For sending workmen inside the siphon to make repairs or clearing away an obstruction there are eight manholes. Four measure 6 by 13 feet, two 6 by 6 feet, and two 6 by 4 feet.
As soon as the Florida Walk canal can be deepened and a few link-ups in the drainage system can be made, the entire drainage of New Orleans, in normal weather and during light storms, will, according to announcement by the Sewerage and Water Board, be sent through this outlet. During the occasional cloudbursts it will be necessary to send some of the drainage into the lake, but this will be rapidly flowing water and will sweep offshore. It means a great deal to the suburban development of the city.
A year and a half the siphon was in the making. Preparations for the structure cost more than $250,000—excavation foundation, etc. The concrete alone cost $170,000. Machinery and the work of housing and installing it cost $60,000 more.
Four bascule steel bridges now cross the Industrial Canal. They are the largest in the city. Three of them—at Florida Walk, for the Southern and Public Belt Railways; Gentilly, for the Louisville & Nashville; and on the lake front, for the Southern, weigh 1,600,000 pounds each—superstructure only. The fourth—at the lock—weighs 1,000,000 pounds. They are balanced by 800-ton concrete blocks and concrete adjustment blocks. Their extreme length is 160 feet; the moving leaf has a span of 117 feet.
With a 30-foot right of way for railroad tracks, 11 feet for vehicles and trolley cars and four feet for pedestrians, they are designed to meet traffic conditions of a great and growing city. They will support 50-ton street cars or 15-ton road rollers—New Orleans has nothing as heavy as that now—and trains a great deal heavier than are now coming to the city. No bridge in the South will support as heavy loads.
The tensile strength of the steel of which the bridges are constructed is from 55,000 to 85,000 pounds to the square inch, and they will bear a wind load of 20 pounds to the square inch of exposed surface.
They are operated by two 75-horse power electric motors, 440 volts, 60-cycle, 3-phase current, which is stepped down from 2,200 volts by means of transformers. In addition, there is a 36-horse power gasoline engine, to be used if the electrical equipment is out of order. To open or close the bridges will require a minute and a half.
THE REMARKABLE LOCK.
Not only is the lock of the Industrial Canal one of the largest in the United States, but its construction solved a soil problem that was thought impossible. That of the Panama Canal is simple in comparison. The design is unique in many respects. The lock is a monument to the power of Man over the forces of Nature, and to the progress of a community that will not say die.