Footways are not required to bear the heavy loads which come upon the roadway pavement, but in streets of considerable travel are subjected to a continual abrading action, and for good service are required to be of a material which will resist abrasion well, of so uniform a texture as to wear evenly, and not hard enough to become smooth and slippery in use.
A good sidewalk should always present an even sur face, and therefore requires a firm foundation to resist the displacement of the blocks of which it may be com posed. It must also be durable under atmospheric changes, and of material that may be easily cleaned. The materials commonly employed are gravel, wood, brick, asphalt, stone, and concrete.
Gravel walks are the cheapest of footways where suitable material is available. They are constructed in a manner similar to that used for gravel roadways, and require that the bed of the walk be well drained, and that it be well compacted by rolling or ramming before the walk is placed upon it. The best gravel walks are usually built upon a base of rough stone. This base may be 6 or 8 inches thick, and forms a solid founda tion upon which the gra vel surface may be placed and sustained against settling. Walks constructed in this manner are frequently used in city parks where the travel is considerable. On suburban roads gravel walks usually consist of a thin surface of gravel laid upon the earth-bed, and are replaced by some other surface when a more expensive construction can be afforded. Gutters are frequently necessary to protect the walk from the wash of surface-water, which other wise very quickly destroys it.
Wood is commonly used for walks in the form of planks which are laid on stringers, the planks being placed perpendicularly to the direction of travel. It is comparatively short-lived, and requires considerable expenditure for repairs, as the material is perishable and also wears rapidly.
Brick footway pavements have been extensively used for many years, and form, when well constructed, a very durable and satisfactory sidewalk. As commonly con
structed they consist of ordinary hard-burned bricks laid flat upon a layer of sand over the earth-bed. For light travel, pavements so constructed may last well and give good service; but they are apt to soon become uneven through the sinking of the bricks because of in sufficient foundation.
In constructing such a pavement the sand layer should be well compacted by rolling or ramming be fore setting the bricks, which should also be rammed to a firm and even bearing. To give satisfactory re sults a foundation of sand and gravel or broken stone should be formed 8 to 10 inches in thickness. In Washington a layer of gravel 4 inches thick and well compacted is used, with a layer of sand of the same thickness upon it to receive the surface. In forming the pavements, the bricks are laid flat and as close as possible. The joints are filled with sand, usually by coating the surface with a layer of sand before ram ming and after completion a second coating, which is allowed to remain a few days after admitting the travel to it.
Care must be used in selecting brick for this purpose to get only hard-burned brick of uniform quality, in order that the resistance to wear may be even. The use of vitrified paving brick, as used for roadway pavement, would be of advantage on walks subjected to heavy wear.
The use of a concrete foundation and setting the brick on edge and in mortar, after the manner of con structing a roadway pavement, makes a very durable sidewalk under heavy travel. It is, however, some what expensive, and usually a stone surface would be preferable where such expense is to be incurred.
Footway pavements of a concrete in which coal-tar is the binding material have been widely used, but have not usually been satisfactory in use. As commonly constructed they wear rapidly and soften, becoming very disagreeable in hot weather. Some pavements of this character have, however, shown fairly good service.