Mexico's Bridges: Puente Cuatro Caminos (2)

This bridge is near the intersection of roads going to Tuxpan, Ciudad Guzman, Tecalitlan, and Colima, hence the name Cuatro Caminos.

Puente Cuatro Caminos has three precast I-girder spans and short slab end spans. I wonder why they needed the little end spans?

It looks like the girders and the deck are simple spans, but they covered the deck (including the expansion joints) with asphalt so the bridge looks continuous from the road.

The I-girders are supported by large two column bents. Note that the top of the bents have wide platforms, perhaps for jacking up the spans and replacing the bearings.

Route 54D continues another 80 miles to Guadalajara, but I turned around at this point and returned to Colima.

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

Mexico's Bridges: Puente Cuatro Caminos (1)

I've often observed that a bridge is almost unnoticeable from the roadway above. Someone driving on Route 54D towards Guadalajara might not be aware that they had driven over a canyon unless they had taken their eyes off the road.

Puente Cuatro Caminos (the Four Roads Bridge) is a tall precast girder bridge on a sharp radius horizontal curve. We'll take a closer look at this bridge tomorrow.

Mexico's Bridges: Puente Cuatro Caminos (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

Mexico's Bridges: Puente Atenquique I (5)

One last look at Puente Atenquique I, the very active Volcán de Colima, and the older, taller, and inactive Nevado de Colima.

This is a very beautiful area. A cloud forest (Sierra de Manantlan) with an abundance of the world's flora and fauna is nearby. There are many quaint villages with cobblestone streets around ancient churches. And there are modern two-lane highways with 250 ft tall, incrementally launched bridges.

Mexico's Bridges: Puente Atenquique 1 (5) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Mexico's Bridges: Puente Atenquique I (4)

Another view of Puente Atenquique with the inactive Nevado de Colima in the background. More information on this volcano and the highly active Vulcon de Fuego de Colima is available on Wikipedia.

Bridge engineers now have a variety of construction tools for building long, tall structures.

Bridges can have both segmentally constructed substructures and superstructures. They can use prefabricated girders or the girders can be cast-in-place using advancing forms. Suspension bridges, cable-stayed bridges, and long prestressed girder bridges can all be built segmentally. Truss bridges can also be built segmentally, although fewer are being built today. Incrementally launched bridges can also use precast or cast-in-place segments.

I wonder if it's possible to build an incrementally launched arch bridge?

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

Mexico's Bridges: Puente Atenquique I (3)

Another incrementally-launched post-tensioned box girder bridge built in 1989 by Mexpresa on Route 54D in Colima Mexico.

The bridge seems to be in pretty good shape, although I wonder why those tendons/rebars are sticking out of the side of the box?

I imagine that the columns were segmentally constructed. A certain length of column forms were put together, the concrete is poured and cured, and then the forms were raised and additional concrete poured above the cold joint. This process was repeated until the column was completed.

I wonder if the entire rebar cage is first assembled.  It may be difficult to assemble and support a 250 ft tall rebar cage while the concrete is poured, but it's certainly possible.

The box girder superstructure was assembled just like the superstructure on Puente Atenquique II. The concrete was poured in units between a quarter to a half of the span length and then pushed out from the abutment. A steel nose was attached at the end to provide support from the next pier. The hydraulic jack must be well anchored to be able to push a bridge all the way to the other abutment. I think the development of hydraulic jacks has 'revolutionized' the art and practice of bridge engineering.

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

Mexico's Bridges: Puente Atenquique I (2)

This dramatic photo shows Puente Atenquique I just beyond an enormous road cut (and with two volcanos barely visible on the horizon).

I wonder how many days and how many tons of dynamite were require to remove all of that rock. It must have been quite a challenge to turn this rugged landscape into a well-graded highway.

Too often, we think of our bridges as something separate or more important than the roadway or railway that are the main purpose of all the money, effort, and occasional loss of life that are required to improve the lives of people.

 I think roads are essentially benign. Clean drinking water requires roads for water trucks, drilling rigs, steel pipe, pumps, etc. The right-of-way along a road carries waterlines, electric lines, communication lines, etc.  However, I agree with Norrin who mentioned that highways without sidewalks are too dangerous for people traveling by bike or on foot. Perhaps a good transportation system includes a mix of footpaths, horsepaths, bike paths, roads, and rails so that no one has to risk their life when they chose to travel.

