Neckdowns are:
- Horizontal speed control measures.
- Curb extensions at intersections that reduce the roadway width and
tighten the curb radii at the corner. This provides a shorter distance
for pedestrians to cross and reduces the speed of turning vehicles.
- Also referred to as bulbouts, intersection narrowings, and nubs.
- Usually constructed as an extension of the curb, sidewalk, and planting
strip.
- Usually installed in pares, one on each side of the road.
- Able to be integrated with crosswalks to provide a safer pedestrian
crossing by reducing the crossing distance, improving the line-of-site
for pedestrians, and making pedestrians more visible to drivers.
- Ideal for heavy pedestrian areas, residential areas, commercial
areas, and business districts.
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Typical Design:
- The extension into the roadway is variable depending on the existing
width.
- Neckdowns are usually constructed as an extension of the curb, sidewalk,
and planting strip.
- Curbs on the extensions can be vertical or mountable if it is necessary
to accommodate larger turning vehicles.
- The Institute of Transportation Engineers has design recommendations.(2)
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Placement Issues:
- Neckdowns are used at intersections.
- Neckdowns can be designed to protect parked vehicles.
- Crosswalks should be integrated with neckdowns to provide a safer
pedestrian crossing by reducing the crossing distance, improving the
line-of-site for pedestrians, and making pedestrians more visible to
drivers.
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Approximate Cost:
- Installation costs of neckdowns start around $4,000 and quickly go
up depending on the size, placement, curb work, and drainage work.
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Comments:
- Neckdowns can be integrated with other traffic calming measures like
speed humps, speed tables, raised cross walks, and medians.
- When designing a neckdown, considerable attention should be given
to aesthetics.
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Advantages
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Disadvantages
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- Provides a safer pedestrian environment.
- Can improve the aesthetics of a neighborhood when landscaped
tastefully.
- Very few problems reported
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