Ecuador's Bridges: Puente Rio Sandima (2)

Another view of the Puente Rio Sandima. This photo was taken at dusk and looks like an example of magical realism with its strange colors, intricate textures, and abundant vegetation.

 The abutments look discolored and older than the current superstructure. They may have been from an older bridge that deteriorated or had it's superstructure washed away by a flood.

The vertical members are attached to floor beams that support girders and the steel deck. The abutments include new shear keys.

Ecuador's Bridges: Puente Rio Sandima (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Sandima (1)

Let's study one last bridge by Walter Yanez.  To get to Puente Rio Sandima we drove on a dirt road into a rich agricultural region.  A woman charges a small toll to go down this road.  Walter said that he build the single-span, pony truss superstructure and that someone else built the abutments.  The superstructure was brought in by truck and placed on steel plate bearings on the abutment seats.  The bridge is about 12 meters long and about 3 meters wide. It has a steel riding surface and it was the only one of Walter’s bridges that I saw that was designed for light truck traffic.   Note that the deck has a textured surface as well as long slots to promote drainage.


Walter is a really hard worker and he is very proud of his bridges. That's Walter in the photo standing with his hand on his hip. He's traveled throughout Latin America, sometimes with his friend Toni Ruttimann and sometimes on his own, building bridges. Some of his bridges we're built after disasters like floods and some were built to help the rural poor. 

Ecuador's Bridges: Puente Rio Sandima (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Dano Canyat sobre el Rio Bua (2)

Unlike the east end of the Rio Bua suspension bridge, the west end has no back suspenders and no deck. Both steel towers are anchored directly into the foundation. The suspender cables are precut, passed through steel pipe floor beams, and wrapped around the  25 mm diameter steel suspension cables.  

This area is well-travelled and the river is often filled with men and women washing their clothes and with children playing. It reminds me of the novel 'An Accidental Man,' by Iris Murdoch where most of the community's activities take place against the backdrop of the communal baths.

Ecuador's Bridges: Puente Dano Canyat sobre el Rio Bua (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Dano Canyat sobre el Rio Bua (1)

Each of Walter's bridges is a little different. This structure has backstays on the east side that support the deck past the tower. This is a good solution when you need an extra long deck, because you can still carry it using back stays hanging from the suspension cable.

The towers are 15.5 ft tall (I have trouble sticking to meters). The main span is 141 ft, the east span is 48.3 ft, and the west tower to the west anchorage is 50.2 ft. The deck (between the tower legs) is 5.33 ft.

This is another suspension bridge with fixed towers and a short main span. It's only a few miles from the Bella Vista Bridge and it's also over the Rio Bua, which seems to be running a little faster at this location (0° 8.61' S, 79° 24.07' W).

This bridge looks in better shape than Bella Vista, even though they were both built around the same time (in 2004). Note the bamboo used as handrails on this bridge.

 Zoe's husband Ricardo is strolling purposefully across this bridge in the photo. We'll take another look at this interesting bridge tomorrow.

Ecuador's Bridges: Puente Dano Canyat sobre el Rio Bua (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Bella Vista sobre el Rio Bua (3)

Another view of the Puente Bella Vista sobre El Rio Bua. This structure is not as elegant as some of Walter's other bridges. The towers are short, it's over a smaller river, and it doesn't have a hand rail or fencing. However, it seems very well used by the community.

There are steps so that people can do their laundry under the shade of the bridge. The women have wooden paddles to beat the clothes against the rocks. It seemed like a good location for socializing while work is being done.

Ecuador's Bridges: Puente Bella Vista sobre El Rio Bua (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Bella Vista sobre el Rio Bua (2)

A view from the other side of Puente Bella Vista sobre el Rio Bua.

Bridges to Prosperity (B2P) asked me to study Walter's bridges because they thought the design might prove useful in situations where the Helvetas designs were too expensive or inappropriate for the site. 

I provided a report on what I had learned along with schematics on several of his bridges but I never heard if my work proved useful or if they ever adopted Walter's and Toni's design.

