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the car tracks. About 7 feet over all is now the ordinary maximum in Pittsburgh, a few auto trucks and delivery vans exceeding that figure slightly, and an occasional three-horse team occupying over 8 feet. In New York and Boston, wagons measuring from 7 to 8 feet from hub to hub are common, and they sometimes considerably exceed 8 feet.

Just as in the case of steam and electric railway equipment, the tendency is constantly in the direction of heavier, longer, wider vehicles, for the sake of the operating economy due to large units; and, with the steady increase in the use of motor vehicles for business purposes, this tendency is likely to be greatly accelerated. There is every reason to expect that motor trucks will gradually increase in size until a limit is fixed by the public authorities in order to protect the pavements, and for the sake of standardizing the lines of travel in relation to the street widths. But, in the interests of economy of operation, the limit should be as high as practicable, probably not less than 8 feet.

If 8 feet be allowed for each vehicle, plus only a foot of clearance, the cars and one row of vehicles on each side, between them and the vehicles standing at the curb, would require 54 feet between curbs. A wagon backed up to the curb on a busy street will seriously discommode travel at that, and the clearance allowed is very small. A width of 54 to 60 feet between curbs is, therefore, highly desirable in the main thoroughfares.

As a matter of fact, with the widths of vehicles which now prevail in Pittsburgh, if standing and slow-moving vehicles are compelled to keep in contact with the curb, it is possible to keep open a line of travel on each side of the car tracks, with only occasional blockades, where the width between curbs is 50 feet, or, at a pinch, even 48 or 47 feet. That is to say, the difference in traffic capacity between a thoroughfare 50 feet from curb to curb and one 45 feet is enormous; while the difference between 45 feet and 40 feet is very slight.

Since a main thoroughfare is apt in time to become a retail trading street, wide sidewalk space is important. It is a common rule to make the distance of the curb from the property line one-third the width of the roadway.

A total width of 90 feet, with a 54-foot roadway and 18-foot sidewalks, is a satisfactory minimum for meeting the practical

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