Installation Procedures
Fiberglass bridges from E.T. Techtonics can be assembled and installed in a variety of ways depending on the difficulty of your site. Spans can be shipped to you:
Fully Assembled: The span will be delivered to the nearest point accessible by truck. While a small crane (or helicopter) will be needed to unload, the lighter weight of PRESTEK spans means smaller lifting equipment can be used. In most cases, decking will be shipped loose to minimize lifting weight. Depending on location, shipping cost will be higher. Not for volunteers.
Partially Assembled: Individual trusses are assembled, but all connecting crosspieces, bracing, and deck are shipped loose. This saves assembly time on site, but more helpers are needed to unload and move the trusses. Carts can sometimes be used to roll the trusses to the job site. Not suitable for moving long distances or over rough terrain.
In Component Parts: This is our most common form of shipment. Components can be unloaded by as few as 2 workers, usually at the trail head or a nearby staging area. Because no equipment is required to unload, bridge arrival does not need to be coordinated with the bridge assembly. When you are ready for assembly, volunteers or park crews carry the components to the bridge site. No site is too remote. We often have components carried several miles or more on park trails. Once everything is at the bridge site, the bridge is easily assembled using standard hand tools. Depending on span length, bridges can be installed by park maintenance crews, volunteers, or local contractors. Short spans up to 40’ can usually be built by as few as two or three workers, in less than a day.
Assembly Tools Required
Most bridges are constructed with no more than a socket wrench and a few common hand tools. All components arrive precut and predrilled, and customized assembly instructions with drawings are provided to show exactly how to assemble the bridge onto your foundations. Typical connections are ¾ inch diameter A307 hot dipped galvanized bolts. All hardware required to assemble the span is included with the shipment. Just line up the holes, insert a bolt, and tighten the nut. Most spans are designed to be assembled without any power equipment. A list of recommended tools required will be included in the assembly instructions.
Mounting Device
Stainless steel mounting clips are provided, to connect the bridge to your foundation. An anchor bolt placement drawing will be provided to assist you in preparing your foundation to line up with our mounting clips. The number of anchor bolts required will depend on the bridge design.
Typical Bridge Erection in Remote Sites
Short Spans—In most cases, short spans (up to 50’) can be quickly installed by volunteers or work crews by first assembling the two trusses adjacent to the stream bank. Two workers can assemble both trusses of a simple 40’ bridge in an hour or so. Then a larger crew will be needed for a short time to carry or pull the two trusses across to the other side. (A crew of 7 or 8 people can carry a 40’-0 truss for short distances.) After standing the trusses up on the foundations, crosspieces and bracing will be bolted on underneath to connect the two trusses together. This can take several hours if all work must be done from deck level, but will be faster if some of the bridge can be reached from below. Finally, deck & safety rails are installed. Short spans are typically installed by a small crew in about one day.
Long Spans on shallow sites—On shallow sites the easiest method is to construct several temporary supports in the streambed using construction lumber or commercial scaffolding, and then build the bridge in place. Bottom chords, posts, diagonals, and top chords are sequentially added until the bridge is fully constructed on your foundations. Then supports are removed and decking is added. A step-by-step set of assembly instructions will be provided, and this type of assembly is appropriate to volunteer groups with experience using hand tools. An 80’ foot span can be easily assembled by this method, with a small work crew or volunteers, in about 2-3 days.
Long spans on deep sites—Installation in these locations is best done by experienced trail crews or other skilled workers. The usual method in forest locations is to assemble the trusses adjacent to the site and pull them across individually by use of “high lines” attached to nearby trees as shown below. Rigging experience is required. In other locations, it may be possible to bring in a small crane to lift the assembled span into place on the foundations. On some very difficult sites, a small helicopter lift may be the best method.
Splices
Many spans are shipped with splices, to minimize component weight and aid in transporting components into remote locations. Bridge splices are easily installed during construction, using the same hand tools used for bridge assembly.