The City of New Orleans for many years has had under consideration the building of a combined railway and highway bridge across the Mississippi River; and within the last few years the project has been seriously contemplated.

Some two decades ago the late Collis P. Huntington, President of the Southern Pacific Railway Company, and his consulting engineer, the late Dr. Elmer L. Corthell, made an investigation of the scheme of building at that place a double-track railway bridge; and they called in as advisory engineers the author and his brother, Montgomery, to estimate upon the cost of a low bridge. The death of Mr. Huntington, which occurred shortly afterwards, caused the project to be dropped; and it was never revived. The author's joint study was made with considerable thoroughness. It involved the solution of two or three problems of great magnitude that were new to the engineering profession, the principal economic one being a comparison of costs of a high bridge and a low bridge. The result was decidedly in favor of the latter.

The problem now facing the city, however, is much more complicated, involving, as it does, a combination of steam-railway, electric-railway, vehicular, and pedestrian traffics. There is a choice between two locations, one near the center of the city and the other several miles further upstream—in fact, some intermediate locations might have to be considered. There is a sentiment among certain prominent citizens favoring a tunnel rather than a bridge; and, on that account, the question of bridge versus tunnel will have to be considered, notwithstanding the fact that the difficulties presented by the tunnel proposition are almost insurmountable in view of the present status of engineering knowledge and experience.

The question of high-bridge versus low-bridge will have to be thoroughly thrashed out in order to please the public, although any truly-experienced engineer would determine very quickly in favor of the latter, irrespective of the possible opposition of the river interests and even that of the War Department.

The economic method of handling the combination of the various kinds of traffic would require some study to determine; and the best method might vary with the location of the structure.

The style and dimensions of the moving span—whether swing, bascule, or vertical lift—and the sizes of the clear opening or openings are mooted points involving a consideration of economics and other important matters. This question is complicated by the fact that the requirements ought to be dependent on the location; because at the upper one there would be very few vessels passing, while at the lower one there would be many.

The unprecedented depth for the pier foundations involves an economic study in order to ascertain the best method of sinking and founding.

The facilities for freight, passenger, and vehicular traffic afforded by