Northampton Main King Charrette v61511 17Main and King Streets Design Charrette Book
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Main and King Streets Design Charrette Book
Raised Crossing
Like speed tables, raised crossings are crossing
areas that are flat, raised areas with ramped
side. Raised crossing emphasize pedestrians
crossing the street by forcing vehicles to reduce
their speed in all conditions--whether or not
a pedestrian is present, emphasizing distinct
pedestrian space on the road. The crossing
should be level with sidewalks, eliminating the
needs for curb ramps.
Typically, raised crossings are flush with the
sidewalk, about 6” high, with grades not
exceeding 1:12. Raised crossings must be
accompanied with appropriate advanced driver
warning and reduced speed caution signage.
Careful design of approach and descent ramps
allows vehicle to maintain an urban minimum
speed limit (typically 25 to 30 mph).
Raised Table
A raised table or speed table is flat, raised area,
typically 3-4” high. They are ramped on each
side, as shown above. The raised area typically
covers the entire intersection as well as all
crossings, which eliminates the need for curb
ramps. Raised tables are typically installed on
two-lane roads with speed limits of no more
than 30 mph.
Approach and departure grades of 8% or less
should be designed with emergency appartus in
mind. In mid-block locations, tables generally
should be at least 22’ long.
Leading Pedestrian
Interval
A leading pedestrian interval (LPI) gives extra time
for pedestrians to cross at the beginning of a
light-cycle while parallel traffic still has a red-light,
improving the flow of the intersection for cyclists
and drivers alike. The LPI decreases the conflict
between pedestrians and oncoming left- and right-
turning vehicles that normally all share a green-
light/pedestrian signal for the same length of time,
allowing pedestrians as well as left- and right-
turning vehicles to clear the intersection faster by
processing pedestrians quickly at the start of the
signal phase. They also provide increased visibility
of pedestrians by drivers. The length of an LPI is
typically 3-5 seconds, depending on pedestrian
volumes and traffic calming treatments that narrow
the crossing.
Crossings
Source: Richard Drudl, Flickr Source: http://www.transalt.org/files/newsroom/
magazine/044Fall/16safeseniors.html
Sidewalk &
Curb Extensions
Wider Sidewalks
Wider sidewalks provide sufficient space for
people (including children) to interact and
socialize, not just walk, while allowing for enough
room to comfortably walk down the street. Wider
sidewalks also provide for 2 wheelchairs to pass
side-by-side as well as larger groups and families.
Space allowing, wider sidewalks can provide for
outdoor seating areas, planting beds, shade-
providing street trees, art installations, outdoor
dining space for local restaurants, and vending/
display space for other local businesses. Outdoor
dining and vending might require zoning changes.
The minimum width for sidewalks should begin at
5’-8’ and should be up to 15’ near schools, parks,
commercial areas, and other busy pedestrian
areas.
Crossing Islands
Crossing islands or pedestrian refuges enhance
pedestrian safety by allowing pedestrian to
cross one direction of traffic at a time while
simultaneously calming vehicle speeds. Crossing
islands reduce the distance that pedestrians must
cross at one time, allowing them to cross one
direction of traffic and wait safely in the median
area until traffic is clear on the other side of the
street.
Crossing islands have the advantage of not
requiring additional drainage infrastructure, as
opposed to a curb extension or other device that
decreases crossing ditance. The minimum island
width is 6’, which allows for bikes and strollers
to be protected from traffic. Width of the island
cut should be 5’ (no ramps needed), and cuts
wider than 8’ should include bollars to discourage
accidental vehicle use. Signage is necessary.
Curb Extensions
Curb extensions, or bulb-outs, are extensions of
the sidewalk, as shown above, that narrow the
street in order to decrease pedestrian crossing
distances and reduce vehicle speeds. Bulb-outs
also serve to expand the pedestrian realm as an
extension of the sidewalk.
Used at intersections and mid-block conditions,
they are typically employed where on-street
parking is present. The width of the curb
extension should be equal to at least that of the
parking lane, though the minimum of 5’ may be
used in snow climates. Length of the bulb-out
varies with the placement of drainage facilities
and is often 20’ or more to enforce corner
clearance of parked cars.
Source: Richard Masoner, Flickr Source: Dan Burden, pedbikeimages.orgSource: Dan Burden, pedbikeimages.org