NYC DOT - Pedestrians - Traffic Calming Design Guidelines

The term "traffic calming" is applied to design interventions that make streets safer by reducing opportunities for illegal speeding and aggressive driving. These measures can also enhance pedestrian comfort and flow. Measures may include the installation of traffic calming devices such as speed bumps, curb extensions, raised crosswalks, as well as other interventions. The Street Design Manual is a comprehensive resource for in-depth information on NYC DOT's traffic calming toolkit.

Traffic calming devices are part of a toolbox of measures NYC DOT uses to enhance safety, along with engineering and signal timing changes, and education and enforcement initiatives. Community groups, elected officials and Community Boards can report conditions (e.g. speeding) to the appropriate NYC DOT Borough Commissioner for analysis and consideration for traffic calming interventions or other safety measures.

NYC DOT has taken unprecedented steps to focus its safety engineering efforts in areas around schools and seniors, including the use of traffic calming devices. NYC DOT's safety programs include:

Safe Streets for Seniors

This program is a major pedestrian safety initiative for older New Yorkers. NYC DOT evaluates pedestrian conditions from a senior's perspective to implement safety engineering changes in 25 neighborhoods citywide that have both a high density of senior residents and a high number of senior pedestrian fatalities and severe injuries.
Learn more about Safe Streets for Seniors

Traffic Calming Devices

Below is a list of traffic calming devices used by NYC DOT, which includes the benefits, considerations, appropriate conditions for installation and design guidelines for each device. The guidelines below are not a replacement for thorough investigation and engineering.

Raised Speed Reducers

Lane Narrowing and Lane Removal

Curb Extensions

Traffic Diverters

Median Barriers

Raised Crossings

Raised Speed Reducers

A raised speed reducer is a raised area of a roadway that deflects both the wheels and frame of a traversing vehicle with the purpose of reducing vehicle speeds. This treatment is widely used.

The two basic types of raised speed reducers are speed humps and speed cushions. Speed humps are continuous raised areas that span the entire roadway, while speed cushions are rounded or flat topped raised areas placed across the road with wheel cutouts designed to allow large vehicles, such as fire trucks and buses, to pass with minimal slowing or rocking. Both are typically raised 4 inches above the level of the roadway, and both have a proven speed-reducing track record in New York City.

Benefits

Compels drivers to travel at speeds no higher than the street's design speed

A speed reducer can be used to provide a raised mid-block crossing in conjunction with a stop control

Considerations

Snow plows must be given advance warning

May generate additional noise

Appropriate Conditions for Installation

Can be requested by a Community Board or other community group, elected officials or individual citizens, with approval based on a NYC DOT field study of the location using speed survey, geometric, and street operations criteria. Requests can be made by emailing the Commissioner or writing a letter to the Commissioner, Department of Transportation, 55 Water Street, New York, NY 10041.

A field review is conducted to determine feasibility of a raised speed reducer based on the following criteria:

Street shall be at least 1,000 feet clear of a speed camera located in the same segment

On all other streets, including school blocks, the 85th percentile speed shall be equal to or greater than 30 mph

Street shall not have a Fire Department house or hospital emergency entrance located on the block. Moreover, any segment that allows for a movement away from the firehouse block, will only be considered for speed cushions and not humps. Crash criteria will still apply when pre-screening for speed cushions

Can be either one-way or two-way but should have only one moving lane in each direction

If street width is greater than 45 feet, then lanes should be clearly marked to establish that there is unambiguously one moving lane in each permitted direction

No speed reducer shall be installed at a critical point in a roadway system (e.g., at a severe horizontal, or vertical curvature) or on streets with more than an 8% grade

Segments that are bus and/or truck routes, cannot receive speed humps but only speed cushions

Segments being reviewed for speed cushions must be 5 KSI (Killed or Severely Injured) per mile or above (all modes) for the most up to date 5-year period. This includes school blocks

Segments being reviewed for speed cushions shall not exceed a bus volume of 12 buses per hour

Two-way segments with parking on both sides that are being reviewed for speed cushions cannot be less than 35 feet wide

Placement of a raised speed reducer shall be at least:

5 feet from any driveway or curb cut on a local street (additional clearance may be required for curb cuts utilized by trucks)

15 feet clearance from either side of a hydrant

On entrance to a block with a speed reducer:

70 feet between the intersection and the speed reducer

On exit from a block with a speed reducer:

70 feet between the speed reducer and an uncontrolled intersection (only on one-way streets)

150 feet between the speed reducer and a stop controlled intersection for two-way streets and 70 feet for one-way streets

150 feet between the speed reducer and a signalized intersection

200 feet from a curve in the roadway

250 feet minimum spacing between reducers

2 feet from a manhole or utility cover on approach or 5 feet after the reducer

The location can be investigated by NYC DOT for a "School Slow Zone" if a speed reducer is not feasible and is immediately adjacent to a school.

