kerbing

Kerbing, also spelled curbing in American English, refers to the construction and installation of a curb along the edge of a street, sidewalk, or drainage channel. Curbs define the boundary between pavement and pedestrian areas, help direct surface water into drainage systems, and provide structural support for the pavement edge. They also improve pedestrian safety by preventing encroachment by vehicles and by guiding wheel alignment near intersections.

Most kerbs are made of concrete, but stone, precast concrete, or asphalt have been used in some settings; metal or plastic kerbs are employed for temporary works or specialized applications. Common types include standard vertical curbs, mountable curbs (which allow some vehicle passage but reduce damage to tires), and barrier or slot curbs designed to deter or contain vehicles. Precast kerbs offer uniform profiles and faster installation, while cast-in-place curb forms are shaped in the final road grade. Radii and cross-sections are designed to suit drainage, sidewalk grade, and expected turning movements.

Design and construction consider alignment with the road profile, drainage requirements, and accessibility features such as curb ramps. The edge height, curvature, and joints influence durability and maintenance. In climate zones with freeze-thaw cycles, proper jointing, backfilling, and insulation are critical to prevent cracking and settlement.

Maintenance involves inspecting for cracking, spalling, settlement, or misalignment, and performing repairs or replacements as needed. Replacement may require matching the local kerb profile and height to ensure drainage and accessibility remain compliant. Standards vary by country and region; guidelines are provided by national and municipal road authorities, such as AASHTO in the United States and equivalent bodies elsewhere.

Kerbing has evolved with road engineering practices, with early curbs primarily serving drainage and edge protection and modern kerbs combining drainage, safety, and accessibility considerations. Designs reflect climate, traffic volumes, and urban form, resulting in substantial regional variation in profiles and materials.