—Noisiness is a real source of disease, especially mental disorders. The less noisy types of pavement are usually laid in front of hospitals.
Acceptability.
—The acceptability of a roadway depends in addition to the things mentioned on its looks, appearance, esthetics; on the degree of heat and light which it reflects; upon its springiness and comfortableness to travel over as well as its easiness upon horses’ feet and rubber tires.
© Underwood and Underwood
CROWNING A CALIFORNIA DIRT ROAD WITH TRACTOR DRAWN GRADER
Some Types of Roads and Their Qualities.
—Earth Roads.—The good qualities are: low first cost, not slippery, noiseless, easy on horses’ feet and on rubber tires, comfortable when in first-class condition. The poor qualities are: high tractive resistance, not durable, high cost of maintenance when traffic becomes dense, requiring constant attention to be kept in good condition, difficult to clean, muddy in wet weather, dusty in dry weather, choppy when dust blows away, rut easily, wear down rapidly under heavy traffic especially in windy localities, uncomfortable except when in prime condition. Adaptability: Satisfactory for light or medium traffic when properly drained and constantly maintained. It will probably pay to put in better roads when the traffic amounts to more than 400 vehicle-tons per day.
Sand-clay Roads.—The good and poor qualities are about the same as for earth roads. In fact they are earth roads with a selected mixture of sand and clay. They are more durable, harder and smoother than the ordinary earth road. They are appropriate for a light or medium traffic and are especially adaptable for sandy stretches or over clay or gumbo soils. The cost will depend upon the availability of materials; the cost of maintenance should be no more or very little more than earth roads. They should be good up to 800 vehicle-tons per day.
Gravel Roads.—The good qualities are: moderately hard, compact, and smooth, not slippery, noiseless, easy on horses’ feet, and not very hard on tires, not muddy, are comfortable, and low in first cost. Poor qualities: rut rather easily and require constant attention to keep them in first-class condition, dusty in dry weather. Gravel sometimes becomes loose on top and rolls under fast moving vehicles, causing skidding. When not thoroughly compacted gravel roads have high tractive resistance. They are particularly well adapted to country roads under medium traffic, especially where gravel may be obtained at a reasonable cost near at hand. At the present time more miles of gravel roads than of any other type of surface are being constructed in the United States. This is because of their low first cost and general satisfactory character for medium traffic.