The ordinary transbordeur consists of two towers, an overhead span between them high enough to clear the masts of the tallest vessels, a single track on the span, a car running upon the track, a traveling platform suspended from the car, a fixed platform at each end of the car's travel for unloading and reloading, and approaches to these fixed platforms from the streets. Up to the present time all of the transbordeurs yet built are single-span, single-track, single-carriage, slow-motion structures, consequently their efficiency is low and their use is confined to comparatively narrow waterways.

There are four types of bridge suitable for carrying the cages of the transbordeur, viz., the simple-truss, the continuous-truss, the cantilever, and the suspension. The choice between these will depend almost entirely upon the governing conditions at the crossing.

In "Bridge Engineering" on p. 674 the author in 1916 wrote as follows:

If the author were ever called upon to design a transporter bridge, he would effect a great improvement by widening the structure so as to provide for a double track, and would carry on it four or more cars. These cars would always travel upon the right-hand track, and would run onto a single track at each end of span where they would discharge and take on passengers. Again, he would use powerful electric motors so as to travel at high speed. By these means, the carrying capacity of the bridge would be multiplied many fold and the time required for transit would be reduced to a minimum; because the intervals between cars could readily be made as small as one minute, requiring only sufficient time to unload and reload the foot passengers and vehicles. The car should be made double deck, the pedestrians being carried above; and the roadway should have a double track, the right one being for the use of a single street-car and the left for two, or possibly three, wagons. At the end of the trip the car would leave first, and the wagons would follow immediately, edging over to the right so as to permit of the ingress of the oncoming car, which in its turn would be followed by wagons to occupy the left-hand side. While the vehicles would be going off and others getting on, the upper deck could easily be emptied of its pedestrians and refilled.

At the time the preceding was written the author did not anticipate encountering at all shortly an opportunity to figure upon a transbordeur of the type described; but in 1918 he was selected by the City of New Orleans as bridge expert to serve as one of the three members of the Board of Advisory Engineers specially appointed to study the governing conditions and to report upon the advisability of bridging or tunneling the Mississippi River at or near that city. In the course of the investigations, which occupied nearly a year, there arose the question of building a combined- highway- and- electric- railway structure connecting New Orleans and Algiers. As the line joining the centers of gravity of these two places is below the center of gravity of the cities' wharves, many ocean-going steamers cross it daily, and there will be a still greater number per diem in the future. For this reason a low-level bridge at this location is inadmissible, but a transbordeur layout would undoubtedly be accepted by the War Department, as the resulting structure would interfere very little, if any, with navigation.