The shoulder is a portion of the roadway contiguous with the traveled way for accommodation of stopped vehicles for emergency use. It is desirable to provide shoulders on all heavily traveled roadways. However, because of the high cost of land and heavy pedestrian use, it is not practical to use them on urban streets. They are always used on freeways, but they should also be used on major and secondary highways in rural areas and on bridges and other structures.
Where shoulders are used, the normal width of shoulder should be carried throughout the entire project length. These shoulders should be paved sections like parking lanes on major streets but should be reserved for emergency use.
On some arterial streets, it is desirable to provide mountable shoulder curbs at the edge of the traveled roadway. These curbs assist in the delineation of the through pavement, form an essential part of the surface drainage system, function as a transition strip between pavement and shoulder, and reduce shoulder maintenance.
When flush with the pavement, shoulders should then be superimposed at the points where the existing be pitched sufficiently to remove surface water from the pavement areas, but not so steeply that vehicular use at anticipated speeds is hazardous. The normal slope for paved shoulders is 0.25-inch per foot. On the high side of superelevated sections or where the shoulder slopes in the opposite direction from the pavement, too great a cross-slope grade break between the traveled roadway and the shoulder should be avoided. The algebraic difference in cross-slope should not exceed about 0.07 foot per foot.
Where shoulders are required, the minimum width should be 8 feet. When drainage requirements dictate, and when additional right of way is available, the width of shoulders may be wider than 8 feet.
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