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Mr. Patrick Klaers <br />December 11, 1996 <br />Page Two <br /> <br />2. Pedestrian Underpass <br /> <br />The second option to provide a grade-separated crossing of CSAH 1 is a <br />pedestrian underpass. A 12-foot wide by 8-foot high box culvert was used to <br />establish a pedestrian underpass of CSAH 1. <br /> <br />DESIGN REQUIREMENTS <br /> <br />It is recommended that any proposed construction comply with standards included in the <br />Americans with Disabilities Act (ADA). ADA Standards require that for ramps with <br />slopes of 12:1 or greater, that 5-foot landings be provided for every 30-inches of rise, or <br />for every 30-feet of ramp. This standard would be applicable for both overpass ramps <br />and underpass ramps. <br /> <br />1. Pedestrian Overpass <br /> <br />For the construction of an overpass, AASHTO requires a vertical clear space of <br />17' - 4" between an overpass and road surface. With a proposed road width of <br />up to 72 feet, it has been estimated that the length of an overpass would be <br />approximately 90 feet. Based on the proposed centerline elevation of CSAH 1, <br />and existing elevations on the north and south side of CSAH 1, ramp lengths <br />would need to be approximately 245 feet and 280 feet in length to meet ADA <br />Standards. <br /> <br />As stated before, two options are available to provide access to a proposed <br />overpass. A structural ramp could be constructed directly over the existing City <br />Trail, with no additional right-of-way being required. To construct a ramp with <br />embankment, maximum side slopes of 4:1 would need to be maintained to provide <br />for the stability of the embankment. The width of the embankment at ground level <br />would be approximately 150 feet, exceeding the 100 feet of right-of-way width <br />that is presently available. Due to the limited right-of-way available, retaining <br />walls would need to be constructed on both sides of the embankment to <br />accommodate construction of the ramps within the 100 feet of right-of-way. <br />Retaining walls, approximately 17 feet in heights, would also be required to serve <br />as abutments at each end of the overpass. <br /> <br />2. Pedestrian Underpass <br /> <br />It is assumed that a 12-foot wide by 8-foot high box culvert would be used to <br />construct a pedestrian underpass crossing of CSAH 1. Approach ramp lengths, <br />based on existing elevations, would need to be 175-feet and 125-feet in length on <br /> <br />230/213-0917.dec <br /> <br /> <br />