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 Pampa Blanca over the Tambo River

Puente Pampa Blanca (White Prairie Bridge) is a two span though truss on two column bents and seat-type abutments. Each span is 150 ft long and 30 ft wide. The bridge crosses the Rio Tambo about five miles north of Puente Freyne. It carries Route 18, which goes north, crosses the river, and then turns northeast along the east side of this fertile valley (see Google Map).

Using the language we've adopted from The Happy Pontist, this truss only has posts in the 'upward-pointing' triangles. In this photo you can see the floor beams supporting the deck at the bottom of each post and at the point of every 'downward-pointing' triangle. I believe the Happy Pontist explained that the additional posts we often see are there to provide lateral stability to the frame and are not needed when ample cross-bracing is provided to support the compression chord.

We've just looked at three Warren truss bridges. Puente Montalvo is a through truss with posts only in the 'upward-pointing' triangles. Puente Freyne is a deck truss with posts only in the 'downward-pointing' triangles. Puente Pampa Blanca is a through truss with posts only in the 'upward-pointing' triangles. This suggests that when the deck is at the bottom of the truss the vertical tension members are supported by 'upward-pointing' triangles. When the deck is at the top of the truss the vertical compression members are supported by 'downward-pointing' triangles.

In the photo above, we can see that Puente Pampa Blanca was being completed when we visited the site in 2001. If I recall correctly, the only damage from the earthquake was to some steel bearings. I'm not sure why, but I don't find this bridge to be as elegant as Puente Freyne or Puente Rio Sihuas. Perhaps it's just the red paint.

Among the many excellent tools provided by Google (besides this easy-to-use blogging program) is an automatic Spanish to English translator that I've used for the many articles I've read on the bridges of Peru. Of course it's not perfect. Anyway, here is what an article said about the opening of the bridge after Google translated it.

Pampa Blanca Bridge integrated into development. In an emotional popular act was attended by the Minister of Transport and Communications Engineer Luis Chang Reyes, l 29, was inaugurated last September Pampa White Bridge in distritro Cocachacra, an old dream coming true of the whole Province.

Bridge construction Pampa Blanca, whose cost exceeds five million suns, has been executed pursuant to an agreement signed between the private sector represented by the companies Terminal Internacional del Sur Tisure S. A. Central and S. Sugar Chucarapi A. whose combined economic contribution to the contributions of the Provincial Municipality of Islay Municpalidad Deistrital of Cochchacra and Ministry of Transport and Communications have made this work possible, as a clear indication that by entering into with private companies can accelerate the pace of our development.

Hopefully, some slight meaning has been retained. The bridge was made possible by funds provided by local governments and agricultural industries in the area. This ensured that their products could be quickly shipped to world markets. Note the green fertile valley that surround the river and the dry white cliffs on the edges of the satellite photo below.

Peru's Bridges: Puente Pampa Blanca 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 Montalvo sobre el Rio Moquegua

After leaving beautiful Arequipa we drove south on the Pan-American Highway (across deserts and mountains) to the verdant river valley of Rio Moquegua and our next bridge.

It took a while to identify this bridge because the sign in front made me worry the bridge name began with 'CA.'  However, everything in the photo was in the Google Earth view of Puente Montalvo (see map below). Also I was able to follow my photos from Arequipa to Ilo and this was one of the few river valleys that was crossed between the two cities.

Puente Montalvo is an interesting single span, two lane, through truss bridge. It is another odd truss bridge, which apparently delights Peruvian engineers. There is a big compression chord on top and seven tall triangular frames, each with a vertical post that holds up a floor beam and the bridge deck. However, there are no posts between the triangular frames. I found a similar bridge (built in 1871) in the Model Railroader's Guide to Bridges, Trestles, and Tunnels. These are some of the best books on old bridges because of their compulsion to realism in their models.

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

Peru's Bridges: Culvert, Tunnel, or Bridge?

A low-resolution photo taken while leaving Arequipa. But what are we looking at?

We've often discussed whether it's cheaper to build a long trestle structure or a long embankment. Its amazing that an embankment with such steep sides (as shown in the photo) can support a roadway.

I was looking at the book Bridges, Canals, & Tunnels. They showed a 450 ft long timber trestle railroad bridge near Promontory Point, Utah.  It was so flimsy that they covered it with earth after it was built. However, I don't think this embankment has a timber structure underneath.

So is this structure a culvert, a tunnel, or a bridge? I would argue that it is a single span, filled spandrel arch bridge built to allow a grade separation between two highways.

Peru's Bridges: Culvert, Tunnel, or Bridge? by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Peru's Bridges: La Marina Blvd POC

A pretty pedestrian overcrossing (POC) across La Marina Blvd in Arequipa, Peru.

