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ITEM 4.9. <br /> <br />Howard R, Green Oompany <br />QONSULTING ENGINEERS <br /> <br />October 14, 1998 <br />File: 803450J-0060 <br /> <br />CONSULTING ENG]NEER~ <br /> <br />Formerly MSA <br />Consulting Engineers <br /> <br />Honorable Mayor and City Council <br />City of Elk River <br />13065 Orono Parkway <br />Elk River, MN 55330 <br /> <br />RE: TRUNK HIGHWAY 169 PEDESTRIAN BRIDGE <br /> <br />Dear Council Members: <br /> <br />As you are aware, we have been working on the federal paperwork and beginning the design on <br />the Trunk Highway 169 pedestrian overpass. As we get further into the design, there are a <br />number of issues that we would like to make the City Council aware of, and get some input. <br />Most of these regard the type of construction materials and style of bridges. We have a short <br />videotape (approximately 10 minutes) of several bridges from around the Twin Cities area that <br />we will show at the City Council meeting. <br /> <br />Several of the key considerations that we would like some input into are as follows: <br /> <br />A. MATERIALS <br /> <br />There are basically three materials that a pedestrian bridge can be constructed of. <br />These are steel, concrete, and wood laminate. Generally, steel is the least expensive, <br />with wood laminate the most expensive and concrete somewhere in the middle. <br /> <br />B. STYLE OF CONSTRUCTION <br /> <br />The look of a bridge is dictated by the design style, pier type, material selection and <br />choice of aesthetic elements. <br /> <br />There are several styles of construction including continuous span, through girder, <br />through truss, and pony truss. A brief description of each of these is as follows: <br /> <br />Continuous span: This is probably the most common style of pedestrian bridge. This is <br />where the material used for the beams is underneath the floor of the pedestrian bridge, <br />and the handrail and fencing are attached to the floor of the bridge. This type of bridge <br />has the greatest overall height. <br /> <br />Through girder: The girders are two L-shaped beams placed to form a U shape. The <br />walkway is within the U. Because of the long spans required to cross a four-lane <br />highway, the beams get quite deep. To reduce the overall height of the bridge, the floor <br /> <br />O:~ROJ\803450j\0060~450-0902.oct.doc <br /> <br /> 1326 Energy Park Drive · St. Paul, MN 55108 ° 612/644-4389 fax 612/644-9446 toll free 888/368-4389 <br /> <br /> <br />