By Rick Donohue
The presentation at the March 26th meeting of the Retired Men’s Association detailed the extensive repair project undertaken in the Canarsie Tunnel after it suffered significant damage from flooding during Superstorm Sandy in 2012. The tunnel, which carries the L train between Manhattan and Brooklyn, was inundated with seven million gallons of salt water from the East River, leading to corrosion of the concrete bench walls and damage to critical infrastructure like tracks, signals, and electrical equipment. Isabel
Lopes, a structural engineer at WSP, explained how an initial plan for a prolonged shutdown was averted, and the repairs were completed while maintaining partial operation.
The original repair strategy proposed an 18-month full closure of the L train to allow for the complete replacement of the damaged concrete bench walls, the track bed, and the rails. This plan, however, generated considerable anxiety among local residents and businesses who relied heavily on the L train for commuting and commerce. To mitigate these concerns, the MTA developed an alternative service plan involving busways, ferries, and increased service on other subway lines. Unexpectedly, in January 2019, Governor Cuomo announced the cancellation of the full shutdown, mandating that the repairs be executed within a compressed 15-month timeframe while keeping the tunnel operational. This abrupt change necessitated a fundamental rethinking of the repair methodology. To address this challenge, a group of experts from Cornell and Columbia engineering was convened to reassess the project goals and propose a revised approach aimed at minimizing disruption to passengers. Simultaneously, Isabel Lopes and her design team were tasked with inspecting the tunnel to develop a feasible repair plan that could be implemented under these new constraints.
A crucial step in the revised plan involved a detailed inspection of both tubes of the Canarsie Tunnel. Engineers, contractors, and MTA representatives walked the entire length, assessing the condition of the concrete bench walls in 10-foot increments. They used hammers to sound the concrete and visually inspected for cracking and spalling, categorizing each segment into one of three conditions: good condition (no action needed), some damage (requiring local strengthening), and severe damage (slated for removal).
Based on this assessment, the original plan for full demolition and reconstruction of the bench walls was modified. Instead, the revised approach incorporated local strengthening using rigid Fiber Reinforced Polymer (FRP) panels for all damaged areas. These panels offered a multi-purpose solution, serving as a walking surface for emergency egress and maintenance, spanning over removed sections of the bench wall, and even incorporating rungs and grab bars in some designs. The FRP panels were constructed from a phenolic resin (historically known as Bakelite) reinforced with glass fibers. Extensive engineering analysis, including deflection tests with personnel jumping on a mockup panel and finite element analysis, was conducted to ensure the panels’ structural integrity under various loading conditions, such as pedestrian traffic and potential impact from a collapsing bench wall. The management of electrical cables also underwent a significant change. The initial plan to embed new cables within reconstructed bench walls was discarded. Instead, the existing damaged cables were abandoned in place, and a new cable management racking system was installed on the tunnel’s concrete liner above the bench walls. This approach, common in other modern tunnel systems worldwide, allows for easier access to the cables for future maintenance, repairs, and replacements.
For the tracks, a similar strategy of localized repair was adopted. Instead of fully replacing the concrete track bed and rails, the existing ties were locally cut out and replaced with more corrosion-resistant composite ties, followed by localized concrete pouring to secure them. The rails were then replaced during weekend closures.
To ensure the long-term safety and functionality of the repaired tunnel, a fiber optic cable monitoring system was implemented. This system continuously monitors both the existing concrete bench walls and the newly installed FRP panels for any signs of movement or deterioration. If cracking or a local collapse occurs, the fiber optic cable detects the movement and immediately transmits a signal, allowing for prompt intervention and necessary repairs.
The revised repair plan proved highly successful.
The work requiring shutdowns was completed in just 12 months, three months ahead of the accelerated schedule. This achievement minimized disruption for the approximately 250,000 daily L train riders. The project exemplified a collaborative spirit among the MTA, WSP, and the contractor, driven by the urgency and the need for innovative solutions. The methods employed, particularly the use of FRP panels and the cable racking system, have since been considered for other infrastructure repair projects.
The project was funded through a combination of FEMA funds, MTA funding, and state funding, and the efficient execution of the revised plan resulted in cost savings compared to the original full shutdown proposal. Regarding the broader resilience of the New York City subway system to future flooding events, various measures are being implemented. These include the installation of curbs at subway station entrances to impede surface water runoff and the potential consideration of guillotine-style floodgates within tunnels to prevent catastrophic flooding. The PATH train, which also experienced severe flooding during Superstorm Sandy, underwent its own repair process, with methods tailored to its specific infrastructure, including its power system. The Canarsie Tunnel project serves as a valuable case study in effectively and efficiently repairing critical infrastructure after a major disaster while minimizing disruption to the public.
The talk can be viewed by going to the RMA website at https://greenwichrma.org, and clicking on “Speakers.”
The RMA’s upcoming presentation, “Frederic Church’s Olana” by Carolyn Keogh, is scheduled for 11 AM on Wednesday, April 9, 2025. Note: This and all future RMA presentations will be held at Christ Church Greenwich, Parish Hall, 254 E. Putnam Avenue, Greenwich, CT 06830.
Frederic Edwin Church (1826-1900) was one of the leading American landscape painters of the 19th century, and a central figure in the Hudson River School of painters. His masterwork was Olana, a sprawling estate near Hudson, NY, boasting an eclectic mansion with spectacular views of the Hudson River and the Catskill Mountains. It has been designated a National Historic Landmark. In this lecture Carolyn Keogh will examine Church and his artist-designed house and surrounding landscaping through the lenses of art, ecology, and place.
Carolyn will discuss how deeply rooted Olana and Church’s practice is in the inspiration of place, discuss Church’s engagements with the emerging field of ecology in the 19th century and explore his four-decade-long development of Olana as a work of three-dimensional landscape design.
Carolyn Keogh is the director of education and public programs at The Olana Partnership where she oversees programs for diverse learners of all ages at the renowned landmark historic site. Previously, she managed school, youth, and teen programs at the Guggenheim Museum. She has presented at conferences on intergenerational art and technology programs and on inclusive farm interpretation and is a member of the New York City Museum Educators Roundtable. Her scholarship on empathy-building, art museum education, and public programming was published in “Theory and Practice” in 2019 and “History News” in 2022. Carolyn received her BA from NYU in art history and an MA in art history with a focus on art museum education from City College.
To stream the presentation by Carolyn Keogh at 11 AM on Wednesday, April 9, click on https://bit.ly/30IBj21. This presentation will also be available on local public access TV channels, Verizon FIOS channel 24 and Optimum (Cablevision) channel 79. The public is also invited to attend the presentation in person at Christ Church Greenwich, Parish Hall, 254 E. Putnam Avenue.
Note: The views expressed in these presentations are those of the speakers. They are not intended to represent the views of the RMA or its members.
RMA speaker presentations are presented as a community service at no cost to in-person or Zoom attendees, regardless of gender. Any member of the public who would like to receive a weekly email announcement of future speakers should send a request to members@greenwichrma.org. The RMA urges all eligible individuals to consider becoming a member of our great organization, and thereby enjoy all the available fellowship, volunteer, and community service opportunities which the RMA offers to its members. For further information, go to https://greenwichrma.org/, or contact info@greenwichrma.org.
