Curb

**History of Curbs:**
– Curbs have been used since ancient times.
– In the 18th century, curbs became widespread for city beautification.
– Paving Acts in the 18th century authorized footways in London with curbs.
– Curbs became common in London streets with the introduction of macadam roads in the 19th century.
– The first curb cuts were installed in Kalamazoo in 1945.
– The Americans with Disabilities Act of 1990 improved accessibility for wheelchair users.

**Function and Purpose of Curbs:**
– Curbs delineate pavement edges and discourage parking on sidewalks.
– They provide structural support and channel runoff water into storm drains.
– Curbs add an aesthetic aspect to roads and inform pedestrians to stop or slow down before crossing.
– They are more common in urban areas due to cost and drainage conditions.
– Curbs are not universally used, especially in rural areas.

**Safety Considerations with Curbs:**
– Curbs channel traffic and provide redirective capacity in low-speed environments.
– On high-speed roads, curbs mainly serve drainage purposes.
– Vehicles hitting curbs can be tripped into rollover crashes or vaulted into the air.
– Curbs can lead a vehicle towards the sidewalk in high-speed collisions.
– Proper placement of curbs and traffic barriers is essential for safety.

**Types and Materials of Curbs:**
– Curbs vary by shape, material, height, and whether combined with a gutter.
– Different types include integral curb, curb and gutter, slope-faced curb, narrow dropped curb cuts, and high containment kerbs.
– Curbs are made of materials like asphalt, stone, masonry blocks, or concrete.
– Portland cement concrete is the most common material for curbs.
– Material choice depends on the road surface and desired function.

**Design and Features of Curbs:**
– Engineers specify the reveal or lip for curbed roadways.
– Typical reveals range from 4 to 8 inches.
– Curbs at handicapped curb cuts should have no reveal.
– Integral gutters provide better hydraulic flow performance.
– Curbs can be painted for increased visibility or special markings.
– Auto racing curbs are essential for maintaining safety on tracks.
– Curb design can signify cultural associations in different regions.