Workers install safety netting on a new footbridge above the Blue Nile River in the central highlands of Ethiopia. The bridge replaces a stone structure built in 1640, visible in the background. Courtesy of Bridges to Prosperity
Bridges to Prosperity will finish its 100th bridge later this summer, continuing a mission that began in 2001 with a picture in National Geographic magazine.
July 17, 2012— Antahaun stood on the steep rock banks of the Blue Nile River in the central highlands of Ethiopia, several hundred yards upstream from a bridge construction site, with a rope tied around his waist. He had volunteered to jump into the water, and as the swift currents of the Nile tributary carried him downstream, swim for the other shore, being mindful of crocodiles. The rope was essential to enable workers to maneuver the new bridge’s 2-ton cables across the river by hand.
Also on the banks was Avery Bang, A.M.ASCE, the executive director of Bridges to Prosperity, a nonprofit organization headquartered in Denver that focuses on building footbridges in isolated areas. Bang and Antahuan became fast friends during the project, united by a common purpose. The bridge they were building would replace a large stone structure, originally built in 1640, and finally washed out beyond safe repair.
It was this remote site that prompted Ken Frantz to found Bridges to Prosperity in 2001. Frantz, who owned a construction company in Virginia, saw a photo of the 1640 bridge in National Geographic magazine. The bridge has a gaping hole, created when it was bombed during World War II. Local residents resorted to pulling each other across the gap on ropes. Frantz designed a steel truss structure to span the gap.
A photo of this bridge in National Geographic magazine, prompted
Ken Frantz to found Bridges to Prosperity in 2001. Courtesy of
Bridges to Prosperity
Now, nearly a decade later, the group had returned to build a footbridge to make the crumbling stone bridge obsolete. The years had not made the site any more manageable.
“There was about a 10-mile walk from the nearest place where you could drive a car,” Bang says. “So we had to hire a bunch of mules, and load them up with the cement. This, within itself, is just precarious. And we are looking at 200 bags. That’s a lot of trips.”
The steel cables were even more of a challenge. The cables are donated by port operators in the United States, who must retire them from their gantry cranes when they reach 10 percent fray, Bang says. Those cables are load tested and Bridges to Prosperity finds they still surpass the originally specified breaking strength. In Ethiopia, they had a pressing question.
“How do you get that cable to the site? It weighs two tons. It’s ridiculous,” Bang says. “So what we do is we recruit our 60 or 70 best friends, and stagger everyone every 5 or 10 feet, so that you are able to carry that incremental load, but you are relying on the team as a whole. And you parade as one long line for your 10 mile walk. It’s kind of an incredible allegory for what we are doing in general.”
With ropes across the Blue Nile, the same 70 volunteers were able to pull the huge cables across the river, careful not to let the line sag far enough to touch the water.
“You have this predicament,” Bang says. “The river is 60 meters wide and rushing. If you let that cable drop and hit the water, that force dragging that cable is crazy. We have used pulleys, when you have them. We have used cable winches, when you have them. What do they have locally? That’s probably the most Indiana Jones style that we’ve done.”
With the 2 ton cables strung over the 10 m steel pipe towers,
workers begin hanging support members for this suspension
bridge in El Salvador. Cable suspension bridges are a recent
addition to Bridges to Prosperity’s repertoire. Courtesy of Bridges
Later this summer, Bridges to Prosperity will mark an important milestone, commissioning its 100th bridge. The 280 ft span will join the communities of Myange and Kibare in northern Rwanda. Villagers there cross the river to buy and sell goods at local markets. The nearest bridges are 20 km in one direction and 10 km in the other. Several hundred schoolchildren cross the river. During the rainy season, crossing is dangerous or impossible.
“Realistically would you or I detour 20 km out of our way to cross a river?” Bang says. “Or would you just try to wade it?”
Elie Homsi, P.E., a Bridges to Prosperity board member and senior vice president of engineering services for Flatiron Construction Corporation, in Firestone, Colorado, has experienced this dilemma firsthand while scouting bridge locations in Nicaragua.
“When we went on the first trip there scouting for locations, as we are crossing the river as it is right now—in the dry season—we were jumping from boulder to boulder to get across,” Homsi says. “People—to go to work, to go to school, to go to the hospital, to go to the market— they are hopping on these boulders, unless they want to get wet. You slip from time to time. We slipped many times when we were crossing over.”
In many areas where Bridges to Prosperity works, a pronounced rainy season makes crossing the river impossible for as many as six months of the year. This cuts off residents from schools, markets, and hospitals. Children, livestock, and even adults have been swept away and drowned.
“As an organization, what really resonates with me is that this is a piece of infrastructure that leverages all the other good work that other folks are doing,” Bang says.
