Rapallo Viaduct was leased in 1879 to the New York, New Haven, and Hartford Railroad and later was proposed to be encased as its capacityhad become inadequate.
After a few years of attempted competition, it was leased by the New York, New Haven and Hartford Railroad in 1879, which was the operator of the viaduct thereafter. By the early 20th Century, the iron viaduct's capacity was inadequate for the New Haven's heavier freight trains, and in 1911, the New Haven submitted to the state railroad commissioners a plan to encase Flat Brook in a culvert and fill in the viaduct. 
