Portland's Bridges: Fremont Bridge (2)

The Fremont Bridge crosses the Willamette River several miles upstream from St. Johns Suspension Bridge.

If you look closely at today's photo, you can see St. Johns Bridge under the Fremont Bridge. The Burlington Northern Railroad Bridge 5.1 sits between them, but I think it must be obscured by a bend in the river. It was originally a swing bridge that was converted to a vertical lift bridge in 1989.

We previously looked at the Fremont Bridge on February 17, 2009. Although these through arch bridges are often built as cantilever structures that are held back with towers and cables, the center span of this bridge was built in California, taken apart and reassembled at Swan Island. put on a barge for the 1.7 mile trip to the bridge site, and lifted onto the 'below-deck' part of the bridge.

The Fremont Bridge is a double-deck structure with four lanes of traffic in each direction. At 1255 ft it has the longest arch span in Oregon. We previously studied the Lupu Bridge in Shanghai which will shortly lose its title of having the longest arch span to the Chaotianmen Bridge (with a 5712 ft span), which is also in China.

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

Shanghai, China's Bridges: A2 Expressway Bridge at Longgang

Shanghai is on a peninsula with the Yangtze River (Chang Jiang) to the north and Hangzhou Bay to the south. Its about 100 km from downtown Shanghai to the end of the peninsula on the new A2 Expressway (a toll road). The expressway carries traffic onto the Donghai Bridge that goes 32.5 km into the Bay (to the Yang Shan Islands). If you continue another 600 km to the northeast (across the East China Sea) you'll reach South Korea and Japan.

About 8 km before the end of the A2 Expressway (and the beginning of the Donghai Bridge) is a tubular steel, tied arch bridge. It crosses over a canal but I don't know if this bridge was the most economical choice or maybe it was chosen because people in China really like arch bridges.

Shanghai, China's Bridges: A2 Expressway Bridge at Longgang by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Shanghai's Bridges: Lupu Bridge (4)

This is the view looking north at the Luwan District of Shanghai from the top of the eastern arch of the Lupu Bridge. Although the main arch is 550 m long, it is also part of a 3,900 m long viaduct. A long viaduct is necessary to bring the approach high enough so the arch bridge can avoid river traffic and also to allow traffic to speed above city streets on an elevated expressway.

Construction activity is going at a rapid pace under the bridge as Shanghai prepares for the 2010 World Exposition. Hopefully, all of the effort and money spent on this 'World's Fair' will bring rewards to the people of China and the people of Shanghai. My impression was that the sacrifices for last year's Olympics in Beijing were not sufficiently appreciated or of much benefit to the people of China. I guess such sacrifices are a part of the process of opening up Chinese society to the world.

I know for myself that in the past I was never invited to visit China as an engineer, while I was frequently invited to attend conferences during the great economic boom in Japan. Now, I'm often invited to attend conferences, workshops, and symposiums, and to talk to my Chinese peers.

This is the first bridge that I have shown with four different photographs on my blog. I guess the Lupu Bridge is a little like an elephant. It looks like a totally different creature, depending on where you are standing and what you are looking at.

Shanghai's Bridges: Lupu Bridge (4) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Shanghai's Bridges: Lupu Bridge (3)

Another view of the Lupu Bridge. This photo was taken from the manicured park on the east riverbank.

This bridge is a basket-handle arch, which means the two arch ribs are inclined towards each other. It makes the arch more stable and more resistant to transverse loads. The arches are supported by large pile caps that carry the dead load, live load, wind load, etc. and a portion of the thrusting action of the arches. However, tied cables and stiffened girders at the deck level carry most of the thrust.

It looks like a painter's traveler is tucked behind the arch under the deck. You can see the steel rails under the deck that support the traveler. A big expense of steel bridges is keeping them primed and painted. I'm not sure why the large ship is parked under the bridge unless it is also used to help maintain the bridge.

Shanghai's Bridges: Lupu Bridge (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Shanghai's Bridges: Lupu Bridge (2)

A few kilometers upstream from where yesterday's photo was taken is the Lupu Bridge. This is the bridge I showed when I started my blog on January 26, 2009.

The City of Shanghai had to design and build the world's longest arch bridge in order to cross the wide Huangpu Bridge. While a cable-stayed or suspension bridge can easily span 550 m, this is currently the maximum length for the main span of an arch bridge. However, a bridge in Dubai with a main span of 667 m will be completed in 2012.

The Lupu Bridge is a three span, half-through, tied-arch design. This type of arch bridge was chosen because the soft soil wouldn't be able to support the large thrust of a through arch. Temporary towers were built to support each side of the arch with cables until the final segment joined the two halves together. Cable ties at deck level carried the thrusting action of the arch. The tension in the cables was adjusted before and after the orthotropic deck was built. A good report on the design and construction of this bridge was written by Yue Guiping of the Shanghai Municipal Engineering Design General Institute.

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

New York City's Bridges: Henry Hudson Bridge

In contrast to most big city rivers, the Harlem hasn't had any new bridges built across it in 40 years. In fact, New York City (NYC) seems barely to have funds for maintaining its existing bridges.

