Oregon's Bridges: Alsea Bay Bridge (2)

A bridge is considered to have a lifespan of 75 years. Some bridge become so popular or are so expensive to replace that extraordinary efforts are performed to keep the bridge in service. Of course, 75 years is somewhat arbitrary. A bridge that is not worn down by heavy traffic or inclement weather and is well-maintained can stay in service well over 100 years. In fact, there are design recommendations to give important bridges a 100 year lifespan (with more concrete cover, more deck reinforcement, etc.).

The original Alsea Bay Bridge was designed by the great Conde McCullough and built in 1936 (see posting for February 5th). It was considered to be one of the finest examples of concrete bridge construction in the United States. It became eligible to be put on the National Register of Historic Places in 1981. However, the harsh salt water environment began to cause corrosion to the reinforcement, and despite efforts to preserve the bridge, it was finally replaced in 1991.

The new Alsea Bay Bridge (designed by HNTB) pays homage to the original structure in several ways. The central arch span resembles the arches on the original structure. The pedestrian observation platforms (with dramatic pylons) were preserved from the original structure. However, the bridge also updates the style from Gothic to Modern with Y-shaped piers and a parabolic line to the arch. The bridge was also modernized with a latex concrete deck and a thicker concrete cover to prevent corrosion of the reinforcement.

Oregon's Bridges: Alsea Bay Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Shanghai, China's Bridges: Wuzhen Road Bridge

The next bridge upstream across Suzhou Creek is a single span through arch with tubular steel ribs.

The Wuzhen Road Bridge is about 60 m long and 20 m wide. Like the Xizang Road Bridge, it has ramps that carry vehicles onto the bridge and stairways that carry pedestrians from the quays onto the bridge.

Suzhou Creek has an interesting history. In 1842 China was forced to open up to foreign trade. Shanghai became a major port and Suzhou Creek was used to bring goods out from China's interior. The banks became heavily industrialized and the water polluted. In 1998 the City of Shanghai began a project to revitalize the area. There was significant new construction as well as work to preserve historic structures. Pollution was stopped and parks and entertainment facilities were built along the creek.

Shanghai, China's Bridges: Wuzhen Road Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License

Tokyo's River Crossings: Suijin Bridge

A little north of the Sakura-bashi on the Sumida River is the Suijin-ohashi, a three span bridge with a through-arch center span. It is a steel bridge, painted bright blue to match it's name of 'water god.' It was built in 1989 but looks almost timeless in appearance. It has areas on the sidewalks (over the piers) where you can stand, lean against the railing, and watch the river flowing by.

Tokyo's River Crossings: Suijin Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Viaduc d'Austerlitz

I took this photo of the Viaduc d'Austerlitz, which is usually silver, while it was being repainted. We must be seeing the primer coat. The scaffolding didn't appear to disrupt the train service, but I didn't see any painters on the bridge. Maybe it was the weekend or maybe they only paint at night.  In the U.S. there are strict rules to prevent old lead-based paint from falling in the river. This usually involves putting a tarp under the bridge to catch all the debris.

Because the Metro track alignment was so low, the arch was put above the deck, to keep it from interfering with river traffic.  The bridge is 140 m (460 ft) long, 8.5 m (2 ft) wide, and has a vertical clearance above the river of 11 m (36 ft).

Large, ornamented stone abutments support the ends of the arch.  The steel arch ribs are decorated with sea creatures and the city's coat of arms. The bridge was designed by the engineer Louis Biette and the architect Jean-Camille Formige and opened in 1904.

Seine River Bridges: Viaduc d'Austerlitz by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.