Design Guidelines

Speed reducers are built 4 inches high (on local streets without a school as well as near school locations)

Space raised speed reducers to maintain desired operating speeds

Appropriate warning signs and roadway markings should accompany raised speed reducers

Locate raised speed reducers in the middle of the roadway, with the gutters kept clear for proper road drainage

Use signage or other methods to alert operators of snow-clearing vehicles to the presence of raised speed reducers

While raised speed reducers are an effective method to retrofit existing streets to reduce motor vehicle speeds in lieu of street reconstruction, all newly reconstructed streets should be comprehensively designed to achieve desired speeds, e.g., using appropriate roadway width and alignment, horizontal deflection, traffic controls, trees, and other traffic calming treatments

Lane Narrowing and Lane Removal

A lane narrowing removes excess width from existing moving/traffic lanes without changing the number of lanes. A lane removal reassigns underused traffic lanes to other functions. This treatment is widely used.

These design techniques, while not traffic calming devices, have powerful traffic calming benefits. Both may be accomplished by adding turning lanes, pedestrian refuge islands, expanded pedestrian space, on-street or separated bicycle lanes, parking or other functions.

Benefits

Reduce opportunities for speeding and aggressive driving, reducing the severity and frequency of crashes

Organize the roadway to provide clearer instruction to drivers, cyclists, and pedestrians

Provide space for pedestrian refuge islands, assigned turn lanes, angle parking, wide parking lanes, bus lanes, bicycle lanes, expanded sidewalks/pedestrian space, or other uses

Considerations

Traffic conditions must be considered in planning lane removals; detailed analysis may be needed

Commercial loading and other uses should be considered in planning lane narrowing

Planned uses, such as bus lanes or bicycle lanes, should be taken into consideration

Effects of narrowings on turning movements should be tested

Appropriate Conditions for Installation

Consider lane narrowings on corridors with excessively wide lanes

Multi-lane corridors with excess capacity (more traffic capacity than traffic volume) are excellent candidates for lane removal

Multi-lane corridors may be good candidates for lane removal in concert with other treatments, such as signal timing changes

Lane narrowing and removal should be prioritized on corridors with safety or speeding concerns, or where prioritization of non-general traffic is desirable

Design Guidelines

Lane narrowings and removals should result in standard-width lanes

When other treatments are included in a lane narrowing/removal, see specific guidelines for those treatments

Curb Extensions

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. This treatment is widely used.

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, 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.

Benefits

Calms traffic by physically and visually narrowing the roadway

At a corner, slows turning vehicles and emphasizes the right of way of crossing pedestrians

Shortens crossing distance, reducing pedestrian exposure and minimum required signal time for crossing

Improves the ability of crossing pedestrians and drivers to see each other

Makes the crosswalk more apparent to drivers, encouraging them to stop in advance of the crosswalk and reducing illegal parking within crosswalk

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 when located at a subway entrance or other protrusion

Creates space that may be used to locate street furniture, bike parking, bus stop, public seating, street vendors, etc., potentially reducing sidewalk clutter

Keeps fire hydrant zone clear when located in front of a hydrant

Defines the ends of angle parking

Can discourage truck turns onto streets with no truck regulations

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

Appropriate Conditions for Installation

Only applicable 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 school crosswalks

At mid-block crossings

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

In front of fire hydrants so as to keep clear of parked vehicles

Consider at all corners and pedestrian crossings

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, bicycle, or general traffic) lane exists, such as those created through peak-period parking restrictions

Feasibility of curb extensions is evaluated based on engineer review of design vehicle turning movements and vehicle turning volumes

Design Guidelines

Curb extension width is typically two feet less than the width of the parking lane, but the curb extension can also extend to the bicycle lane when one is striped. Minimum curb extension length is typically equal to the full width of the crosswalk, however it can be longer when appropriate or necessary

A fire truck turning zone with a 50-foot outside radius should be maintained clear of physical obstructions (signs, planters, non-flexible bollards, trees)

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 may 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 or community facilities such as bicycle parking as long as visibility is not hindered

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

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 catch basins or utilizing design treatments that channel water through, around, or in between curb extension and the curbline

When space permits, more functional curb extension designs, such as those with green street/planted areas or community facilities such as seating or bicycle parking should be used whenever possible

Vertical elements should be used to alert drivers and snow plow operators to presence of the curb extension

To reduce the cost and implementation time of curb extension, trench drains can be considered instead of catch-basin relocation if a maintenance partner exists to clean the trench drain

When curb extension is used at 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.

