the Interchange

$11. Unique Geometry - The highway alignments carried by the bridges included tangents, spirals, and circular curves. Additionally, the bridges had to accommodate the confluence of 2 ramps coming together and emerging as one highway.

$ 2. Complex Superstructure Design - Designed using the AASHTO Load and Resistance Factored Design (LRFD) code this bridge had significant, challenging design hurdles. NYSDOT purchased the MDX software package specifically to perform the analysis and code check involved with this project. This finite element modeling program was used to create a model and run the analysis.

$13. Special Design Features - Stainless steel reinforcement, internal curing concrete, and optional precast alternative made the deck a special feature of these bridges. By reducing the amount of deck cracking and reinforcement corrosion, the designers achieved outstanding long-term deck performance.

$14. Complex Construction Staging - The bridges were designed keeping the traveling public in mind. The project included construction staging allowing all highways passing through the interchange to remain open throughout construction. This was partly accomplished by placing the new bridges on adjacent alignments allowing most of the substructure work to be completed in the first construction season without any impact to traffic.

$15. Aesthetic Details – Because the project site contains 2 publicly accessible areas aesthetics was considered to be a central part of the pier design. A multi-use path runs along the west side of the river and Cheri Lindsey Park is in the southeast corner of the site. As can be seen in the photos below the appearance of the piers from these 2 locations was an important part of the project.Site Plan PMI Rev

The interchange bridges are made up of 6 structurally independent segments, 3 for I-81 NB/ NY 17 WB and 3 for I-81 SB/ NY 17 EB; 2 ramp segments and an overlap segment. The individual ramp segments are separated from the overlap segments by a mid-river modular joint. The adjoining superstructures share the mid-river double pier which supports 2 lines of bearings.

Year 1 Construction Rev

Year 1 Construction looking east – Traffic is maintained on the existing bridges while first segments of the new bridges are constructed on adjacent alignments.

Girder Erection Rev

Girder Erection for NY Route 17 WB – Extensive falsework is used to support the partially completed structure. Construction of this segment is further complicated by the previously erected I-81 SB steel directly below.

Completed Structure 1 Rev

Completed I-81 NB/ NY 17 WB Overlap and NY 17 WB structures looking west from Cheri Lindsey Park – The 2 closest piers are double Piers made to look like 2 adjacent hammerhead piers, matching the individual hammerhead piers supporting the ramp segments beyond.

Completed Structure 2 Rev

Completed NY 17 WB Ramp over I-81 SB Ramp looking west – Detail of the aesthetic piers can be appreciated from the multi-use path along the banks of the Chenango River. The vertical column includes 2 ribbons of horizontal flutes expressing the vertical dominance the bridge has over the site. Additionally, the column elements are wider than the cap, giving their combination the appearance of overlapping elements thereby providing a visual connection between cap and column.

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C/O Mark Olstad
40 British American Blvd.
Latham, NY 12110


Association For Bridge Construction And Design

Eastern New York Chapter