Curb Extension

Usage: Wide

An expansion of the curb line into the lane of the roadway adjacent to the curb (typically a parking lane) for a portion of a block either at a corner or mid-block. Also known as neckdowns, curb extensions can enhance pedestrian safety by reducing crossing distances, can relieve sidewalk crowding, and can provide space for functional elements such as seating, plantings, bike share stations, and furniture. In addition, two curb extensions can be located on either side of a street to create a Mid-Block Narrowing or at an intersection to create a Gateway.

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Metropolitan Avenue, Brooklyn
Bay Street, Staten Island

Benefits

  • Calms traffic by narrowing the roadway
  • Makes the crosswalk more apparent to drivers, encouraging them to stop in advance of the crosswalk, and reduces illegal parking within crosswalk
  • At a corner, slows turning vehicles and emphasizes the right-of-way of pedestrians
  • Shortens crossing distance, reducing pedestrian exposure
  • Enhances visibility of pedestrians to drivers
  • Reinforces lane discipline through intersection, preventing vehicle passing maneuvers in parking lane
  • Provides additional pedestrian space and reduces crowding, particularly for queuing at crossings and bus stops or at a subway entrance
  • Reduces sidewalk clutter by creating space for street furniture, bus stops, street vendors, etc.
  • Defines the ends of angle parking
  • Discourages truck turns onto streets with No Truck regulations and discourages or prevents vehicles from taking banned turns (see Rules of the City of New York, Title 34, Chapter 4, Section 4-13)

Considerations

  • May impact street drainage or require catch basin relocation
  • May impact underground utilities
  • May require loss of curbside parking
  • May complicate delivery access and garbage removal
  • May impact snow plows and street sweepers
  • May impact ability to install future curbside bike or bus facilities
  • Permits, revocable consents, and/or maintenance agreements may be required for certain furniture elements

Application

  • Within a curbside parking lane
  • Corners with marked pedestrian crosswalks in retail districts, directly adjacent to schools, at intersections with demonstrated pedestrian safety issues, on wide streets, or in areas of high foot traffic
  • At mid-block crossings (see Mid-Block Narrowing)
  • Intersections where a two-way road transitions to oncoming one-way operation so as to block wrong-way traffic from proceeding straight onto the one-way portion (a “blockbuster”)
  • Next to subway entrances or other sidewalk pinch points so as to increase pedestrian walking or queuing space
  • Near fire hydrants, to keep clear of parked vehicles
  • Consider elongated curb extensions for some or most of a block (i.e., a widened sidewalk with lay-by areas) in areas where a full sidewalk widening would be desirable but some loading, drop-off, or parking access must be maintained
  • Cannot be used where curbside travel (including bus, bike, or general traffic) lane exists, such as those created through peak-period parking restrictions
  • Feasibility is evaluated based on engineer review of design-vehicle turning movements

Design

  • Curb extension width is typically two feet less than the width of the parking lane. Minimum curb extension length is typically equal to the full width of the crosswalk, however it can be longer when appropriate or necessary
  • Must accommodate design vehicle; when a curb extension conflicts with design vehicle turning movements, the curb extension should be reduced in size rather than eliminated wherever possible
  • At crossings that have low pedestrian visibility, curb extension should be long enough to “daylight” the crossing, i.e., provide open sight-lines to the pedestrian crossing for approaching motorists; the additional curb extension space can be used to provide plantings (see Curb Extension in the Landscape chapter) or community facilities such as bike parking
  • Detectable warning strips are required at pedestrian crossings where the transition from pedestrian space to roadway is flush, and should be red when adjoining light-colored sidewalks, such as Unpigmented Concrete, or bright white when adjoining dark-colored surfaces, such as Pigmented Concrete, Asphalt Pavers, or Bluestone
  • Edge objects, such as planters, granite blocks, and flexible delineators, should be placed in and around the painted curb extensions to create a consistent boundary and sense of enclosure, buffer it from motor vehicle traffic, and clearly indicate the crosswalk to pedestrians with vision disabilities. Paint is used to distinguish it visually from the adjacent roadway
  • The design and placement of street furniture, trees, and plantings on a curb extension must not impede pedestrian flow, obstruct clear path, or interfere with “daylighting” the intersection, emergency operations, or sight lines
  • When constructed in concrete, Pedestrian Ramps with detectable warning surfaces are required at pedestrian crossings
  • Reflective vertical elements should be used to alert drivers and snow plow operators to the presence of curb extensions in operational materials
  • Curb extension must be designed so as to maintain drainage of stormwater from the gutter and not cause ponding; depending on site-specific grading conditions, this might include properly locating or relocating catch basins or utilizing design treatments that channel water through, around, or in between curb extension and the curbline
  • When a curb extension is used adjacent to a fire hydrant, the length of the curb extension should be equal to or greater than the No Parking zone (typically 15 feet in either direction) and the hydrant should be moved onto the curb extension
  • Where space permits, more functional curb extension designs, such as those with plantings, seating, or bike parking, should be used whenever possible. See Sidewalk Plantings in the Landscape chapter
  • Where feasible and if there is a maintenance partner, design planted areas within curb extension so as to capture stormwater according to current standards. See Stormwater Management Practices in the Landscape chapter
  • Paving on a curb extension should match that of the surrounding sidewalks
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