Curbs and Gutters
Advantages of Curbs
Advantages | Types | Requirements | Design | AASHTO Standards | Joints | Drainage | Materials | Construction
Curbs provide several advantages:
The neat, straight lines of curbs add to the attractiveness of parking lots and streets, and the commonly used expression "curb appeal" implies that attractiveness of adjacent properties are also enhanced by sharp demarcations between streets and lawns.
Curbs strengthen pavements. The confining of flexible pavements by concrete curbs improves compaction during construction and helps maintain the integrity of edges under traffic. The added thickness given to edges of concrete pavements by integral curbs increase strength and stiffness, reduce deflections induced by traffic loads, and therefore extends pavement life.
Curbs reduce the amount of space or right-of-way required for a street by eliminating drainage swales and their flat side slopes; curbs also reduce the lengths of driveways built from streets to homes or businesses. In some jurisdictions where both curbed and uncurbed streets are allowed by subdivision ordinances, streets with curbed sections require less dedicated right-of-way than streets without curbs, for example 50 ft for local streets with curbs, or 60 ft for local streets without curbs. The elimination of drainage swales also reduces maintenance by eliminating the cleaning of ditches, the mowing of ditch banks, and the care of culverts and their end sections that carry water under driveways.
Light reflective surfaces of concrete curbs delineate pavement edges and improve visibility for drivers at night, thus promoting safety. Where there are no concrete curbs to outline the edges of roads and streets, it is now common practice to mark the pavement edges with stripes of white paint.
Curbs improve the efficiency of street sweepers by concentrating debris for easy, mechanical pickup, as opposed to having it scattered along shoulders and drainage swales where it must be picked up by hand.
Concrete curbs have the integrity to withstand the impacts of snowplows.
A comparison of pavement sections with curbs and without curbs is shown in this figure, illustrating the advantages in land use provided by concrete curbs. It should be noted that most of the advantages listed above pertain only to concrete curbs or concrete curbs and gutters that extend down to the bottom of pavements. Adding asphalt curbs along the edges of asphalt pavements cannot provide the confinement to improve compaction or other long-term benefits.