Curb extension

A curb extension (or also neckdown, kerb extension, bulb-out, bump-out, kerb build-out, nib, elephant ear, curb bulge,"curb bulb" and blister) is a traffic calming measure, primarily used to extend the sidewalk, reducing the crossing distance and allowing pedestrians about to cross and approaching vehicle drivers to see each other when vehicles parked in a parking lane would otherwise block visibility.

A curb extension is an angled narrowing of the roadway and a widening of the sidewalk (pavement or footway in UK usage). This is often accompanied by an area of enhanced restrictions (such as a "no stopping" or "no parking" zone) and the appropriate visual reinforcement. This is achieved using painted road markings (e.g. lines, coloured areas, or chevrons), barriers, bollards, or the addition of pavement or street furniture (e.g. planters, lamp standards, or benches).

Curb extensions are often used in combination with other traffic calming measures such as chicanes, speed bumps, or rumble strips, and are frequently sited to "guard" pedestrian crossings. In these cases the "squeeze" effect of the narrowed roadway shortens the exposed distance pedestrians must walk.

The primary use of curb extensions are to improve visibility of pedestrians and reduce their exposure to motor vehicles.

Curb extensions are also in a number of special circumstances:

Curb extensions are also used when retrofitting existing streets to accommodate congestion charging schemes - hitherto wide (sometimes multi-lane) roads are deliberately narrowed to ensure that the charging equipment can see passing vehicles, and the charging equipment (and often bollards or other barrier devices) are placed in the expanded sidewalk area (to prevent drivers from circumventing the charging system's cameras and detectors).

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Wikipedia