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5.0 Curbing and <br />Clearances <br />5.1 Purpose of Curbing <br />Curbing must have 3 raised aspect <br />or vertical element. Along the ex- <br />tremities of roadways, curbing con- <br />trols drainage, delineates the edge <br />Of the roadway. deters vehicles from <br />leaving the roadway pavement, and <br />aids in channelizing vehicle move- <br />ments It provides a measure of pro- <br />tection for pedestrians beyond the <br />roadway, permits the control of ac. <br />cess at designated locations. <br />provides lateral support to the road- <br />way or shoulder pavement. and <br />presents an attractive appearance. <br />On the other hand. it may restrict <br />drivers from taking evasive actions <br />required to avoid a collision. <br />5.2 Types <br />There are two general classes of <br />curds: barrier and mountable. Each <br />has distinct features and design de- <br />tails. Although Gasses of curos are <br />usually constructed as separate <br />units. they can be an integral part Of <br />the roadway pavement or driveway <br />apron. SQQ Figure 5.1. Some curbs. <br />constructed separately from the <br />roadway, include 6 to 30 Inch (0.15 to <br />0.75 m) wide gutters. <br />Flush or slightly raised strips are <br />used as lane dividers. as permanent <br />centerlines since Roman times. and <br />as lane lines or pavement edge lines. <br />They are used In areas approaching <br />gores. or as flush smoulder strips to <br />serve some of the functions of a curb. <br />Curos are generally constructed of <br />asphaltic or portland cement con- <br />crete. Other matenals used include <br />granite, blue stone. and steel. <br />BARRIER CURBS <br />A <br />MOUNTABLE cURBS <br />a <br />ry: —1 b°';ei1 <br />0 <br />C <br />414; stops 1.:16 <br />E <br />F G <br />Figure 5.1. Typical Curbs. (1 Inch = 2.5 cm) <br />Source Ref 3. 0 358 <br />Page 10 <br />