Three reinforced concrete hammerhead bents support two simple-span through-girder superstructures. Small shear keys keep the superstructure from moving transversely. There's a steel stairway at each end to get people on and off the structure.

I like the use of yellow and green paint to give the structure an Art Deco appearance. In the U.S. we seldom paint a concrete structure because of the increased maintenance costs. Maybe the cost of labor is smaller in Peru.

This POC takes pedestrians across a busy street to the east bank of the Rio Chili, which seems like an odd destination (see Google Earth Map). Perhaps its to take kayakers and fishermen safely to the river?

Peru's Bridges: La Marina Blvd POC by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Peru's Bridges: Puente Rio Chili

Its always interesting to study a new bridge. The Puente Rio Chili in Arequipa is a single span reinforced concrete box girder bridge with end-diaphragm abutments; basically a rigid frame. Note how the far abutment is only half covered in cobbles and has no wingwalls (it looks like they are about to be built) while the closer abutment is covered in sand and gravel with wingwalls extending along it's sides. Probably they were just completing the far abutment. There's a notch in the deck/backwall of the near abutment for an approach slab or roadway.

The bridge is about 200 ft long and 60 ft wide; a four lane bridge with a short median barrier cast in the middle and steel guardrails along the deck overhangs. Even at $50 per square foot, this bridge would have cost over half a million U. S. dollars. It looks like a modern highway bridge, but it doesn't connect to a major road or highway. There are just some farms and what looks like storage facilities on the other side of the river. It seems like a very expensive bridge just to be used by a farmer to bring his crops to market.

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

Peru's Bridges: Puente Bajo Grau (2)

Here is another view (looking to the south) of Puente Bajo Grau. The haunch looks much bigger on the right side of the bridge. I wonder if there's a moment connection on the west side and its free to move on the east side?

I guess I didn't take this photo since I'm standing with my earthquake buddy Bill Byers in the picture. Bill was the chief bridge engineer of the Burlington Northern Railroad for many years, he was quite active, and helped develop the seismic criteria for AREMA, the railway engineering manual.

Puente Bajo Grau crosses the Rio Chili at a large skew as the road goes to the northwest and forms a triangle with La Marina Blvd and Ejercito Avenue (see Google Earth Map below).

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

Peru's Bridges: Puente Bajo Grau (1)

I'm standing on La Marina Blvd. looking north at Puente Bajo Grau, Puente Miguel Grau, and the Nevado Chachani Volcano. The statue of Miguel Grau can be seen just above Puente Bajo Grau's west abutment.

Puente Bajo Grau is another single span, reinforced concrete, haunched girder bridge. It's also another bridge with a water main along the exterior girder. The bridge has end diaphragm abutments, short wingwalls, and steel rails.

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

Peru's Bridges: Puente San Martin

Between Puente Bolivar and Puente Quinones is Puente San Martin. I decided to show this bridge, not because it is particularly interesting, but because two of the volcanoes that surround Arequipa are in the photo.

On the right is Volcan Misti with a conical shape as fine as Mt. Fuji. On the left is the Nevado Chachani Volcano with a complicated structure that includes several domes. Both volcanoes are about 6000 meters tall. Neither have erupted in a long time, but both are considered active.

San Martin is a single span, reinforced concrete, haunched girder bridge carrying two lanes of traffic. If you look closely, you can see a water main being carried along the exterior girder, which ruins the appearance of the haunched girder.

Jose de San Martin was an Argentine general who helped liberate (along with Simon Bolivar) South America from Spain. San Martin Road goes east from Freedom of Expression Park (Parque Libertad de Expresion) across the Rio Chili, across La Marina Blvd, around Martinez Circle (Ovalo Martinez), to the Southern Institute (Instituto del Sur). Arequipa is called the 'White City' because of all the white rock that has been quarried from the surrounding mountains for churches and government buildings.

The Rio Chili is crossed by a variety of interesting bridges from it's source in the Cordillera Occidental Mountain Range until it empties into the Pacific at the Valle de Quilca. Unfortunately, I've only photographed a few bridges in the city. Perhaps one day, I can make a survey of all the interesting bridges in Peru or at least, all the bridges that cross the Rio Chili.

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

Peru's Bridges: Puente Quinones and Puente Consuelo (2)

A look at the west abutment and west retaining walls for Puente Quinones and Puente Consuelo (along the Rio Chili). Note how this structure is much more detailed than most bridges or even buildings. The retaining wall is locked into the rock like a dam and has folds and ridges that must have taken a lot of work to form.

