RESIDENTIAL Ribbon Sidewalk

Ribbon sidewalks are common in most residential areas. Design the pedestrian through zone to be roughly equal to the planted area, using pervious strips where applicable to help manage stormwater.

If a sidewalk is directly adjacent to the roadway, 2 feet should be added to

STREET TREES

the absolute minimum clear path

Street trees enhance city streets both

width to ensure that there is sufﬁcient

functionally and aesthetically. Trees

space for roadside hardware and snow

provide shade to homes, businesses,

storage. 8 Parking provides a valuable

and pedestrians. Street trees also have

buffer between the pedestrian and

the potential to slow trafﬁc speeds,

vehicle realm. Urban arterials or high- especially when placed on a curb

extension in line with on-street parking,

volume downtown streets directly

and may increase pavement life by

abutting the pedestrian realm should

avoiding extreme heat. Aesthetically,

property lines, setback from curb,

and integration with street lights and through a street furniture zone, parking,

be buffered in some capacity, whether

street trees frame the street and the

sidewalk as discrete public realms,

other furniture.

enriching each with a sense of rhythm

Street trees may be removed to satisfy of minimum dimensions directly

cycle track, or other feature. Sidewalks

and human scale.

sight distance or clear zone require- adjacent to the traveled way should

Requirements for tree spacing depend

ments only in extreme cases, where the

upon a number of key factors and

installation of trafﬁc control devices has

be avoided.

should be tailored to the chosen species,

been precluded. Larger trees protect

standard (or desired) tree pit size, ﬁxed

pedestrians from errant vehicles.

S T R E E T D E SI G N E L E M E N T S

When pedestrian networks cross municipal boundaries, efforts should

be made to ensure seamless continuity

CLEAR ZONES

of the pedestrian infrastructure.

The concept of “clear zones” is sometimes cited in the highway

OPTIONAL

design process. A clear zone repre- sents an unobstructed, traversable

In newer residential areas, many

area beyond the traveled way, often

streets have been constructed

a paved or planted shoulder or a

short setback on the sidewalk. without sidewalks. If trafﬁc volumes 9 are sufﬁciently low in these areas,

Clear zones provide a run-off zone

consider designating or upgrading

for errant vehicles that have deviated

these areas to shared streets. This

from the main roadway and are

requires the addition of speciﬁc trafﬁc

Clear zones are applicable on rural calming devices and regulations that

intended to decrease the frequency

highways with high vehicle speeds, offset potential conﬂicts with trafﬁc 10 crashes, forgiving driver error.

and severity of ﬁxed-object roadside

not in urban areas. accessing local properties.

While clear zones are applicable

Removal of roadside impediments

(trees, street furniture, etc.) has an Many older residential areas have trees

as a safety parameter for the

ambiguous safety record in urban whose roots have compromised the

Interstate and freeway system, in

environments and is at odds with integrity of the sidewalk. On

urban settings, clear zones are not

city policies striving to increase low-volume roads, consider the

applicable or feasible due to right-

pedestrian trafﬁc and spur economic application of a curb extension that

of-way limitations and potential

safety hazards. To the greatest activity. Street trees and other obviates the need to remove trees or

roadside features are superior to the installation of a wider sidewalk

extent possible, the lateral distance

wide shoulders or run-off zones, as during reconstruction.

between the traveled way and the

sidewalk (or parking lane) should be

they can decrease overall speeds

and encourage a more pedestrian- Where pedestrian volumes create

minimized, providing ample space

for sidewalks and other amenities. 11 friendly environment. congested conditions along sidewalks,

cities are encouraged to pursue temporary means to ease overflow from the sidewalk onto the streets. Interim elements, such as epoxied gravel pavements or temporary lane closures, may be able to provide an interim solution until a city can widen the walkway. If special events are anticipated to significantly increase pedestrian traffic, similar strategies should be pursued to ensure pedestrians are not forced into vehicular traffic.

Lane closures should be considered to ease sidewalk congestion during times with known high pedestrian volumes.

Curb Curb extensions visually and physically narrow the roadway,

creating safer and shorter crossings for pedestrians while

Extensions

increasing the available space for street furniture, benches, plantings, and street trees. They may be implemented on downtown, neighborhood, and residential streets, large and small. Curb extensions have multiple applications and may

be segmented into various sub-categories, ranging from trafﬁc calming to bus bulbs and midblock crossings.

S T R E E T D E SI G N E L E M E N T S

Used as a bus bulb, curb extensions

APPLICATION

BENEFITS & CONSIDERATIONS

may improve bus travel times by reducing the amount of time a bus

Curb extension is an umbrella term

takes to merge with trafﬁc after that encompasses several different

Curb extensions decrease the overall

boarding. Bus bulbs also help to treatments and applications. These

width of the roadway and can serve

prevent motorists from double include:

as a visual cue to drivers that they

are entering a neighborhood street

parking in the bus stop. 3

or area.

• Midblock curb extensions, known as pinchpoints or chokers, which may

Where application of a curb extension

include cut-throughs for bicyclists. adversely impacts drainage, curb

Curb extensions increase the overall

extensions may be designed as edge • Curb extensions used as gateways to

visibility of pedestrians by aligning

islands with a 1–2-foot gap from the minor streets known as neckdowns.

them with the parking lane and

reducing the crossing distance for

curb or a trench drain.

pedestrians, creating more time for

• Offset curb extensions that force

vehicles to move laterally, known Curb extensions can be implemented

preferential treatments, such as

as chicanes. using low-cost, interim materials. In signal priority. 1 such cases, curb extensions should be

leading pedestrian interval and transit

• Curb extensions at bus (or transit) demarcated from the existing road- stops, also known as bus bulbs.

Curb extensions tighten intersection

bed using temporary curbs, bollards,

planters, or striping. • Conventional curb extensions, which

curb radii and encourage slower

turning speeds.

are a recommended feature where there is on-street parking.

Installation of curb extensions may require moving a ﬁre hydrant to

maintain adequate curbside access in case of a ﬁre. In such cases, a curb extension may incur additional expense or be reoriented to avoid conﬂict with the hydrant. 2

GAT E WAY

Gateway

Curb extensions are often applied at the mouth of an intersection. When installed at the entrance to

a residential or low-speed street,

a curb extension is referred to as a “gateway” treatment and is intended to mark the transition to

a slower speed street.

CRITICAL

Curb extensions should be installed

OPTIONAL

whenever on-street parking is

The length of a curb extension should

Curb extensions may be treated with at least be equal to the width of the

present to increase visibility, reduce

corner street furniture and other ame- crosswalk, but is recommended to

the crossing distance, provide

nities that enhance the public realm. extend to the advanced stop bar.

extra queuing space, and allow for

enhancements, such as seating or greenery.

RECOMMENDED

2 Combine stormwater management features, such

1 A curb extension should generally

as bioswales or rain gardens, with

be 1–2 feet narrower than the

curb extensions to absorb rainwater

parking lane, except where the parking

and reduce the impervious surface

lane is treated with materials that

area of a street.

integrate it into the structure of the sidewalk.

NEW YORK, NY

In advance of a full reconstruction, gateways can be designed using striping or signage that communicates the entrance into a slow zone.

NEW YORK, NY

INDIANAPOLIS, IN

Curb extensions may be combined with bioswales in order to decrease puddling at crosswalks.

S T R E E T D E SI G N E L E M E N T S

Pinchpoint

Curb extensions may be applied at midblock to slow trafﬁc speeds and add public space. When utilized as a trafﬁc calming treatment, mid-

1 block curb extensions are referred to as "pinchpoints" or "chokers".

RESIDENTIAL Ribbon Sidewalk