Chilean Bridges: Pan American Highway POC

There are so many concerns besides load carrying capacity when designing a pedestrian bridge. If the structure goes over a highway, you have to wrap the pedestrians in a cocoon of wire mesh to protect the drivers below. I think these fences are aesthetically displeasing and they seldom work well with the structure.

This tied arch over the Pan American Highway includes a tunnel of fencing, which does a good job of protecting drivers but it stick out unpleasantly past the arch. I suppose it's possible to make the fencing work with the arch, but I've never seen a satisfactory solution.

Chilean Bridges: Pan American Highway POC by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Chilean Bridges: Puente Ferroviario de Lontué

Another railroad bridge viewed from the side of Route 5 Sur in Chile. The railroad bridge (along with the adjacent highway bridges) was damaged by flooding of the Rio Lontué in 2008, effectively dividing the country in two. The railroad bridge looks the same so they must have been able to pick it up and set it back on it's piers.

Charles Darwin also writes about the Rio Lontué in his journals and speculates that an earthquake in 1762 caused a landslide and dam across the Rio Lontue. The water eventually burst through spreading boulders throughout the area. This may be the first description of debris dams that continue to cause damage following earthquakes. He further speculates that such debris can now be found atop mountains suggesting that parts of Chile have been uplifted over time.

The Puente Ferroviario de Lontué is a three span through truss. The end spans have a curved top chord while the center span has a straight top chord, which seems to be a common arrangement.

Chilean Bridges: Puente Ferroviario de Lontué by Mark Yashinsky is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

Chilean Bridges: Viaducto del Malleco

The Malleco Viaduct was the tallest railroad bridge in Chile when it opened in 1890. It runs parallel to the PanAmerican Highway (Route 5) in South-Central Chile. Apparently Gustave Eiffel made a proposal to design the bridge, but his proposal was rejected and the design went to Aurilio Lasterria.  It's an interesting lattice truss with fillets connecting the superstructure to the towers.

The railroad runs parallel to the highway for much of the length of Chile. Note that the train is powered by a cable suspended above the tracks. It would seem that the railroad would be an ideal transportation solution for a long, skinny country like Chile, but it is barely used (similar to the US). After the earthquake, the railroad was utilized to remove building debris.

Chilean Bridges: Viaduct Malleco by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.