Peru's Bridges: Puente Los Banos

In the interest of completeness, I thought I would include a bridge across el Rio Sama, one of the southernmost rivers in Peru. 

Unfortunately this photo was of a bridge that had been damaged during the 2001 earthquake. My notes say, "This is a three-span continuous RC box girder bridge supported on two-column bents and seat-type abutments. There were several structural details that made this bridge particularly vulnerable to shaking.  The lack of a wingwall behind the abutments allowed the embankment material to move away reducing the stiffness and damping of the bridge. The tops of the abutments were pushed back by the superstructure exposing the piles.  Because the abutments had lost their stiffness, the earthquake demand had to be taken by the two-column bents.  However, the bents had no top cap and so there was no frame action between the columns to stiffen them.  As a result, there was damage to the abutments and bents.  The soil at this location was also a problem, being very loose and unconsolidated.  During the earthquake, the soil on the south-side of the bridge laterally spread toward the river, breaking a quaywall."

As can be seen in the photo, vehicles were fording the Sama River while the bridge was being repaired. 

Peru's Bridges: Puente Los Banos by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Peru's Bridges: Puente Locumba

We've looked at bridges across several of the major rivers in Peru. Moving to the south we've crossed the Rio Camana, Rio Sihaus, Rio Chili, Rio Tambo, Rio Moquegua, Rio Locumba, and Rio Sama.

All these rivers flow out of the Andes and across parched desert on their way to the Pacific. When I was there in 2001, there was talk of damming these rivers and turning the desert into a breadbasket like in California. Hopefully, they won't be stealing water from the campesinos in the process. When this was done in California, the poor farmers in the Owens valley tried to stop them without success. At least according to the movie Chinatown.

I'm skipping several bridges on Tambo and Moquegua in order to look at a bridge on the Rio Locumba. Puente Locumba is a two-span continuous, haunched T girder reinforced concrete bridge on a pier wall and seat-type abutments. The deck is about 100 feet long by 30 feet wide and is supported on four girders.  Gabions are strung along the sides of the river for erosion control.

During the earthquake, the superstructure moved back and forth, damaging the abutments and the soil behind the abutments dropping the approaches several feet There were several optical cables on the bridge that were also damaged.

When we were at the bridge site about a month after the earthquake, a drilling rig was sitting on the north embankment suggesting that soil testing was being completed before repairs were made. Note the temporary bridge behind Puente Locumba consisted of gravel poured into the river as a driving surface with a culvert at the center to allow the water to flow.

I find this two span continuous bridge to be a very attractive solution when a river is too long to be spanned by a single span. The bridge is like a children's teeter-totter, balanced securely between the two abutments. I also like the green superstructure and striped barrier rail. To me this is a quintessential Peruvian bridge, elegant, simple, and attractive.

Peru's Bridges: Puente Locumba by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Peru's Bridges: Puente Freyne (2)

A view in the opposite direction (toward the northwest) at Puente Freyne and the Tambo River. We are about six miles from the Pacific Ocean. You can see in Google Earth (below) that the river bends back and forth around sandbars  between straight, artificial banks, probably for flood control.

The roadway runs along the coast and then goes inland for several miles before crossing the river and turning back to the coast. Perhaps this is to provide transportation to the farms along the river. In Google Earth (below) you can see a weir just downstream of the bridge and irrigation canals to water the crops in the valley. Peru has plans to dam it's rivers in the mountains and turn it's deserts into farmland.

Puente Freyne is a three span, 400 ft long deck truss supported on hammerhead piers and seat-type abutments. The bridge abutments are tall in order to support the deep truss while still providing a roadway at deck level.  The piers sit in the river suggesting that cofferdams were used or perhaps the river was diverted during construction of each pier.

This truss bridge is different from Puente Montalvo in many ways. In Puente Montalvo the truss had posts between the 'downward-pointing' triangles while this bridge has posts between the 'upward-pointing' triangles. Puente Freyne is a deck truss while Puente Montalvo is a through truss. Also, this truss is old and rusty while the truss for Puente Montalvo is new and freshly painted.

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

Peru's Bridges: Puente Freyne (1)

Traveling south from Arequipa, we occasionally would cross a green river valley in the otherwise incredibly dry Sechura Desert. Traveling on the Pan-American Highway we crossed Rio Tamba, Rio Moquegua (across Puente Montalvo), Rio Locumbo, and Rio Sama before arriving at Tacna, a border town with a huge public market selling bootleg CDs and DVDs (along with legitimate goods).

Typically, Peruvian bridges are elegant structures. However, Puente Freyne across Rio Tamba (on coastal highway 15A) looks like an old dinosaur with new legs.

Probably the highway department bought an old railroad bridge, moved it to the site, and jacked it onto new reinforced concrete piers. The three span truss superstructure (perhaps six meters deep) looks too big for highway vehicles and for the short, modern piers.

Perhaps that's the reason the bent cap suffered shear damage and one of the bearings fell over during the 2003 Atico, Peru earthquake. The bridge was closed when we got to the site while the crew went about repairing the pier and jacking the truss superstructure back in place.

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

Peru's Bridges: Puente Miguel Grau (2)

A view of an arch span and the approach structure on the east side of Puente Miguel Grau.

The stone walls have buttresses to hold back the soil that supports the roadway. Note the handsome balustrade (supporting lampposts) at the top of the wall and a gated stairway near the end of the structure.

The sidewalk widens on the east side, allowing people to congregate. The west approach has a traffic circle and a statue of Miguel Grau.