Paving on curb extension should match that of the surrounding sidewalks.

Traffic Diverters

Traffic diverters are a family of traffic calming treatments that can be used to slow, redirect or block motor vehicle traffic, primarily at intersections. This treatment is used on a limited basis.

In areas where a goal is to reduce motor vehicle through-traffic, it may be desirable to create physical barriers that make it impractical or impossible to use local streets for anything other than local access trips.

Benefits

Reduces or eliminates short-cut and cut-through traffic

When applied consistently to an area, reduces traffic speeds

Can green and beautify the streetscape with trees and/or vegetation, improving environmental quality and potentially incorporating stormwater source controls

Considerations

May require further changes to traffic network operation; consideration must be given to local traffic network connectivity, and a traffic diversion analysis should be performed

May impact street drainage or require catch basin relocation

May impact underground utilities

Emergency vehicle access needs must be accommodated

Landscaping or stormwater source controls require a partner for ongoing maintenance

If outfitted to capture stormwater, careful consideration must be given to design, overflow control, and plant species

Appropriate Conditions for Installation

Consider on local streets with speeding or cut-through/short-cutting issues

Design Guidelines

Design traffic diversion devices to impact motor vehicle movement but not bicycle movement; utilize bike channels or similar design strategies to allow passage by bicyclists

Include planted areas and stormwater source controls within traffic diverters wherever possible when a maintenance partner is identified

If work includes tree planting, consider the location of utility infrastructure, including NYC DEP sewers and water mains

Median Barriers

A median barrier is a type of traffic barrier, which is usually an elevated median or median safety island extended through an intersection to prevent left turns and through-movements to and from the intersecting street. This treatment is used on a limited basis.

Pedestrian access can be maintained with pedestrian refuges and bicycle access with gaps in the median. As with typical medians, trees or plantings can be included within the median barrier.

Benefits

See Benefits for traffic diverters

Enhances safety at intersection by reducing potential vehicle movements and conflicts, particularly left turns

Reduces risk of vehicle head-on collisions

Reduces risk of motorists running a red light or stop sign when approaching from side street

Calms traffic on side street by requiring turn and on major street by narrowing roadway

Enhances pedestrian safety and accessibility by reducing crossing distances and providing refuge for pedestrians to cross the road in stages

Appropriate Conditions for Installation

See Appropriate Conditions for Installation for traffic diverters

One-way or two-way local streets at their intersections with two-way collector or arterial roadways

Design Guidelines

See Design Guidelines for traffic diverters

Raised Crossings

A raised crossing (e.g. raised walkway) is a marked pedestrian crosswalk at an intersection or a mid-block location constructed at a higher elevation than the adjacent roadway. This treatment is used on a limited basis.

A raised crossing is essentially a speed table, with the full width of the crosswalk contained within the flat portion of the table, usually 10 to 15 feet wide. It combines the benefits of a raised speed reducer with enhanced visibility for the pedestrian crossing.

Benefits

Compels drivers to travel at speeds no higher than the street's design speed

Improves drivers' awareness of presence of pedestrian crossing, particularly at mid-block crossing locations

Used at street gateways, can alert drivers that they are entering a slower-speed, pedestrian-oriented street environment

Allows convenient pedestrian circulation between high foot traffic destinations on opposite sides of a street

Considerations

May impact street drainage or require catch basin relocation

Appropriate Conditions for Installation

Existing stop-controlled crosswalks or other locations where demand exists for a stop-controlled pedestrian crossing that also meet the criteria for raised speed reducers

Consider at areas of particularly high pedestrian crossing demand on narrower streets (maximum of two moving lanes), such as locations with pedestrian generators (e.g., major commercial or cultural destinations, transit entrances, parks) on opposite sides of the street

Consider as a more robust option for mid-block crossings

Consider on the outer roadways of multi-lane boulevards at crossings

Avoid on arterial roadways

Design Guidelines

Appropriate warning signs and roadway markings should accompany raised crossing

Use signage or other methods to alert snow-clearing vehicle operators to the presence of raised crossing

Use enhanced, high-visibility street materials to further draw attention to raised crossing