Roadways: Paved Shoulders

Paved Shoulders

Primary Guidance Consider shoulder paving width The MDOT’s SHA Office of Materials Technology (OMT) will approve the pavement thickness for all projects on State highways Shoulder pavement depth design will be based on 10 percent of the mainline Average Daily Truck Traffic (ADTT) . Exceptions are: Shoulder pavement type can match the mainline surface if it is the most cost effective solution When drainage issues are or are likely to be present (Consideration should be given to match the mainline roadway overall pavement thickness [asphalt/concrete + aggregate base] by increasing the aggregate thickness to match the bottom of the roadway aggregate) Any auxiliary, acceleration, deceleration, and ramp lanes directly adjacent to mainline pavement shall be considered to be part of the mainline pavement until those lanes split off at the gore area Permeable pavements may be considered where significant right-of-way or other stormwater management (SWM) costs exist Permeable pavements shall not be used where the speed limit will be greater than 35mph

Discussion Paved shoulders and aggregate stabilized shoulders provide a secure surface to accommodate vehicles for emergencies and other uses. Paved shoulders are an integral part of the pavement structure and considered part of the pavement design configuration. The lead design office will decide the overall width of the paved shoulder. For maintenance, structural, or safety concerns, a 2 ft. minimum paved shoulder should be provided directly adjacent to traveled way. Shoulder pavement will not be designed to be the same thickness as mainline roadway. Except for the following exceptions, shoulder pavement design will be based on 10 percent of the mainline Average Daily Truck Traffic (ADTT) : Bridge Approaches, within 500 ft. of bridge Intersections, within 500 ft. of intersection Shoulders less than 6 ft. wide There is a significant likelihood that shoulders will be used for Maintenance of Traffic (MOT) at bridge approaches and converted to turn lanes at intersections. When less than 6 ft. wide, it is impractical to construct shoulders in a separate pass from the mainline. Where an additional lane is considered imminent, the shoulder should be designed for 100 percent traffic, with the width desired for future lane use. Ramp shoulders should be consistent with the mainline. Permeable pavements should only be considered in areas where the underlying subgrade drainage is good (typically sandy material), and provisions for routine maintenance must be made.

See Also

• Shoulder Width
• Practical Design Implementation Guidance