Ecuador's Bridges: Puente Bella Vista sobre el Rio Bua (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Bella Vista sobre el Rio Bua (1)

Another bridge designed and built by Walter Yanez in Ecuador. The main span is 57.8 meters long and the towers have fixed bases (rather than the pinned bases used on the longer bridges). Walter must have felt that the shorter towers could resist the resulting bending moments and shears.

Bella Vista is the name of the community that helped build this bridge. It was surveyed by Walter in 2003, checked by Toni, and built by Walter and the community in 2004.

The bridge seems less well-maintained or maybe it's just more used. The last few planks of the wooden deck on this side of the river are missing. However, it sees plenty of traffic and I noticed that the women of the village liked to do their laundry on the stones under the deck.

I took the dimensions of this bridge. It uses 3" diameter pipes for the floor beams and 6" diameter pipe for the towers. The other dimensions are shown in the drawing below. Note that there is a short stairway that people must use to descend to the ground at the far side of the bridge.

Ecuador's Bridges: Puente Bella Vista sobre el Rio Bua (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Cupa (2)

The Rio Cupa bridge gets a surprising number of visitors in the course of a day. The heavy traffic explains why they first tried to build a vehicular bridge at this site.

The towers are 9.2 meters high and the deck is 1.3 meters wide. I'm standing at the west anchorage.  It's 23.9 meters to the west tower, 85.1 meters to the east tower, and 19.8 meters to the east anchorage. The east anchorage is 2 meters higher than the west anchorage.

The site was surveyed and a preliminary design was proposed by Walter in July of 2004. The design was checked by Toni Ruttimann and the bridge was built by Walter and the community of 5 de Agosto, Union Manabi later that year.

Ecuador's Bridges: Puente Rio Cupa (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Cupa (1)

Equestrian loads are not usually addressed for pedestrian bridges.  The load from a cantering horse can be several times larger than a pedestrian load. Still, this bridge (across the Cupa River) regularly carries horses without undo fatigue or displacement.

The Puente Rio Cupa is another bridge designed and built by Walter Yánez. Originally, the village (Union Manabi) was hoping to build a vehicular bridge across the river. You can still see one of the abutments behind the bridge in this photo. Either they ran out of money or they had trouble building such a long span across the river.

Walter's bridge is an 85 meter long suspension bridge supported on pinned base towers. We'll take another look at this interesting bridge tomorrow.

Ecuador's Bridges: Puente Rio Cupa (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (6)

This photo shows one of the anchorages for Puente Rio Baba. Walter (the designer and builder) is standing with one foot on the suspension cable and Zoe (from Bridges to Prosperity) is sitting next to him.

A metal frame made from pipes is embedded in the concrete of the anchorage and a length of cable is wrapped around the metal frame and extends outside the concrete. Walter weaves this cable into the suspension cable (he showed me how to do it, but now I can't remember).

Walter took me deep into the jungle to see how he surveyed the riverbanks near a village to see if he could build a bridge at the site. We traveled up and down the river in a dugout canoe with campesinos using machetes who clear a path for us.

Everyone was very grateful for Walter's work. Sometimes farmers would cut down bunches of bananas and other fruit and throw them into the back of Walter's truck. Once, we spent several hours surveying, and then Walter had to tell the villagers that the river was too wide for one of his bridges.

Ecuador's Bridges: Puente Rio Baba (6) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (5)

A view of the bottom of one of the towers for Puente Rio Baba. The pins for each tower (and a metal frame for each anchorage) are placed in the concrete before it is cured. Then the towers can be raised (usually with the help of a truck) and the suspension cables are attached to the top of the tower saddles and to the anchorages. Two or three struts provide lateral stability to the towers.

As I previously mentioned, the suspension cable has the same angle on each side of the tower so that the longitudinal force on each side of the tower is equal.  Also note that the hangers are made from a single cable that descends from one suspension cable, goes through a hole in one side of the floor beam, back up through a hole in the other side, and back up to the other suspension cable.

