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crossings will sooner or later alter the existing approaches in such a manner that the resulting gradients would not be further increased by raising the bridges. It is to be noted, however, that the precise elevations recommended by the local office of the United States Engineers for these bridges would involve serious complications with the railroad tracks.

In many cities having similarly situated level business and manufacturing districts along rivers, very large sums of money have been spent to reduce the gradients on the connecting bridges to less than 3 per cent, and that figure is rather generally regarded by engineers as a maximum upon important traffic bridges.

People in Pittsburgh are so accustomed to steep gradients in the adjacent hill districts that they are apt to ignore the fact that there is a city within their city, and that this inner manufacturing and business city is closely confined to the long drawn-out, irregular, level river-bottoms and is much freer from hills than New York, almost as much so as Chicago.

The city has expressed its willingness to spend a large sum of money and undergo great inconvenience for the sake of a moderate reduction in the street gradients of the "Hump" at one of the gateways of the hill districts. Important as this work is, it cannot be compared for a moment as a matter of traffic improvement with the importance attaching to easy gradients on the bridges, for the streets of the "Hump" district lead in the main from the Hat part of the city to the hilly part where average loads are limited by the prevailing steep gradients, whereas the bridges lie between two parts of the level industrial and commercial city. If at low gradients they serve to unite them, if at high gradients they divide them.

Railroad Bridges. -- In so far as any changes in the railroad bridges produce conditions less convenient and expeditious for handling the business which the people have to do with the railroad, the public has a direct concern in the matter.

With regard to the Junction Railroad bridge of the Baltimore and Ohio Railroad System, the raising proposed by the local office of the United States Engineers, appears to involve no serious difficulties in operation which would affect the general public or the shippers.

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