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SPEED
CUSHIONS
Note: These can also be used
in conjunction with bulges as shown in this schematic.
A speed cushion
is a variation on a standard speed hump. However, these devices
do not span the entire width of the roadway but taper off at the
edges. The width of the raised portion is sufficient to ensure
that cars have to pass over some of the hump but may allow buses
and emergency vehicles to pass over with less impact.
The speed cushion dimensions are about 7' wide, 10' long and 3"
tall. Most passenger vehicle axle widths are around 6', so they
cannot straddle speed cushions as emergency vehicles do.
Speed cushions are designed to slow traffic to 25 mph and lower
traffic volume by 5 - 7%.
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|
Permanent
Installation
Note: Buses are impacted less than cars
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PROS
1.
Potential to reduce traffic speed.
2. Reduces traffic volumes.
3. Can be used to reduce cut-through traffic.
4. Self-enforcing.
5. Minimal impact to on-street parking.
6. Minimum maintenance.
7. OK for emergency vehicles.
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CONS
1.
Care needed if placed on transit routes.
2. May transfer problems elsewhere.
3. Not aesthetically pleasing.
4. May cause vehicles to encroach into bicycle lanes.
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Summary
of Effectiveness
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Volume
Reduction
|
Yes
(Locally)
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Speed
Reduction
|
Yes
|
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Safety
Improvement
|
Possible
|
|
-
|
-
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Streets
to Use On – Collector, Local
|
Local
|
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Use
on Bus Route
|
Yes
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Use
with Curbs and Gutters
|
Yes
|
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Spot
or Area-wide Use
|
Spot
|
|
-
|
-
|
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Emergency
Service Access Issues
|
Minimal
|
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Impacts
on Arterials
|
Possible
|
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Change
in % Trucks
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Unknown
|
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Environmental
Changes
|
Unknown
|
|
-
|
-
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Dependence
on Enforcement
|
No
|
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Level
of Violation
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N/A
|
|
-
|
-
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Aesthetics
and Landscaping
|
No
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