– Concrete curbs are generally classified as barrier curbs or mountable curbs. Either type can be constructed in many different shapes, depending on regional preferences, purposes and construction costs.
– Barrier curbs, also known as straight curbs, resemble the stone slabs used originally for curbs and form abrupt obstacles to vehicles leaving pavements.
– Mountable curbs, sometimes referred to as roll curbs, have sloping faces that allow vehicles to encroach on them without damaging tires and wheels; and if the slopes are gentle enough, cars can cross them to access driveways.
Either type of curb can have an apron or gutter section attached and become a combined curb and gutter. Combined curb and gutter sections are commonly used along streets and parking lots in urban areas, especially with asphalt pavements, to provide the advantages of stable concrete gutters with sustainable flow lines along the curbs.
Because concrete can be readily shaped to transition between cross-sections, curbs can be tapered to meet ramps for pedestrian crossings where these are preferred or to meet requirements for the disabled.
A separate curb and gutter must be tied to the pavement slab with deformed steel bars if there is to be effective load transfer. If a curb is separate from the pavement the joint between the pavement and the curb may require maintenance.