Although the bridge was constructed with only one 6-lane roadway, Ammann had provided extra trusses to support a potential second roadway underneath the main deck. These trusses, which were used to strengthen the bridge, were a design alteration that was added to many bridges in the aftermath of the Tacoma Narrows Bridge collapse in 1940. The Verrazzano-Narrows Bridge became so popular among motorists that in March 1969, the TBTA decided to erect the lower deck at a cost of $22million. The Verrazzano Bridge had not been expected to carry enough traffic to necessitate a second deck until 1978, but traffic patterns over the previous five years had demonstrated the need for extra capacity. By contrast, a lower deck on the George Washington Bridge, connecting New Jersey and Upper Manhattan, had not been built until thirty-one years after the bridge's 1931 opening. The new six-lane deck opened on June 28, 1969. Originally, the Verrazzano Bridge's Brooklyn end was also supposed to connect to the planned Cross-Brooklyn Expressway, New York State Route 878, and JFK Airport, but the Cross-Brooklyn Expressway project was canceled in 1969.