Sunday, November 26, 2017

Bridges of Mexico: 150D/190 Interchange in the State of Puebla

September 2017 (19.2556, -98.98.0862) 150D/190 Interchange
Bridge engineers in the State of Puebla have a much larger toolbox than engineers in the State of California. For instance, I can count the number of cable-stayed bridges in California on the fingers of one hand but in Puebla, cable-stayed bridges are even used as connectors on interchanges.
In the Google Earth photo above a six span cable-stayed connector with three sets of towers is on our left (carrying traffic to downtown Puebla) while a seven span cable-stayed connector with only two sets of towers is on our right (carrying traffic to Perote and Veracruz).
These are unusual cable-stayed bridges. The connector carrying traffic to downtown Puebla has towers on the sides of the piers supporting the 1st and 2nd and the 5th and 6th spans. The 4th and fifth spans are supported by towers on a multicolumn bent in the median of Highway 150D (shown in the Google Earth photo above). Even more unusual is the connector carrying traffic to Veracruz, which only has two tower bents and so the 1st, 4th, and 7th spans are not supported by cables (see Google Earth photo below). Also, the connector shown below has two big outrigger bents supporting the center span. The connector shown above has a fancy sign with colored balls near the abutment.
A stunning feature of this interchange is that it sits on the flank of La Malinche, an enormous volcano. in fact, on a clear day you can see volcanos all around the interchange; part of the Trans-Mexican Volcano Belt. On the two days we spent in Puebla it was overcast but you can see La Malinche clearly in the first Google Earth photo and also at the top of the Google Earth photo below (the interchange is identified with a yellow pin). Puebla's elevation is over 7000 ft above sea level.
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Sunday, November 19, 2017

Bridges of Mexico: The Hermanos Serdán Blvd. Bicycle Viaduct in Puebla City

September 2017 (19.09170, -98.2296) Viaducto de Bicicleta de Puebla Ciudad
On September 24th I went with the Geotechnical Extreme Events Reconnaissance (GEER) Team to investigate the September 19th Mexico Earthquake. The group was mostly interested in looking at landslides and soil settlement but I did manage to photograph a few bridges.
Puebla is a modern city and a showcase for Mexican culture. Among its many attractions is an elevated viaduct for bicyclists (and pedestrians) in the median of Hermanos Serdan Blvd. This structure is 7.6 km long and just one of several bike paths in the city. The photos above show the elevated bicycle roundabout at Hermanos Serdan Blvd and Avenue Francisco Villa in Sanctorum.
What's particularly nice about the viaduct is the diversity of structures. The roundabout is a steel truss on steel truss piers but there are also cable-stayed structures (shown above), long stretches of steel stringers on oddly crossed steel piers (shown below), as well as arches (see bottom photo). The one unifying feature is that all the structures are steel and they're all painted white. 
In the next couple of months we'll look at new and old bridge structures in Puebla, Morales, and Mexico City that I photographed between stops to study earthquake damage. Interested readers can also see a similar set of photos that I took following the 2003 Colima, Mexico Earthquake.
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Sunday, November 12, 2017

Mendocino County, California Bridges: Highway 1 Bridge across Ten Mile River

September 2017 (39.54917-123.76278) Ten Mile River Bridge
Ten Mile River Bridge (10 0274) is an eight span prestressed concrete box girder bridge that was built in 2009. It replaced a timber deck truss bridge that had been built at this site in 1954 (see photo below, courtesy of the Mendocino County Historical Society).
With the tight radius curve at the south end of the bridge along with it's streamlined appearance and the dramatic landscape of water, sky, and rugged hills, this bridge provides some visual excitement. Note the open barrier rail and sidewalk, which is appropriate for a bridge along the coast.
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Sunday, November 5, 2017

Mendocino County, California Bridges: Highway and Railway Bridges across Pudding Creek

September 2017 (39.4586, -123.8078) Pudding Creek Bridges
A highway bridge and a railway bridge (now converted to a pedestrian bridge) cross Pudding Creek a few hundred yards from each other. The Highway 1 Bridge (10 0158) is an eight span, precast concrete channel beam bridge that was built in 1959. The bridge was seismically retrofit in 1996. Large diameter piles were placed at the ends of enlarged bent caps. This is called a 'superbent' and is a commonly used seismic retrofit to more firmly anchor a bridge into the ground. The simply supported channel beams (upside down bathtub sections) were securely anchored to each other and to the bents. It looks like at some point a water line was attached to the west side of the superstructure.
At the end of the 19th century Union Lumber built a 10 mile long railway to bring redwood logs (that were being deposited into Ten Mile River) to their mill at Fort Bragg. More information on the bridge, the railroad, and the lumber company is available on the Mendocino Model Rail Website.
Pudding Creek Trestle is a 515 ft long wooden bridge that was built by the Union Lumber Company in 1915. The railroad bridge became a truck bridge when the railway was converted to a haul road in 1949. The logging operation ended in the 1970s and the truck bridge became a pedestrian bridge in 2007.
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