In the face of criticism, Roebling completed the project in four years, using Ellet's bridge as scaffolding. The railway deck was stress-tested by the crossing of the steam engine "London" at a speed of on March 8, 1855. Ten days later the upper deck of the bridge was officially opened; the lower deck had been opened to the public a year earlier. As the first commercial passenger train trundled over the bridge, the two countries were finally connected by railroad across the Niagara River. The successful crossings of these and later trains made Roebling's Suspension Bridge the first working suspension railway bridge in history.