SCH Number 2024121192

Project Info

Title

Alamo River Trail Trestle Bridge

Description

The Alamo River Trail Trestle Bridge was constructed around circa 1904 with a length of about 350 feet, is an open deck bridge consisting of several short spans and is supported by a system of splayed vertical structural elements. A particular feature of this trestle is the apparent composite of both a timber bent system at both ends and a steel space truss system in the middle. The steel truss occupies the mid one-third of the length of the trestle and is bolted with rivet type connections. The steel rails have long been removed by A & K Railroad Materials for salvage use. As such, the remaining transverse timber beams, spaced at about 2 to 3 feet on center, form the current main top surface of the deck. These transverse beams are about 7-1 /2 inch wide by 9-1/2 inch deep over the longitudinal wood girders and increase to 9-1/2 by 16 inches over the top chords of the steel truss. On each end of the transverse beams, a 3-foot-wide metal grating sidewalk supported by double cantilevered wood rafters provides access and adds to the total width of the trestle top deck. A set of 3'-6" tall vertical metal angles at about 3' on center are bolted to the tips of the double cantilevers to form a handrail system with horizontal cables. In August of 2009 a fire occurred in the vicinity of the trestle bridge which resulted in significant damage. A 2010 visual review of the trestle bridge found that the deck, support cross beams, grating, railings, and bents were completely damaged and in need of full replacement. The trestle bridge repair will result in the replacement of the damaged structural bent timbers, structural cross beams, and other structural components. More specifically, the rehabilitation will consist of the demolition and replacement of the damaged portions of the bridge ( approximately 1,000 square feet), and the installation of 3,500 square feet of bridge decking suitable for nonmotorized trail users, 350 linear feet of Americans with Disabilities Act (ADA) compliant bridge railings suitable for pedestrians and bicycles, and 350 square feet of bridge landing suitable for the transition between the bridge and the existing Alamo River Trail. The damaged structures will be replaced with timber, when feasible, to match the nondamaged portion of the bridge and restore the aesthetic appeal of the bridge. The improvements will result in the repair and conversion of the existing trestle bridge into a multimodal pathway suitable for non-motorized users including pedestrians, bicycles and equestrian traffic. The project will also include improvements to the existing Alamo River Trail aimed at extending the trail to connect to the trestle bridge walkway. The trail improvements will consist of an 8-foot wide, 12 inch deep, class 2 base trail continuation section from the east edge of the Alamo River Bridge to the existing 8-foot-wide plain cement concrete trail. Additional improvements include trail side amenities consisting of 45,000 square feet of mulch, fifteen (15) trees from fifteen (15) gallon containers, thirty-five (35) each of bushes, shrubs, and grasses, six (6) benches, two (2) informational kiosks, four (4) "No Motor Vehicles" signs, and one (1) funding acknowledgement sign. All proposed landscaping will comply with the State Model Water Efficient Landscape Ordinance (MWELO) and have its own irrigation consisting of drip fittings and tree bubblers.

3 documents in project