In 1940, work started on the Brooklyn–Battery Tunnel, which passes underwater offshore of the island's northeast corner. A ventilation building designed by McKim, Mead & White is connected to the island by a causeway. Initially, Triborough Bridge and Tunnel Authority chairman Robert Moses had proposed a bridge across the harbor, but the War Department quashed the plan, calling it a possible navigational threat to the Brooklyn Navy Yard located upriver. A subsequent plan to build a ramp from Governors Island to the bridge was rejected as well. The Brooklyn–Battery Tunnel opened to traffic in 1950 without any other physical connection to the island.