Before Bridges to Prosperity built this 213 ft suspended bridge
across the Luena River in Zambia, about 250 residents of the
community of Kaoma crossed the river by canoe each day to get
to vital services across the river. Courtesy Bridges to Prosperity
Bridges to Prosperity has worked in 16 countries, primarily constructing suspended—stressed ribbon cable—foot bridges. The bridges are elevated by natural terrain, via stone towers.
“The suspended bridges are the Indiana Jones-style bridges,” Homsi says. “If you have a deep canyon or a ravine, a suspended bridge will work. You just have to anchor it somewhere and let it droop down. As long as it doesn’t droop below the water, you are fine.”
Bridges to Prosperity predominantly uses local supplies for the bridges, which take about one year to complete and cost about $10,000. The organization selects projects to educate and inspire residents and local builders, leaving behind detailed manuals to help with maintenance and the construction of future bridges.
“At the end of the day, we do one thing. And we want to get all the resources together in such a way that we can train people in the countries we work to build bridges without us,” Bang says. “How can we better make ourselves obsolete and work ourselves out of a job? Move on. Find a new place that has a need for infrastructure and not sit there and be that typical aid model.”
A typical suspended bridge features stones from the river and banks, sand sifted from the river for concrete, cement from the capitol city, and rebar and chain link fence safety netting from hardware stores. Local governments are usually tapped for timber for decking and cross members. The cables cross the towers over an automobile wheel, cut in half.
“When we go in and build a bridge, the municipality and the community must contribute,” Bang says. “The community must work for free. If they don’t think this project has value added, and they are not willing to work for it, we have other communities we can help.”
Flatiron Construction helped Bridges to Prosperity expand its repertoire with the addition of suspension bridges, which are much more complex, especially when using local materials in remote locations. Still, being able to employ this type of bridge allows the group to make important crossings in flat locations.
The decking for the bridges is locally sourced timber. The group
finishes each structures with chain link fencing for added safety.
Courtesy of Bridges to Prosperity
“The suspension bridges, they needed to develop,” Homsi remembers. “We had the know-how, we had the engineers, the construction people, the staff to help with that, so we decided to team up with them to help them develop suspension bridges. The mission statement, what Bridges to Prosperity stood for, fit right in with what Flatiron was looking for as a giveback program.”
Homsi says that Bridges to Prosperity has primarily used recycled piping for the 10 m suspension towers, but is working on a design that will use reinforced-masonry blocks, because the materials are readily available and local builders are usually well skilled in the methods.
Although the suspension bridges are “infinitely more complicated,” Bang says they are the only solution for some locations. The organization uses volunteers from engineering and construction companies to develop locally appropriate solutions to the challenges.
Bridges to Prosperity employs program managers, who serve in many roles: building relationships with national and local governments, scouting locations, finding local builders, educating local residents, managing construction, and hosting corporate partners. Netta Ophir, the director of operations, has worked on bridges in Honduras, El Salvador, and Bolivia.
“Looking for sites, I met with the Mayor of Tiquipaya [Bolivia],” Ophir said in written comments to Civil Engineering
online. “ ‘Yes,’ he said to me, ‘we have many communities that need bridges and luckily enough in two days we are going to visit some of those—would you like to join us?’ I happily agreed and just before I left the meeting I asked—‘do I need to bring anything specific with me?’ ‘Nothing,’ said the mayor, ‘only what you need for three days.’ Three days? Well, I packed all I thought I might need—not knowing where we are going, what the weather is like, anything.
“We left early in the morning and drove for five hours on dirt roads and when the road ended— we started walking. ‘Is it a long walk?’ I asked, feeling the weight of my big bag on my back. ‘We are nearly there’ was the reply. Eight hours and nine rivers later, we arrived at the last community on this road. This amazing walk through the jungle, the three days we spent with people living so far out, the way of life I saw there—it will always remain one of my best and most interesting experiences.”
For Luke Smith, S.M.ASCE, the project manager for the University of Iowa Bridges to Prosperity chapter, it was a late concrete placement for a bridge anchor in Nicaragua that he will always remember.
“We brought flashlights out to the site so we could see as we mixed concrete and poured the concrete into the foundation,” Smith said, in written comments to Civil Engineering
online. “We had been working all day and were exhausted. All of a sudden everyone from a nearby house came out and started helping. Really little kids were helping move concrete in containers that weren’t much larger than a cup. It was the cutest thing and it made you realize how much everyone appreciates what you’re doing.”
Homsi says that for each project, a significant member of the community is chosen as the first to cross the bridge.
“The Melara bridge [in El Salvador], the first person to cross was an eight-year-old girl who, during the storm before, got washed away to sea. That’s several miles. And somebody picked her up at sea, alive. She was on her way to school,” says Homsi, who is taking his family on a vacation in Rwanda, to work on the 100th bridge this summer.
“None of our guys who have been down there were not touched,” he says. “Most of our guys want to take time off on their own to go build a bridge down there even if we are not sponsoring it.”