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| Timber Bridges & Walkways |
Southern Pine Lumber has been used for bridges, walkways, and boardwalks for hundreds of years. The great Atlantic City Boardwalk was built with preservatively treated Southern Pine lumber in 1867. To meet today's environmental requirements, designers are following a trend to span wetland areas with timber bridges and elevated wood boardwalks.
Industry standards have been developed to insure long-term performance of treated wood. New advances in preservative treatments, and in design and construction techniques, make lumber a cost-effective construction material for bridge applications. See typical examples below.
Order or download PDF version of Aquatic & Wetland Structures design and construction guide. To find a source of supply, go to the Product Locator.
For further information on timber and glued laminated bridge construction, contact:
Basic Design Guidelines for Walkway Construction
Elevated walkways are an excellent alternative for wetland filling and the associated negative environmental impacts. Meandering elevated walkways through forests, wildlife sanctuaries and nature preserves offer pedestrians and cyclists opportunities to view environmentally sensitive areas from a new perspective, while allowing minimal impact on the natural activity of such an area.
Walkway construction in wet-lands and other environmentally sensitive areas is a complex process with many variables - it requires extensive knowledge of local conditions and should only be undertaken by qualified professionals.
Considerations should be given to natural surroundings and aesthetics, loadings, codes and construction practices, materials and soil analysis. Do not hesitate to seek out experienced design professionals and look at examples of their work. Use only licensed, experienced contractors. Ask for pictures and references. Visit past projects and talk to recent customers.
The proper evaluation of soils is critical to design and performance of the walkway structure. Sandy (granular) soils are usually quite predictable and yet are subject to scour and erosion. Clays (cohesive soils) may not be consistent in a given area and may vary widely within a single project. Even when viewed by an experienced design professional, soil analysis without benefit of testing by a qualified soil testing laboratory is approximate at best. The relatively low cost of a local certified testing lab is easily offset by the advantages of accurate quality and strength data.
Properly specified Southern Pine lumber should give long performance under all anticipated conditions. Materials that do not meet or exceed specifications should be rejected. Substitute materials may appear to offer short-term benefits, but such savings may translate into higher maintenance and repair costs for the owner.
Lumber is supplied in increments of two feet. To avoid unnecessary cutoff and waste, designs should be developed to utilize the full length. Remember that any field cuts damage the preservative effectiveness of treatment. Whenever possible, have cuts such as mortises or radius milling of edges completed prior to treatment or at least dip or brush these surfaces with copper naphthenate prior to installation.
One of the most aesthetically important aspects of a walkway is the handrail system. The handrails provide necessary safety for children and the handicapped and offer an eye-pleasing site when designed properly. Note common practice of leaving 1" to 2" space between decking and bottom rail to aid draining and cleaning of deck.
An emerging practice is the use of stainless steel screws in deckboards. This allows for the removal of screws and turning over of deckboards after a fixed period of time, resulting in a fresh deck surface at low cost.
Glued Laminated Pedestrian Walkways
Structural glued laminated timber (glulam) is a popular construction material that is frequently used for pedestrian bridges and walkways. North American architects engineers, designers and contractors have been specifying glulam for more than half a century. The demand for Southern Pine glued laminated timber continues to increase because of its high strength, natural beauty, competitive cost, dimensional stability and is readily available in a large range of sizes and shapes.
Glued laminated timber can be easily preservative-treated for wet service conditions and can satisfy virtually any design while providing fast erection and competitive in-place costs, hence its growing acceptance and use in pedestrian bridges and walkways.
Golf Cart and Small Vehicular Bridge Applications
Golf courses around the country are experiencing genuine success by expanding and incorporating elevated cart paths and bridges made of preservatively treated Southern Pine lumber. Club developers like the timber cart paths and bridges because their natural look blends in with the environment and they eliminate the need for fill, thus providing for easier access to obtaining environmental permits.
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