Most NYC bridges were part of big expressway projects that had a negative impact on neighborhoods and sustainable development to the area. While the Thames and Seine River bridges are of a comfortable scale for walking across, most NYC river crossings seem to require an automobile.

Henry Hudson was a 17th century sailor who spent a couple of years exploring the area around present day NYC while trying to find the Northwest Passage for the Dutch East India Company. For some reason, much of the northeastern US and Canada was named after him, including this bridge.

The original idea for this crossing was planned by NYC in 1904 to relieve congestion on the nearby Broadway Bridge. It was hoped that the bridge could be completed on the 300th anniversary of Hudson's voyage to New York (in 1609) but the only thing that got built was a pedestal for a statue of Henry in Riverdale where the north end of the bridge would be built. It took Robert Moses, the Triborough Bridge Authority, and the bridge designer David Steinman to get the crossing built 30 years later.

The Henry Hudson Bridge is a fixed, steel plate girder, deck arch bridge with a main span of 840 ft across the Harlem River. The fact that it's fixed means there are no pinned connections along the arch to release moments (and make the analysis easier). The bridge provides 143 ft of vertical clearance and was the longest such bridge when it was built in 1936. Steinman wanted to build a six lane bridge but the bankers didn't think it was warranted and insisted on a four lane bridge instead. David complied, but he designed the bridge so it could carry a second deck, which was built two years later. The initial bridge cost $5 million and the top deck cost another $2 million. It carries four traffic lanes on the lower deck and three lanes on the upper deck.

This design may be efficient, but I find driving on the lower deck of a long span bridge an unpleasant experience. In earthquake country, it can also be a deadly experience. The top deck of the Cypress Viaduct collapsed during the October 17, 1989 Loma Prieta Earthquake killing 41 people. The replacement for the nearby, seismically deficient East Bay Bridge doesn't have a second deck.

More information on the Henry Hudson Bridge is provided (as usual) by New York City Roads. Like many other NYC crossings, this bridge is currently being rehabilitated (at a cost of $50 million). Although it's not listed among the repairs, the bridge badly needs painting (look closely at photo). Without meaning to sound too chauvinistic, I'll just mention that on major California toll crossings, a paint crew can spend their entire career painting one bridge. When they get done priming and painting the entire bridge, they go back to the other end and start over again.

In the background of the photo, we can see the Spuyten Duyvil Bridge in its open position. It carries Amtrak trains and so it only needs to be closed when a train is coming. Because the bridge has only five feet of vertical clearance, ship traffic is stopped whenever the Spuyten Duyvil Bridge is closed.

All of the photos of Harlem River bridges shown during the last two weeks were taken from the deck of a 'Circle Line Cruise' boat that goes around Manhattan Island. As you can tell from the photos, the only bridge that had to be opened for the boat was the Spuyten Duyvil Bridge.

New York City's Bridges: Henry Hudson and Spuyten Duyvil Bridges by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

New York City's Bridges: Washington Bridge

The Washington Bridge consists of two 510 ft long steel arch spans supported on stone masonry piers and with stone masonry arch approaches. This was the first long span arch bridge to use plate girders for the arch ribs.

The bridge is situated between high bluffs in Manhattan and the Bronx with the deck 152 ft above the Harlem River, making it one of the tallest bridges in New York. One of the arches spans over the river and the other spans over railroad tracks and the Major Deegan Expressway.

The bridge was built in 1888 from a proposed design by C. C. Schneider that was pared down to bring the cost to $3 million. It was considered a rival in beauty to the Brooklyn Bridge when it was completed. Although the bridge was built quickly (in two years), at cost, and with considerably less financial scandal than other New York City bridge projects, a controversy concerning bridge commissioners' salaries delayed the opening by several months. Today, the Alexander Hamilton Bridge carries most of the traffic formerly carried by the Washington Bridge.

New York City's Bridges: Washington Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

New York City's Bridges: Alexander Hamilton Bridge

The Alexander Hamilton Bridge carries the Trans-Manhattan Expressway over the Harlem River from Washington Heights to the Bronx. The bridge is 2,375 ft long while the steel arch span over the Harlem River is 555 ft long. The bridge includes on and off ramps to the Major Deegan Expressway and to Harlem River Drive. Robert Moses (in the 1950s) planned this bridge project as part of I-95 in order to get 90% of the $21 million cost to be paid by the federal government.

I-95 crosses the Hudson River on the George Washington Bridge, crosses under parking lots and high-rise buildings as it goes across Manhattan, crosses the Harlem River on the Alexander Hamilton Bridge, and then crosses the Bronx as the Cross-Bronx Expressway. The Hudson River on the west side of Manhattan is 3600 ft wide and requires a suspension bridge to cross it. The Harlem River on the east side of Manhattan is about 400 ft wide and only requires a steel deck arch to cross it. Because I-95 is eight lanes wide, the Alexander Hamilton Bridge is actually two parallel arch structures with four steel ribs to support the wide deck. More information on this bridge is provided by NYC Roads.

New York City's Bridges: Alexander Hamilton Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.