1A, US 10CR 96 Grade Separation & CSAH 96 Improvements - Project Update

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SC>LTC)N & I'/IENK, INC@ Consulting Engineers & Surveyors 12224 Nicollet Avenue · Burnsville, MN 55337 Phone (952) 890-0509. Fax (952) 890-8065 www.bolton-menk.com MEMORANDUM DATE: August 5, 2009 TO: Kristine Giga, P.E. - Civil Engineer Ron Moorse - City Administrator City of Arden Hills FROM: Christopher S. Chromy, P.E., P.T.O.E. Senior Transportation Engineer RE: Highway] 0/96 Grade Separation Project Feasibility of Pedestrian Crossing of CSAH 96 BMI Project No. T42.222335 Per your request, I have completed a conceptual analysis of the feasibility of grade-separated pedestrian crossings of CSAH 96, east of TH ] O. My findings and recommendations are summarized below: Background As part of the TH 10/CSAH 96 grade separation, the city is interested in enhancing pedestrian connections across TH 10 and CSAH 96. The proposed TH 10/CSAH 96 project enhances pedestrian crossing of TH 10 by providing a trail and sidewalk along CSAH 96 as it passes under TH 10. Pedestrian crossings of CSAH 96 are proposed at signalized intersections. At signalized intersections, marked crosswalks and ramps, pedestrian push button and signal heads, and count-down timers will be provided with the TH 10/CSAH 96 project. Signalized intersections are proposed on CSAH 96 at Prior A venue and Old Hwy 10. A future signal is anticipated at CSAH 96 and Rice Creek Parkway. Grade Separation Alternatives and Cost Several alternatives were evaluated for grade-separated pedestrian crossing of CSAH 96. These included providing additional width on the proposed northbound TH ] 0 bridge, lOx 14 box culvert underpass, and stand alone pedestrian bridge. TH 10 Bridge - As part of the TH 10/CSAH 96 project, CSAH 96 will be lowered by approximately 22' and two new bridges will be constructed to carry TH ] 0 vehicle traffic over CSAH 96. The bridges will have a span length of approximately 275'. One of these bridges could be constructed with additional width to carry a multiuse trail separated from vehicle traffic. For a 10' trail crossing, approximately 18' of additional width would be necessary on the bridge. At an approximate unit cost of $160/sq.ft., the additional bridge width is estimated to cost nearly $800,000. In addition, to make the crossing accessible to pedestrians and bicycles along CSAH 96, trail and sidewalk extensions of approximately 600 feet would be necessary on both sides of CSAH 96. This could likely be accomplished in the southeast quadrant of the intersection; however it is unlikely in the other three quadrants due to the proximity of proposed ramps and roadways. This concept is not recommended for several reasons. First, the skew of the TH 10 bridge results in a longer span than necessary to cross CSAH 96 and results in a higher cost than a perpendicular crossing.