In order to restore full train service as quickly as possible, MTA Metro-North Railroad crews are working around the clock to make temporary repairs to the railroad’s Park Avenue Viaduct in Manhattan that was damaged by a four-alarm fire underneath the viaduct on Tuesday evening.
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— an announcement Wednesday from Metro-North
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The fire caused structural damage to one steel supporting column and three adjacent horizontal steel girders that run east-west along the width of the underside of the viaduct and are known in engineering terminology as floor beam stringers.
Photos from Metro-North
Because of the structural damage, Metro-North has taken the inside two of the viaduct’s four tracks out of service, and put a speed restriction in place on the two outside tracks.
As a result of the track restrictions, Metro-North is operating on a Saturday schedule until further notice.
Scores of workers from Metro-North’s engineering division are installing six temporary steel columns that will surround the damaged column and connect to it and to one another. Once in place, the seven columns, braced together, will function as a single structure that will bear the weight of the overhead viaduct until permanent repairs can be put in place.
As soon as the temporary repairs are completed, Metro-North will perform structural tests including the impact of train movement over the viaduct. If testing proves successful, restricted speed train service could then resume over the tracks that are currently out of service. The construction and testing process is expected to take 24 to 48 hours to complete.
The fire did not cause any damage to Metro-North’s tracks, signals, or third rail power systems. The damaged column, located near the centerline of the viaduct, is an older, multi-piece “built-up” column design notable for its lattice-like steel appearance; portions of the column date to the initial construction of the viaduct in the 19th century. Columns on the east and west sides of the viaduct, which were put in place by Metro-North in the 1990s, are a newer design consisting of single monolithic blocks; they were not damaged by the fire.