2011-05-24_PWETC_AgendaPacket - Laserfiche WebLink

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City of Des Plaines Neighborhood Traffic Management Policy PHYSICAL CHANGES TO STREETS Page 3 of 4 The main drawback of one -way street patterns is the frustration of having to navigate those one -way street patterns. In addition to simple frustration, the newly- introduced one -way pattern might force some residents to exit their neighborhood at an arterial intersection where turning movements are difficult rather than at the signalized intersection to which they formerly had access. Curb Extensions and Street Narrowings Curb extensions and other narrowings generally involve moving the curb toward the center of the street, thereby creating a bottleneck effect. Curb extensions can be applied at intersections to create a more narrow entrance to a block and to shorten the crossing distance for pedestrians. They can also be applied mid- block. This may require the removal of parking spaces. Curb extensions are most effective on wider streets with one or two parking lanes. The addition of the extensions tends to have a positive aesthetic benefit for the neighborhood due to the replacement of roadway with additional green grassy area. The cost of curb extensions varies dramatically depending upon the number of drainage structures that are impacted by the extension. Traffic Circles Traffic circles are raised circular islands constructed in the center of residential intersections. They reduce vehicle speeds by forcing motorists to maneuver around them. Drivers making left turns are directed to go on the far side of the circle prior to making the turn. The circles serve to break up long straight stretches of roadway and result in safer intersections. In addition, with landscaping the islands can improve the aesthetics of the neighborhood. Mid -block Islands Center Islands are used on long sections where there are no intersecting streets. This may require the removal of parking spaces in order to accommodate the shift in the travel lane. This measure serves to break up long, straight stretches of roadway that can encourage speeding. Speed Humps/Tables Speed humps are approximately 3 to 4 -inch high paved humps placed at strategic locations along a street to slow traffic. Humps typically extend the full width of the street with height tapering near the drain gutter to allow unimpeded bicycle travel. There are many different designs in circulation throughout the United States with the 12 -foot hump being the most prevalent. However, there has been a movement toward 14 -foot humps and even toward exclusive use of 22 -foot speed "tables" in some jurisdictions since they are easier on both standard vehicles and the more sensitive emergency response vehicles.