Ecuador's Bridges: Puente Rio Baba (5) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (4)

I've mentioned that a bridge looks very different from under the deck. Some bridges are more attractive from below, but they are usually not suspension bridges. However, the underside provides a lot of information on how the bridge works.

The floor beams for Puente Rio Baba are steel pipes hanging from the suspension cables. Timber stringers are staggered from side to side so that both ends of the stringers can be supported on the floor beams.

I believe that the villagers were responsible for supplying the timber used on Walter's bridge. After he completes his survey, he provides the villagers with a list of what he needs and if it's not there when he returns, he just drives on to the next village and the next bridge project.

Building these bridges is a communal process. It is quite common for villagers to have heated debates about the pros and cons of building a bridge. A firm commitment from the villagers is needed before Walter will begin a project. Because, the river can become dangerous or impassable during the rainy season, the standard of living for most people in the village will improve once they are able to safely cross the river.

Ecuador's Bridges: Puente Rio Baba (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (3)

After the anchorages and tower foundations have been poured and cured for one of Walter's bridges, then it can be assembled in a couple of days. The suspension cables are draped over the towers and attached to the anchorages. Then one or two people sit up on the suspension cables and attach precut stays every two meters. Floor beams are connected to each pair of stays and timber stringers are supported on the floor beams. Finally, wooden planks are laid on top of the timber stringers, hand railing and fencing is attached to the stays, and the bridge is complete.

For Puente Rio Baba, the deck also had to be anchored to the side of the cliff and steps were laid to help people get to the top. This isn't a bad solution when one bank is 40 meters higher than the other.

The deck is 102 meters long but the towers are 130 meters apart. The lower tower is 6.8 meters tall and the upper tower is only 3.9 meters tall. The anchorage is 23 meters behind the lower tower but only 9 meters behind the upper tower.

Toni wrote some software that Walter uses to determine the sizes of the towers and the lengths of the cables so he can cut everything out before construction begins.

We'll take another look at this interesting bridge tomorrow.

Ecuador's Bridges: Puente Rio Baba (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (2)

This bridge is a somewhat unusual design for Walter because it has one tower 40 meters above the other on a cliff on the other side of the river.

Walter began building bridges with Toni Ruttimann who had a strong desire to help the poor. Because neither Walter nor Toni were engineers, they came up with a very safe bridge design. As long as they maintained some simple geometric relationships and kept the span length below about 100 meters, they knew their bridges would be very safe. The towers were pinned and the force on each side of the tower was kept equal by making the angle of the cable the same on each side of each tower.

I called this bridge Puente Rio Baba but looking at my notes, I found that Walter called it Puente Santa Marianita, which is the name of the community that helped build the bridge. This bridge is in the country of Ecuador, the province of Pichincha, the canton of Santo Domingo, the parish of El Esfuerzo, and the community of Santa Marianita.

The Catholic Church plays a large role in rural life in Ecuador. We were sometimes accompanied by a priest to visit a bridge and then we would drive slowly because so many people would run out of their house to say hello or ask something from the priest.

We'll take another look at this bridge tomorrow.

Ecuador's Bridges: Puente Rio Baba (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Ecuador's Bridges: Puente Rio Baba (1)

I thought we might continue traveling south to look at some interesting bridges that I photographed in Ecuador.


In September The Happy Pontist devoted several blogs to voluntary organizations that provide bridges to help the rural poor. Coincidentally, I had recently spent some time in Ecuador for Bridges to Prosperity studying inexpensive bridges constructed (from used oil-drilling pipe and cable) by Walter Yánez. 


If a village wants a bridge, they can write to the provincial government. A vehicular bridge is preferred, but if that's not possible, Walter will come and perform a survey with an EDM and hand level to see if he can build a footbridge.  


He gives the villagers instructions on where to dig the holes and returns in about a month to pour the foundations and anchorages for the bridge. Then he'll return with the pipe and cable and work with the village to construct a suspension bridge up to 100 meters in length.


We'll take a closer look at Walter's bridge tomorrow.

Ecuador's Bridges: Puente Rio Baba (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.