Sunday, December 17, 2017

Bridges of Mexico: Highway 438D Overcrossing near Santiago Atzitzihuacán

September 2017 (18.8268, -98.6038) Highway 438D Overcrossing
Driving west out of Puebla on Highway 438D we came upon an overcrossing near Santiago Atzitz Huacan. It's a 3 span precast girder bridge on tall single column bents. The bents are located in deep cuts on the highway shoulders. This is because the highway itself is deeply cut into the surrounding hills. The engineers must have carefully calculated the volume of cuts and fills needed to built this road.  Note the vegetation growing in the expansion joints between the spans. All of the rain and debris caught in the joints must make a fertile environment for any seeds that find a home there.
This seems to me like a very common type of bridge in Mexico, perhaps as a result of having to build highways through the many mountain ranges. I saw much taller bridges during a previous trip through Colima, Mexico. Note that part of the cut around the south bent has sloughed off, probably as a result of the September 19th earthquake. However, no damage or even signs of movement were seen on the columns or on the simply supported spans. 

In the photo below we can see they are excavating to make the roadway wider. I wonder if they will also have to lengthen the bridge to span wider shoulders or additional lanes?
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