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City of Des Plaines Neighborhood Traffic Management Policy Page 2 of 4 stop signs and the level of speed limits are subject to the federal Manual of Uniform Traffic Control Devices (MUTCD). For example, the role of stop signs is to control right -of -way. They are explicitly not to be used in controlling speeding. The reason for this is that decades of national and local research have revealed that using stop signs where they are not warranted for controlling right of-way actually makes conditions less safe for pedestrians due to more drivers ignoring these unwarranted signs and also by reducing the credibility of warranted stop signs. Similarly, artificially reduced speed limits have been unquestionably shown to not reduce speeds. They serve only to make violators out of even responsible drivers. While it is quite easy and inexpensive to litter the City with stop signs and artificially lowered speed limits, doing so would not only not solve the issues, it would knowingly create more hazardous conditions and be a direct violation of federal guidelines. The City will investigate each location against the applicable stop sign and speed limit warrants. However, there are not likely to be many locations remaining in the City where stop signs or lowered speed limits would be warranted. Pavement Markings Pavement markings may be used to guide traffic flow or to visually narrow the roadway. A common application is to add a parking lane edgeline on a street, along with diagonal striping in the "no parking" zones adjacent to intersections and fire hydrants. However, this approach is only possible on two -way streets that are at least 28 feet wide or one -way streets that are at least 20 feet wide. Research indicates that pavement marking tends to slow the fastest drivers on a street due to the psychological narrowing effect. However pavement markings alone do not typically reduce the 85th percentile speed by a substantial margin. And while relatively inexpensive compared to physical changes to the street, the cost of pavement marking can still be significant if a long stretch of street is to be treated. Parking Modifications The addition of parking to a street or to both sides of a street can slow traffic due to the narrowing effect it has upon a street. However, various standards apply depending upon the width of and volume of traffic on the street, to ensure safe access for both resident vehicles and emergency response vehicles. One approach for streets with parking on one side is to alternate the side of the street where the cars are parked in order to create a "chicane" or serpentine effect. Basically this approach serves to help break up a long straight stretch of roadway. One -way Streets A strategy used in gridded areas (e.g. Chicago) is to convert alternating streets to one -way traffic. This is typically used to address severe cut through traffic issues rather than speed issues since the conversion of the street to one -way flow without an accompanying narrowing or addition of parking could actually result in increased speeds.