Signing
and Pavement Markings-Additional
speed limit signs can be installed.
Pavement markings such as striping on-street parallel parking spaces can
be installed to reduce the travel width of the street. Both of these measures have a minimal effect
in reducing speeds.
Speed
Tables-A raised area of street
pavement, three to four inches in height.
Speed tables are different from speed bumps and humps. Speed bumps are abrupt and are generally use
in parking lots. Speed humps are more gradual and not as severe as speed bumps. Speed tables are even more gradual, usually
with a flat top and in the range of 22 feet in length across the entire
street. To be effective these measures
are typically placed in series rather than singularly with a spacing of
approximately 300-500 feet.
Raised Crosswalks-Flat raised pavement areas covering only the pedestrian crosswalk
areas. The crosswalk areas can use grooved asphalt,
colored paving stones or brick.
Raised
Intersections-Flat raised areas
covering entire intersections, with ramps on all approaches and often with
brick or other textured materials in the flat section. Raised pavement can use grooved asphalt,
colored paving stones, brick, or for ultimate effectiveness, cobblestones.
Textured
Pavements-Streets surfaces paved
with brick, concrete pavers, stamped asphalt, or other surface materials that
produce constant small changes in vertical alignment.
Traffic Circles-A raised circular island in the center of the intersection. Generally
used in residential areas and may be as small as 16 to 25 feet in
diameter. Forces motorists to slow or
alter their speed. This design requires
vehicles to keep right and travel through the intersection in a
counter-clockwise direction around the island.
Roundabouts-An
intersection design that uses a circular island rather than traffic signals or
stop signs. This type of design encourages lower speeds
as vehicles drive through the intersection.
Generally installed on higher volume streets.
Chicanes-Curb
extensions that alternate from one side of the street to the other, forming
S-shaped curves. They are also referred to as deviations,
serpentines, reversing curves, or twists.
Realigned Intersections-Changes in alignment that convert T-intersections
with straight approaches into curving streets that meet at right angles. A former
“straight-through” movement along the top of the T becomes a turning
movement. They are sometimes called
modified intersections.
Neckdowns-Curb extensions at intersections that
reduce street width curb to curb. They are sometimes called nubs, bulbouts, knuckles, or intersection narrowing.
Chockers-Curb extensions at midblock
that narrow a street by widening the sidewalk or planting strip. They are
sometimes called pinch points, midblock narrowing, or
constrictions. They can maintain two
lanes of traffic or reduce traffic down to one lane.
Full
Closures-Barriers place across a
street to close the street completely to through traffic, usually leaving only
sidewalk or bicycle paths open. The
barriers consist of landscaped islands, walls, gates, side-by-side bollards, or
any other obstructions that leave an opening smaller than the width of a
passenger car. Full closures are the
most commonly used cure for cut-through traffic.
Half
Closures-Barriers that block travel
in one direction for short distance on otherwise two-way streets. They are also sometimes called partial
closures or one-way closures. Half
closures are the most common volume control measure after full closures.
Diagonal
Diverters-Barriers placed diagonally
across an intersection, blocking through movement. They are also called full diverters or
diagonal road closures. Diagonal
diverters are usually staggered to create circuitous routes through
neighborhoods. There are also half diagonal diverters.
Forced Turn Islands-Raised islands that block certain movements on approaches to an
intersection. They are sometimes called forced turn channelizations, pork chops, or right turn islands.