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be provided as at present, but in a more decent and commodious style.

This section is of a type tested by practical experience and is clearly a great improvement upon the present primitive conditions. But it is open to two objections: first, that the quay is flooded at intervals, although so designed as to suffer no injury and to be put out of commission only when the river is practically closed to navigation by the height of the flood; and, second, that at low water, that is to say "pool full," it is not at the most convenient height.

An alternative section is therefore suggested, which has less precedent behind it, but which might prove better adapted to the Pittsburgh conditions. In this the fixed level of the commercial quay is replaced by a continuous landing stage formed of long floats or barges, of permanent construction, moored against the wall and free to rise and fall with the changing level of the river. The approaches to the floating quay for wagons would be, as in the case of the fixed quay, by descending inclines parallel with the river just outside the main wall; but in this case the roadway would be formed by a line of barges which would rest on a fixed incline during low water. The rising water would lift the barges off the incline successively, beginning with the lowest, so that at all stages of the water they would maintain an uninterrupted roadway to the quay on a proper gradient. Successful precedents for such use of permanent floating quays, and of alternately floating and grounded driveways to the landing stage, are to be found in Italy and in the recent harbor developments at Manaos, Brazil.

A great advantage of the floating quay is that in this type of construction the bed of the river may be excavated to its full depth back to the face of the flood wall itself, and that the space necessary for the commercial quay is secured on the floating structure outside of this line without materially reducing the prism, or section, of the flood discharge. It would therefore be possible, with this design, to secure more ample width for street, for promenade, and for commercial quay, and at the same time have more space in the river for the passage of the floods.

Whatever may prove to be the best details of the river-front treatment, it is clear that it can and should provide an ample

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Last modified on 22-Dec 1999
Design format: copyright 1997-1999 Bruce S. Cridlebaugh
Original document: Frederick Law Olmsted, 1910