Though tolls had been instituted for carriages and cable-car customers since the bridge's opening, pedestrians were spared from the tolls originally. However, by the first decade of the 20th century, pedestrians were also paying tolls. Tolls on all four bridges across the East River—the Brooklyn Bridge, as well as the Manhattan, Williamsburg, and Queensboro bridges to the north—were abolished in July 1911 as part of a populist policy initiative headed by New York City mayor William Jay Gaynor. The city government passed a bill to officially name the structure the "Brooklyn Bridge" in January 1915. Ostensibly in an attempt to reduce traffic on nearby city streets, Grover Whalen, the commissioner of Plant and Structures, banned motor vehicles from the Brooklyn Bridge in 1922. The real reason for the ban was an incident the same year where two cables slipped due to high traffic loads. Both Whalen and Roebling called for the renovation of the Brooklyn Bridge and the construction of a parallel bridge, though the parallel bridge was never built.