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

Mexico's Bridges: Puente Atenquique I (1)

Rio Atenquique is quite meandering, and so about a mile north of the Puente Atenquique II it crosses under Puente Atenquique I.

I don't know why the sign for Puente Atenquique I shows a segmentally-constructed bridge with haunched girders. Most likely, the sign painter wasn't that knowledgeable about bridges. However, it's actually another incrementally-launched bridge like Puente Atenquique II. It only has seven spans though. It's a 320 m (1050 ft) long bridge, 75 m (246 ft) above the river, and with a 10.5 m (34.5 ft) wide deck.

Note the enormous road cut at back of this photo. Puente Atenquique is just beyond the cut. We have seen that the engineers who designed Route 54D always cut the top of the rise and then build a bridge over the subsequent valley. This makes the highway a little easier to drive, especially for someone (like me) who drives a Prius.

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

Mexico's Bridges: Puente Atenquique II (4)

A look at an abutment on Puente Atenquique II. I would guess that this is not the abutment from which the superstructure was launched, because the soffit looks like it rode over eight piers and the end looks like it carried the steel guide.

I would guess that the square blocks on the front of the abutment stem wall are decorative although its possible they could have supported some equipment while the bridge was being launched. The shear keys seem slightly ineffective since there's such a big space between the girder web and the keys. The long overhangs would be riding on the top of the keys before the box girder ever got near it. Still that might be sufficient to prevent the superstructure from moving very far transversely.

The back wall looks like it is right up against the superstructure which can't be right, unless this is an extremely warm day, which I'm pretty sure isn't true.

The superstructure is supported on special  bearings with a teflon or stainless steel top surface that allows the soffit to slide with a minimum of friction for the 1/4 mile over the piers. This type of bearing is specially designed for incrementally launched bridges. The nose attached to the end of the superstructure is long enough to prevent large cantilever moments when the span is hanging half-way between supports.

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

Mexico's Bridges: Puente Atenquique II (3)

Another view of Puente Atenquique II. It looks like a lubricant was applied to the bridge soffit to help the superstructure slide. There's also stains on the side of the superstructure, perhaps from the bridge launching system. You can see that the bridge is very straight, which must make launching the bridge easier (although I understand that bridges with horizontal curves are also built using incremental launching).

Mexico has many incrementally-launched bridges. The company Mexpresa has a website showing some of the incrementally-launched bridges they've built, beginning in 1978 with Puente Rio Tula in Hidalgo.

It looks like the pier closest to the viewer is somewhat stouter than the others, although I'm not sure why. Also, it appears that the bridge was built over a rock quarry. Note that the end of the bridge is at a road cut. The bridges must be at the top of grades and the cut material must be put at the bottom.

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Mexico's Bridges: Puente Atenquique II (2)

A closer look at the superstructure of Puente Atenquique II on Route 54D in Jalisco, Mexico.

I found this bridge referenced in Structurae. It was built in 1989, it has a 10.5 m (34.5 ft) wide deck, and it was build by incremental launching. We saw this technique used to build the Pont Charles de Gaulle in my blog of April 11, 2009. Although that was a steel bridge, the technique is similar. Box girder segments were cast behind the abutment, cured, and then pushed out with hydraulic jacks. It seems incredible to me that this 1/4 mile long bridge could be pushed out from one abutment!  It must have had a very high camber to have been cantilevered out so far without deflecting below the top of the pier!

A short article on incremental launching of bridges provided by the University of California at Berkeley is available on the Internet.  It looks as though a special nose is put on the end of the superstructure to help it get over the piers.

Note the squat bearings between the top of the piers and the bridge soffit. The superstructure must be able to slide on these bearings as it is pushed out across the canyon. Also note the rebar sticking out of the side of the superstructure. There must be a vertical diaphragm, perhaps at the end of each segment. I imagine each precast segment was pushed out and then post-tensioning tendons were attached to the next piece, which was also pushed out, until a completely post-tensioned superstructure reaches the other side of the canyon.

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

Mexico's Bridges: Puente Atenquique II (1)

I skipped past a single span bridge (Puente Los Hornos) and another space-truss structure (Puente El Nuevo) to arrive at the incrementally launched box girder bridge,  Puente Atenquique II. It has a continuous nine span superstructure on single column bents and seat-type abutments.

I looked up Atenquique and found that it is a town with a tragic history. Heavy rains in 1955 caused a flash flood that drowned many members of the community as they were attending Mass. It is also the name of the stream that runs under this structure.

