Project Number: 6167, PO #4000061633, Design-Build Services for the Ellison Avenue Bridge Replacement Project
Owner: Long Island Railroad (LIRR)
General Contractor: Posillico Civil Inc.
UHPC Contractor: UHPC Solutions North America
UHPC Supplier:Lafarge Holcim
The Ellison Avenue Design-Build project involved the replacement of a 115-year-old multi-span bridge over the LIRR Main Line in Westbury, NY. The project scope included the design and reconstruction of the bridge from the abutment footings up, including installing a new single-span precast prestressed concrete superstructure with integral wearing surface. Shear Keys for the precast superstructure were filled with 30 CY of 20 KSI UHPC followed by diamond grinding to achieve the final roadway profile. The project was situated in a residential neighborhood, limiting site access and linearizing construction progress.
Construction on the project was challenging because of limited space at the worksite and work over an active commuter rail line main corridor. Design complexities included engineering a new roadway profile that neared maximum permissible grading limits heavy profile in the roadway and engineering a new approach sidewalk and parapet that did not impart additional loads on existing substructures of unknown capacity.
Site logistics and access issues were solved by installing temporary access ramps from the roadway down to the LIRR Right-of-Way below, allowing ease of access to track level for equipment and workers. This also facilitated work during the two weekend outages allotted on the project, for which planning began at the onset of the project to ensure continuity of LIRR operations. Construction means and methods were optimized to minimize work that required track outages, resulting in returning tracks back to service ahead of schedule.
Roadway grading design issues were solved by selecting a shallow precast prestressed concrete beam superstructure, reducing the height of the bridge. The use of a precast superstructure also minimized impacts to LIRR rail traffic below. Helical piles were utilized to transfer loads from a new approach sidewalk & parapet through existing crib-type retaining walls along the bridge approaches, eliminating the need for a costly and intrusive replacement of the crib walls
In total, 30 cubic yards of UHPC were produced and installed during a single casting day. The precast bridge units were prepared for the UHPC material by casting with an exposed aggregate finish which provides an excellent bond with UHPC. Utilization of PBE with UHPC shear keys allowed the shutdown of rail traffic below the bridge to be shortened to two weekend closures. This reduced the impact of the bridge work to a LIRR trains and the traveling public. The use of UHPC joints and PBE also allowed a reduction in the height of the bridge which corrected an existing bridge profile issue.