A pedestrian overcrossing (POC) was built over Abelardo Quinones Street. The retaining walls reach up to support the blue, open, four sided structure.

I guess I find this bridge to be overly elaborate. I prefer the structural simplicity of Puente Bolivar. Still, it's an interesting experiment, and better than a lot of unimaginatively-designed bridges.

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

Peru's Bridges: Puente Quinones and Puente Consuelo (1)

After spending a week looking at older bridges, we'll look at a few newer bridges before leaving Arequipa.

Puente Quinones and Puente Consuelo are a  pair of bridges that connect Abelardo Quinones to Consuelo Streets across the Rio Chili with ramps on and off La Marina Blvd.

The bridges were being completed when I took this photo. It's interesting how highly contoured the soffit is on these bridges. In this photo (looking south at La Marina Blvd) instead of a typical column flare, the soffit dips to take the shape of the column. The bridges remind me of sculptures by Naum Gabo. Just another sign of Arequipa's affinity for all things modern.

I'm surprised by the low vertical clearance of these bridges. I would imagine they would be hit by trucks carrying equipment, unless the city has an effective way of screening traffic onto La Marina Blvd.

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

Peru's Bridges: Puente Bolivar (4)

One last photo of Puente Bolivar. There's something strange about such a long viaduct that carries only a single lane of traffic. It's as if each car was a tiny train on its long trip above the valley floor.

Perhaps the City of Arequipa just needed an excuse to keep the bridge in service. There are alternative routes half a mile to the north and south. Also, there are wide sidewalks on both sides of the deck, so the bridge's main purpose may be as a pedestrian overcrossing.

I was looking through the blogs and websites for information about Puente Bolivar and I found a comment from a Peruvian that Gustave Eiffel hadn't really designed this bridge. According to the writer, an architect had done some research and it was just a myth!

Based on its appearance, I find it hard to say whether Puente Bolivar is the work of Gustave Eiffel. Ponte Maria Pia and the Garabit Viaduct are magnificent structures that look like the Eiffel Tower turned into bridges (see David Billington's The Tower and The Bridge). They don't seem to have anything in common with this rather plain structure. Ponte Internationale and the Rouzat Viaduct have interesting superstructures rather than the rather plain triangular truss elements on Puente Bolivar. Still, there is something evocative of Eiffel in this structure. I just don't think it's one of his major works.

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

Peru's Bridges: Puente Bolivar (3)

Another view of Gustave Eiffel's Puente Bolivar (Puente de Fierro). This bridge was built out of little more than small angles, rods, and plates. It was designed by Eiffel and the plans and parts were sent from Europe to be assembled at the site. It's hard to imagine that this delicate structure ever supported a steam locomotive.

The towers are bolted to stone masonry piers. Diagonal elements provide lateral stability to the four tower legs. Floor beams are at each vertical member and support a concrete deck. I like the lace-like railing on the deck. I wonder if it was part of the original structure or if it was added later?

It seems strange to have such a long viaduct just to cross the Rio Chili. Perhaps it was economical to build a 500 meter long viaduct so that the track could maintain it's grade across the valley. In the map below, we can see to the east of the bridge an railroad yard and train station whose tracks used to go onto the bridge.

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

Peru's Bridges: Puente Bolivar (2)

Another view of Gustave Eiffel's Bolivar Bridge, popularly known as Puente de Fierro (the Iron Bridge).

I like the pretty neighborhoods that the viaduct goes through with their mix of  Spanish colonial and flat-roof modern homes. The modernist (mid 20th century) style must have made quite an impression on Peruvians.

I wonder though what it's like to have a viaduct in front of your house?

I noticed that some of the squares under the towers have been turned into flower gardens. That they maintain and continue to use this 120 year old structure suggests that the people in Arequipa are proud to have a bridge designed by Eiffel in their city.

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

Peru's Bridges: Puente Bolivar (1)

Another old bridge in Arequipa, which was designed by Gustave Eiffel in 1882. Although it's nice, it is not one of his more beautiful structures.

Puente Bolivar is a 488 meter long iron viaduct. Most of the viaduct is composed of four legged towers with little deck truss spans between the towers. A long span over the Rio Chili looks very much like a Fink truss, which was designed by Albert Fink of Germany in the 1860's according to the excellent Wikipedia entry on truss bridges.

In this type of truss, we can see diagonal tension members being used to support vertical elements at the eighth points of the span. I like how we can clearly see the forces being carried on this type of truss.

At the time it was built, I believe this bridge was used to carry a  railroad on it's way to Cuzco. Now its used to carry a single lane of vehicles west into the city. We'll take another look at this interesting structure tomorrow.

Peru's Bridges: Puente Bolivar (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.