As we have said, the subway is 400 yards in length. It has an inside diameter of 10ft. 6in., the footway is 6ft., and there is 7ft. 6in. of headroom. To the extent of this accommodation the tunnel will be able to take horses and vehicles, but it is primarily intended for foot passengers, who will be charged one penny per head, the same as on the chain ferry.

The tube starts just opposite the Mission Church on the dock side, and comes out on the Grangetown side near the petroleum tanks of the Bear Creek Oil Company, on the Ferry-road. At each end is a toll-house with turnstiles, and with a collapsible iron gate for the admission of vehicles. The subway is lighted with electricity throughout, the inside of the tube itself is painted with white enamel, and the approaches lined with white glazed bricks.