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1 Feb. 8, 1983 BIKEWAYS ■�„ -22- H. CLEAR ZONE (distance from bikeway to traveled way) For on -road bikeways refer to the bikeway design - tables to assess the road suitability for bicycle travel, The tables will also enable "pretesting" of shoulderwiden- ing and surfacing. Bike traffic must flow the same direction as adjacent motor vehicle traffic. Two-way bike traffic on one -side of the road is not permitted. For off -road. bikeways, there are two categories: roads without curbs and roads with curbs. The proper set back from the traveled way is an important consideration for the designer because operation of the facility is de- pendent upon adequate separation from each respective travel mode (motor vehicle, bike, pedestrian) and sta- tionary objects (poles, signs...). See Figure G. - I, DRAINAGE For bike routes and lanes the existing roadway drain- age is normally adequate. However, on curb and gutter sections a check of ponding depths should be made and corrective action proposed if depths are significant- This may entail improved grate designs or wider bike lanes. On off -road bikeways, the surface of the bikeway should have a cross -slope of two percent for the proper irainage. Sloping in one direction usually simplifies longi- tudinal drainage design and surface construction, and accordingly, is the preferred practice. Ordinarily, surface irainage from the path will be adequately dissipated as t flows down gently sloping terrain. However, when the ukeway is constructed on the side of a hill, a drainage iitch of suitable dimensions may be necessary on the uphill ide to intercept the hillside drainage. See Figure H. Cul- ,erts or bridges are necessary where a bikeway crosses a lrainage channel. Sizing of the required waterway opening hould be determined by a hydraulics engineer, Minimum ,ulvert size used for bikeway drainage should be 18 inch. Hameter. Drainage inlet grates on bikewaysshallhave openings .arrow enough and short enough to assure bicycle tires rill not drop into the grates regardless of the direction of dcycle travel, Where it is not immediately feasible to re - lace existing grates with standard grates designed for icycles, 1 inch x 1/4 inch steel cross straps should be relded to the grates at a spacing of 6 inches to 8 inches n center, to reduce the size of the openings. See Standard lates 4151 and 4152 for acceptable designs of grates, (ROADS WITHOUT CURBS) R/W iBIKEWAY 20'MIN. TRAVELED WAY 2- MIN.PAVE 1ROADSWITH CURBS)' 8' STREET MIN. 4- MIN. PAVED BIKEWAY "PROVIDES ROOM FOR SIGNS, POLES, 'ETC.. FIGURE G 2% Bikeway I 2% 1. Variable Bikeway FIGURE H i