Beyond Design Gonzaga University Engineering Students Get Course In Reality While Doing Design Work On Leg Of Centennial Trail

Standing on a wind-swept ledge above the Spokane River, the engineering students look beyond an abandoned railroad grade and into the future.

The students envision a 400-foot long timber bridge that crosses the river downstream from downtown, from a Central Pre-Mix gravel pit to the West Central neighborhood. They see bicyclists, joggers and parents pushing strollers along an old railroad corridor that would be the final Spokane County leg of the Centennial Trail, which runs from Nine Mile Falls into Idaho.

This vision will get a kickstart this summer when seven Gonzaga University seniors who have been working on the design for the trail and bridge, hand the project over to the Washington State Parks and Recreation Commission, city planners and Friends of the Trail, which will raise money and try to gain support for the project.

The goal is to pick up the existing Centennial Trail at the Meenach Bridge then bring it eastward along the south bank of the river on property owned by Central Pre-Mix. The 1.5-mile stretch of trail would cross the river on the new timber bridge, then continue over an abandoned railroad grade and city streets to the edge of the Summit Property at Summit Boulevard and the river. Developers of Summit would, at a future date, bring the trail east to Monroe Street.

The cost of the trail, excluding the bridge, could reach $500,000, with some of that coming from grants. The state has allowed a $460,000 grant for the bridge, as long as work on the bridge is under way or ready to begin by the end of the year.

For those involved in the project, it’s a chance to bring the trail along one of the two remaining freeflowing stretches of the Spokane River.

The stretch from the Monroe Street Bridge down to Riverside State Park is already designated a wildlife corridor by the city. It’s also one of the few wild rivers so close to a downtown population center, said Doug Pineo, a wildlife biologist with the Department of Ecology.

“That’s the tricky part about designing the trail, it has to be done in a way that won’t damage or diminish the shoreline. This is a classic area. It’s remarkably intact,” he said.

Because of a wintering area for eagles, no construction can occur between Dec. 1 and March 1. Revegetation will be needed after construction, and one or more switchbacks from the bridge to the trail alignment.

“This has been the most challenging section for us to complete,” said Greg Bever, chairman of Friends of the Centennial Trail. “We’ve tried the approach from three different directions and had problems.”

For the Gonzaga students who dedicated nine months of their senior year to the trail, the work has been both gratifying and frustrating.

Sitting around a conference table at Taylor Engineering in north Spokane last month, the students went over what still needed to be done with Mike Taylor, a private engineer who is donating his time to supervise the work.

Still needed is information on flood levels at the bridge site, soil compaction rates and questions on knapweed, a noxious weed that has overtaken the trail in parts. One challenge that remains is how to route the trail so it would not inhibit small animals from reaching the river.

In putting together their design, the students had to be sensitive to slope, vegetation, and any silt washed into the river from bridge pilings.

“You’re putting a public-access facility into an area that’s environmentally sensitive,” Taylor told the students. “That’s something you’re going to deal with the rest of your careers.”

The class had already spent months researching property lines, slopes, shoreline management acts and the various processes involved in city, county and state planning and permitting.

They had to find the weight of the typical Spokane ambulance and calculate that into the load capacity of the bridge.

For GU engineering student Peter Anthony, the project gave him a chance to use skills in research and surveying. Part of his job was looking at the possible alignments, and picking a route that dropped 250 feet to the Spokane River without exceeding 5 percent grade, the maximum allowed under the American with Disabilities Act.

“Until you go out to the site, you can’t understand how steep that can be, and then have to stay within 5 percent, that’s what makes it tough,” said Anthony.

“During the first semester we were all going nuts,” said Kevin Houghton, another GU student. “To me the eye opener was, ‘Wow, a lot goes into this.’ There’s a whole lot more to the project than just design.”

Student Jason Evers said, “It’s amazing how many agencies have to be contacted and how many different people you have to contact to find one piece of information, but it’s important.”

Another thing the students learned was that their views about a project don’t hold as much weight as the groups charged with building the trail and paying for it.

The best design, Taylor tells the students, is one that can be built within budget. For instance, the students talked about incorporating some kind of arches into the bridge as a way to keep with the tradition of the river. They will try, but the final decision on that would be made by others.

“We’re not here to establish that kind of milestone bridge,” Taylor says. “We just want to get the damn trail across the river.”