Chilean Bridges: Vespucio Norte POC

Speaking of earthquakes, we saw a few pedestrian overcrossings (POCs) that had collapsed during the February 27th earthquake in Chile. The superstructures were attached to the piers with two 5/8" rods that broke during the shaking.

This damage to the POC that went across the Vespucio Norte Expressway (the ring road around Santiago) was fairly typical. Of course, once it fell, it closed traffic on the expressway below (and was a hazard) until it was moved. Luckily the earthquake occurred at 3 AM.

Stronger connections between the girders and the piers and a global analysis to account for the complicated behavior of POCs when they are shaken should be routinely done to protect pedestrians and the traffic below POCs.

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

Chilean Bridges: Concepcion POC with Spiral Ramps

Just a couple more pedestrian overcrossings (POC) and then we'll move on to something else.

I like the spiral ramps on this POC, although I'm surprised there is sufficient headroom for an adult. I noticed that they also provide a regular sloping ramp on one side of the road. Maybe they didn't have room to provide a sloping ramp on the other side? I also wonder if the columns for the spiral ramps are hollow and if they have a roof?

I remember there was a POC with spiral ramps near the beach in Santa Monica that was closed because of concerns how it would perform during an earthquake. However, this POC seems to be a more modest structure and the central column probably provides more stability.

Chilean Bridges: Concepcion POC w/ Spiral Ramps by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

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: Pasarela Plaza Del Trebol

Another footbridge, this one carrying people from the mall over Talcahuana Way to a bus stop. I guess this structure can best be described as utilitarian. It certainly gets a lot of use.

We went to the food court in the mall for lunch. It had a huge dining area, and it was packed on a Wednesday afternoon. While we were eating, a big aftershock started shaking the mall. All the talking stopped and you could hear a pin drop. It looked like the crowd was ready to panic, but thankfully the shaking gradually subsided.

This bridge is a kind of tubular truss structure supported on four-legged towers, and enclosed in translucent plastic. This type of structure has become very popular lately and it has an interesting appearance although I don't think of it as structurally significant.

Pedestrian Overcrossings are vary common throughout Chile and are a good away of keeping people and automobiles away from each other.

Chilean Bridges: Pasarela Plaza Del Trebol by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Chilean Bridges: Pasarela Peatonal sobre la Autopista Alessandri

Another pedestrian overcrossing in Concepcion, Chile. It is just northwest of Puente Juan Pablo II over the Rio Bio Bio.

This is a simple Warren through truss with a arched top chord. It looks like a pony truss, which means that it doesn't have a portal frame or any cross bracing on the top.

Chilean Bridges: Pasarela Peatonal sobre la Autopista Alessandri by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Great Britain: Poplar Station Walkway

In this photo I'm standing at the north end of Canary Wharf looking toward the ancient hamlet of Poplar. The steeple of the early 19th century All Saints Poplar church can be seen in the background.

This bridge reminds me of one of The Happy Pontist's 'copycat coils.' It's a high level walkway to a light rail station over a highway.  There are a variety of elements (white staircases, a grey tower with cable-stays, a greenish tube) that don't seem to be very happy together.

Note the ornate ramp and bridge (in shadow) on the left side of the photo and the neo-Georgean buildings. This mixture of styles (similar to the different elements on the bridge) are hard on the eyes. Perhaps the walkway will get along better with it's neighbors over time, but its hard for me to imaging it being around that long.

Great Britain: Poplar Station Walkway 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.

Mexico's Bridges: Nuevo Caxitlan POC

The road from Manzanillo to Colima includes many pedestrian overcrossings (POCs) that carry people (and especially children) over the busy highway.

The Nuevo Caxitlan POC connects the town of Nuevo Caxitlan to an orchard (and farmer's markets) to the south. With its metal roof and railing, it makes a pleasant place to stand and watch the passing traffic. Apparently, it also makes a convenient place to mount advertisements and political posters.

This POC includes two spans over the highway and long zigzagging ramps along the sides of the highway. Note that the spans over the highway are made out of two precast girders laid side by side. Also note that the bent cap has big shear keys.

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