Hurricane Ida caused flash flooding of the Metro-North Hudson Line rail in September 2021, resulting in the partial collapse of the 100-year-old Wicker’s Creek culvert at milepost 21.16 and knocking all four tracks out of service. The team provided an immediate emergency response that included interim repair to the westernmost tracks and then replaced the culvert.

The team’s design firm developed preliminary sketches, drawings, draft specifications and boring logs for the culvert replacement within two weeks of the collapse. This information allowed the general contractor to quickly procure steel rolled shapes, reinforcement material and micropiles, which were chosen because they could be obtained in an expedited time frame.

Photo courtesy HNTB Corp.

The design is a three-sided box concept consisting of independent filler beam superstructures that were made integral with stemwalls at each end. The work was performed using a staged approach, replacing one track at a time. The first two tracks were finished within two months, and all four were completed by the end of March 2022.

The new structures were designed to achieve a 100-year service life and to meet modern loading criteria—using high-strength, high-performance concretes and fracture- and fatigue-resistant steels, which are durable and maintenance-free. All placed concrete used a self-consolidating high early mix. The filler beams could be lifted individually with light duty rail mounted equipment or all at once, allowing for rapid replacement to reduce impacts to the traveling public. They were made with A709 grade 50 steel with a three-coat paint system on the bottom flange of the beam structure.

Photo courtesy HNTB Corp.

The project also focused on improved hydraulic characteristics in case of future hurricanes or floods. The structure bottom is above the measured high tide water level, and the wider clear opening reduces headwater elevations for every studied storm event.

The emergency culvert replacement is expected to have reaching impacts. Metro-North is conducting hydraulic studies on water crossings along its Hudson and Harlem lines to identify vulnerabilities and is planning over the next two years to perform a systemwide evaluation to assess flood risk to 40 undergrade bridges.

Photo courtesy HNTB Corp.

It is anticipated that at least three structures will be found in need of replacement—and the filler beams used for the Wicker’s Creek culvert could be an ideal solution for the future projects, the team says. The $7.5-million project finished at budget and ahead of schedule in seven months.