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

Peru's Bridges: Puente Miguel Grau (1)

A photo of Puente Miguel Grau across La Marina Blvd and Rio Chili. I'm not sure why a bridge named after Admiral Grau (a Chilean who fought a war against Peru) is in Arequipa. Perhaps he is respected for his courage.


The bridge is a closed spandrel, stone masonry, multiple span arch in the 'Centro Historico' part of Arequipa.  I think the handsome arches are done a disservice by the water main hanging from the parapet. Unlike the lacy railing on Puente Bolognesi, this bridge has a stone railing along the edge of the deck. 


Note that the bridge was constructed in a similar manner to the ancient Roman bridges. A stone pier supports a cut stone arch with bossed facing stones. Bridge construction began in 1884 and was completed in 1898. It has quite a bit of damage: some the result of earthquakes, but most the result of its age. We'll take a closer look at this interesting structure tomorrow.

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

Peru's Bridges: Puente Francisco Bolognesi (2)

A slightly out-of-focus photo of Puente Francesco Bolognesi over the Rio Chili. One of the volcanos that surround Arequipa (probably Nevado Chachani) can be seen through the arch on the left.  The volcano is 6100 meters tall and towers over Arequipa which is at 2200 meters above sea level.

Rio Chili looks like a fast-moving whitewater river in this photo. The river and the mountains make Arequipa a popular tourist destination for young people who enjoy the outdoors.

Peru is a very pretty country with many people dressed in embroidered jackets and tiny hats, with a mixture of Spanish colonial and Incan architecture, and an abundance of llamas.

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

Peru's Bridges: Puente Francisco Bolognesi (1)

Eventually, we arrived in the lovely city of Arequipa, which is home to a variety of old and new bridges.

Puente Francisco Bolognesi is an old stone masonry closed spandrel arch bridge. It consists of five spans over the busy La Marina Blvd and Rio Chili.

This bridge resembles the Puente de Toledo in Madrid with its round turrets between the arches. However, the Puente Francisco Bolognesi has a delicate iron railing instead of a heavy stone parapet along the edge of the deck.

Puente Bolognesi is the oldest bridge in Arequipa. Construction began in 1577 by the architect Juan de Aldana and it was completed in 1608 at a cost of 150,000 pesos.

Peru's Bridges: Puente Francisco Bolognesi (1) by Mark Yashinsky is licensed under a Creative Commons Attribution 3.0 United States License.

Peru's Bridges: Puente Rio Camana

Continuing on Highway 18 towards the Pacific (16° 35.14'S, 72° 43.87'W) we come upon a four span continuous, reinforced concrete box girder bridge on pier walls and seat-type abutments. The soffit rests on steel bearings at the abutments but appears to sit directly on the piers. Perhaps there is a thin steel plate between the soffit and the top of the piers since this long bridge must expand and contract with changes in temperature.

The pier walls have a hexagonal shape that provides cutwaters to deflect debris and reduce dynamic fluid forces on the piers. The piers are attractively tapered below the soffit. The superstructure has vertical sides and supports a streamlined barrier rail.

The concrete is almost the same color as the ground and the surrounding mountains and blends in well with the environment. The bridge seems to be in good shape and appears to have been carefully designed to be an attractive and efficient structure.

At least from the two highway bridges we've seen so far, it appears that Peru has embraced a 'modern' aesthetic for it's highway structures with clean lines and neutral colors.

Peru's Bridges: Puente Rio Camana by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States Licens

Peru's Bridges: Puente Rio Sihuas (2)

One last look at the Puente Rio Sihuas. I did a little investigating to determine what kind of truss this is. The always reliable Bridgehunter shows a similar bridge in Wyoming (the New Fork River Bridge), which he calls a Kingpost pony truss. However, that bridge had only a single floor beam at midspan while this bridge has a floor beam under every vertical member. I wonder if that makes a difference?

I've been talking about how bridges can be used to improve the lives of poor people in Ecuador. I wonder if the lives of poor people in Peru are improved by the Pan-American Highway?

In both Ecuador and Peru, there has been conflict between the mestizos (mixed European and native) and the indigena (native) populations. For a while, there was a war between Shining Path guerrillas and the government of Peru. I saw a documentary on PBS about the Institute for Liberty and Democracy (ILD) that caused a real revolution in the lives of poor people in Peru by giving legal rights (especially for land ownership) to farmers who didn't own the land they lived and worked on.

There's a nice movie, The Motorcycle Diaries (Diarios de motocicleta) about a young Che Guevara taking a motorcycle trip across Latin America and discovering the poverty of the indigena. My feeling is that providing legal rights, sources of capital, and more transportation alternatives (bridges) for poor people may do more to lift them out of poverty than armed revolution.

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

Peru's Bridges: Puente Rio Sihuas (1)

I thought we might continue south from Ecuador and look at some bridges in Peru. I was there a few years ago to look at bridge damage after one of the large earthquakes that occurred along the Pacific Coast. Peru is an interesting country with extremely tall mountains, a very dry desert (to the west), and the Amazonian River Basin (to the east).

Puente Rio Sihuas is on Highway 18 (the Pan-American Highway) between Arequipa and Camana at latitude16° 20.70’ S and longitude 72° 07.95’ W (we crossed the equator while looking at Walter's bridges in Ecuador).

Puente Rio Sihuas is another pony truss bridge. It has three simple steel through truss spans on pier walls and seat type abutments The superstructure is supported on tall, steel bearings.

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