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March April, 2003

 

 

 

 

Bridge Over Troubled Waters

Janicki Logging uses Rapid-Span solutions

By Kurt Glaeseman

Need to bridge a gap but also need to balance a cost-effective budget, a shrunken calendar, a site-specific purpose, and a volume of environmental rules and regulations? Take heart. Bridge building technology is changing, and there may be an option tailor-made for you.

It wasn’t too long ago that the logging company simply came up with the necessary bridge — a rudimentary log structure or an installed culvert or even a decommissioned railroad flat car decked as a bridge. In some cases the bridge never got beyond theory — if the roadbed was solid enough, loggers could simply ford a stream and avoid the complication entirely.

The new bridge
Things have changed radically in the past two decades. As Paul Clements pointed out in his seminar on Road Maintenance and Drainage at the Oregon Logging Conference, mixed land usage has created some real challenges. A road, and the bridges thereon, may start as a logging road, then be considered a farming road, and eventually be an access road for hunters and fishermen or even a hiking trail. But the first guy in is often a logger, and a big responsibility rests on his shoulders. He usually does the building, even though his duration may be relatively short, and the roads and bridges remain an essential element of a managed forest.

Today’s options
One of the big issues facing a bridge builder today is the environmental concern for fish passage where roads cross streams. Jim Paul, a Forest Hydrologist from Salem, Ore., lists six possible options for logging traffic that must cross a fish stream:
• Remove or abandon the stream crossing and find an alternate route. • Ford the stream if traffic is infrequent and there is a solid bedrock as a base.
• Simulate a streambed with an embedded culvert.
• Install a bare culvert.
• Develop a hydraulic design of weirs and baffles.
• Span the channel with long or short span bridges and open bottom arches.

In some cases these options are not options at all. A logging company usually has a reason for a certain route, and a secondary detour is simply out of the question. Conditions for repeated fording of a stream are rarely ideal. Hydraulic designs using weirs and baffles are technically challenging and often require more expertise than is readily available. Surface and shrunken culverts have usually been the bridge of choice, but fish biologists have observed three basic problems with this: Fish must cope with high water current velocities or sudden velocity changes, with significant jumps to the culvert inlet or outlet, and with unpredicted shallow water. Often the only viable option left is the installation of a channel-spanning structure.

The Wallace Creek challenge
Rob Janicki, co-owner of Janicki Logging, found the ideal solution for his bridge-building project over Wallace Creek, north of Sedro-Woolley, Wash. Janicki got the bid from the Forest Service to replace an existing bridge in the summer of 2002. First he had to dismantle the old bridge — 90- foot logs and some obsolete decking. Janicki worked closely with Peter Wagner, a Forest Service Engineer, and with Paul King, an Engineering Manager from Rapid-Span, a B.C.-based firm. The new bridge project presented some interesting challenges.

The bridge would ultimately be used for hikers headed up to several remote lakes, but first it would be a working passage, wide enough and sturdy enough to support standard timber practice logging. They needed a 95-foot span over Wallace Creek. It was 40 feet down to the water, with steep cliffs on both sides. Workers could get in from only one side, and there was no room for a crane. Originally the Forest Service wanted to repaint some existing old riveted steel girders over a 50-foot deep chasm and place a wooden deck on top.

Janicki, Wagner and King came up with a modified solution. Instead of refurbishing the old girders and coping with potential danger from lead paint, they decided on the composite steel girder system. A slightly longer bridge would keep the supports further away from the edge of the creek. The new girders were much lighter than the riveted originals, which made it possible for Janicki to use his innovative skyline system to lift the girders to the other side of the creek. The Forest Service was very happy with this alternative: they had a brand-new product that met all the up-to-date codes of the industry.

Teaming up
Janicki made do with his logging equipment. He ran a skyline across and used a John Deere 550 with winch as haulback in conjunction with a D7 CAT with winch on the mainline. It took them four hours to yard the bridge in place, and according to Janicki the whole operation went smoothly: "We used steel cages with guards behind them to create a retaining wall and then set the bridge on top.

It went together fast; it looks good; and I enjoyed working with Peter, who helped design the bridge, and with the folks from Rapid-Span, who created a very nice product." The traditional log stringer bridges were often high maintenance structures that lasted little more than ten years. As large logs became more rare, and subsequently more valuable, the option has been to use maintenance free steel girder bridges that can span farther, be placed in less time, hold heavier loads, and last from 60 to 70 years. The speed of installation (rarely more than two days) has become a strong selling point, but portability is becoming more and more of an issue.

Often a bridge must be decommissioned when access to a particular site is no longer considered appropriate. Rapid-Span does about 300 steel bridges a year and is a relatively young company. Bob Malboeuf started out as a bridge installation contractor, but he bought a shop and began to concentrate on actual bridge building. Malboeuf died in 1996, but business was already booming, so local investors bought the company, purchased more equipment, and enlarged the shop. Paul King remembers the early mission statement: "to make a simple system for extremely remote locations under the worst conditions imaginable."

Of course the company had to adapt to the changing times. At first they used steel girders with timbered decks, but for environmental reasons had to move away from creosoted timber. Pre-cast concrete deck systems seemed practical. These pre-cast concrete decks became an integral load-carrying part of the structural system, allowing for smaller steel girders… and a smaller price. Peter Bellos, in charge of Special Projects and Sales at Rapid-Span, points out that with two plants containing over 40,000 sq. ft. of shop space, the company has plenty of space for automated machinery dedicated to the fabrication of welded plate girders and the assembly of bridge components using maintenance free weathering steel.

The pre-cast concrete facility can produce bridges, decks, and abutments. Portable bridges with non-skid steel decks, steel girder bridges with pre-cast concrete, or timber decks and pre-cast slab bridges are all available. "What we can’t supply," laughs Bellos, "is a resident troll to live under the bridges. At least not yet!"

TW

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This page was last updated on Tuesday, September 28, 2004