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<br />Vertical Elements <br /> <br />Speed Bumps/Humps/Tables <br /> <br />Purpose <br />A physical feature (usually made of <br />asphalt or rubber mounds) that are <br />designed to rise above the roadway <br />surface and extend across the roadway <br />perpendicular to the traffic flow. Typically <br />used to reduce vehicle speeds. <br /> <br />~W?DI <br />--~a--E <br />:::r, .. .... <br /> <br />~~ <br /> <br /> <br />_________ '.;: t:::>-_______ <br />(C!O ~., <br />-d :0; <br /> <br />Speed Table <br /> <br />u~~ <br /> <br />Speed Bump <br /> <br />Source: Institute of Transportation Engineers Traffic Calming: State of <br />Practice <br /> <br />Effects <br />Volumes May reduce traffic volumes <br />Speed Effective in slowing vehicles traveling at typical residential speeds to <br /> approximately 5 to 15 mph depending on type installed at the device - may <br /> reduce overall speeds by 5 to 7 mph. <br />Traffic Noise and Air May have an increase of noise at the bumps/humps <br />Traffic Safety Traffic safety has not been found to be compromised with these devices. Traffic <br /> safety benefits can be gained if speeding is involved. <br />Advantages . Reduces speeds <br /> . Usually reduces traffic volumes <br /> . Does not require parking removal or interfere with bicycle/pedestrian traffic <br />Disadvantages . Can potentially increase noise <br /> . Can cause traffic to shift to parallel residential or collector streets <br /> . May decrease emergency vehicles response times <br />Problems Targeted . Excessive speed <br /> . High volumes <br />Design . Speed humps are only effective for 250 feet on either side of the hump. Thus. a <br /> neighborhood considering speed hump installation would require two to three <br /> installations. <br /> <br />APRil 2005 <br /> <br />29 <br />