More than 55,000 tons of steel were used, as well as 18,122 m³ of granite and over eight million rivets. The bridge has a speed limit of 50 mph (80 km/h) for passenger trains and 20 mph (32 km/h) for freight trains. The weight limit for any train on the bridge is 1,422 tonnes (1,442,000 kg). Approximately 4,600 workers were employed in construction of the bridge.