The bridge is 83 m (272 ft) tall and 440 m  (1445 ft) long. Like the other continuous superstructure bridges spanning wide canyons on Route 54D, this structure is a single prestressed box girder with long, gull-wing overhangs. A 1445 ft continuous superstructure is extreme long not to have an intermediate expansion joint. The superstructure is supported on sliding bearings that allows it to expand and contract without flexing the very tall piers. The 17 inch thermal movement must be addressed by very large expansion joints at each abutment.

We'll take another look at this bridge tomorrow.

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

Mexico's Bridges: Puente Acatas

Another three-span precast girder bridge on two column bents and seat-type abutments. This bridge is very similar to the previously studied Puente Pialla.

Considerable effort was made to retain the slopes above the road and along the abutments. I like these handmade stone masonry retaining walls. The bridge seems more impersonal.

The deck looks like it is continuous across the three spans. The bridge crosses one of the many creeks (Acatas Creek?) running down the side of the volcanos.

Route 54D is near the base of these volcanos and runs parallel to a large river ( the previously encountered Armeria River?).

It looks like a road veers to the west away from the highway at the end of the bridge. There is a small gully a little west of the bride that drains this road into the creek.

This bridge also has asphalt spread onto the deck. This practice used to be common in California, and was sometimes done by road crews without asking the bridge engineer's opinion. It's even possible that there were expansion joints at the ends of the spans that were covered by the asphalt.

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

Mexico's Bridges: Puente Pialla (3)

A view of an abutment expansion joint at Puente Pialla, a segmentally constructed, two-span box girder bridge on Route 54D in Jalisco, Mexico.

The coefficient of thermal expansion for concrete is 0.000006 units per degree Fahrenheit. This bridge is 158 meters long but it has two expansion joints, so each joint only needs to handle expansion for half the structure. The maximum change in temperature is 100 degrees, so the maximum expansion is 0.05 m or about 2 inches.

This expansion joint looks like it can handle more than two inches of movement. It's made of three steel bars with rubber diaphragms that expand and contract as the bridge changes temperature.

Note that the steel railing is built to slide in and out of a larger diameter tube as the bridge expands and contracts.

The concrete barrier on each side of the expansion joint has been patched. Perhaps the barriers banged together during the 2003 earthquake. That is one of the most common types of earthquake damage.

The expansion joint looks to be in pretty good shape. I believe that the road/bridge crew has been doing a good job patching spalled concrete, keeping the expansion joint clean, and maintaining this bridge. Note that the material on each side of the joint is different than the asphalt father away from the joint. Perhaps the deck close to the joint is being kept free of asphalt? We've stopped putting asphalt on our bridge decks and we try to remove it from our decks whenever possible. There are much better materials currently available to protect bridge decks and that provide the deck with a longer life.

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

Mexico's Bridges: Puente Pialla (2)

I'm standing by the south abutment looking north along the side of the box girder superstructure of Puente Pialla on Route 54D in Jalisco Mexico.

From yesterday's photo we know that the road has two lanes of traffic and two narrow shoulders. It looks like the superstructure is just a single box girder with very wide overhangs. The superstructure with its haunched girders has an almost sculptural quality.

I can see some concrete patches, perhaps where there were rock pockets caused by problems vibrating the concrete during the pour.

We've been fortunate to get some good comments from Norrin who knows a lot about Mexican bridges. He said that these long bridges were built as balanced cantilevers, perhaps with some additional support during construction.

I imagine that after the concrete cured, the post-tensioning cables were jacked from both ends of the superstructure, set, and then the abutment backwalls were poured.

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

Mexico's Bridges: Puente Pialla (1)

Continuing north on Route 54D we come to a sign announcing we are about to cross the two-span Pialla Bridge. The Highway Department is justly proud of this large structure. The sign says the bridge is 158 m (520 ft) long and 89 m (292 ft) tall. It looks like another segmentally constructed cantilever structure, similar to Viaduct Beltran. We'll take a closer look at it tomorrow.

By the way, you may have noticed the steep cuts on the sides of the road, which are covered in wire mesh to protect motorists from falling rocks. My experience is that this mesh is quite effective for anything less than a large rockslide.

We are driving along the side of two large active volcanoes, and so the rock is probably cemented tuff or other pyroclastic material. Mexico's Pacific Coast is along a large subduction zone that causes many earthquakes and creates enough pressure underground to melt the underlying rock and cause active volcanoes.

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