Painted Bridges - Alkaff Bridge (3)

One last photo of the Alkaff Bridge. I really like tubular members for steel bridges. They have good performance well beyond the elastic range and they're more attractive than the I girders and other members usually chosen for steel bridges.

If you look closely, you can see steel caps at the ends of the members. The caps look like they have vents on the end, but that must be an artistic embellishment by the artist (Pacita Abad). I like her signature near the end of the bottom chord. We should all get to sign our bridges with such panache!

On the far side of the river are bridge workers (perhaps the PIRAS rope climbing crew) touching up Pacita's handiwork. They're wearing harnesses and hanging from static lines in a similar fashion to bridge inspectors in California.

Painted Bridges - Alkaff Bridge (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Painted Bridges - Alkaff Bridge (2)

After the historical/political paintings on the Coronado Bridge, it's refreshing to look at the purely abstract and sensory art on the Alkaff Bridge. I think the smaller hand painted circles on the blue and red rails make a nice contrast to the larger, more detailed circles on the structural elements. Pacita's art reminds me of Larry Poons and the Color Field Artists of the 1960s and 1970s. There may also be a Filipino element to her work although she was hardly a folk artist.

This bridge has an interesting structure.  Four parabolic-shaped members descend at midspan to support the deck and then ascend to form triangles with diagonal elements at the supports. There is also a bottom chord along the sides of the deck that ascends slightly at midspan. The diagonals and the bottom chord are in compression and the parabolic elements are in tension. I think the structure is a kind of truss, although it also reminds me of a suspension bridge with it's parabolic shape. We'll take another look at this interesting structure tomorrow.

Painted Bridges - Alkaff Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Painted Bridges - Alkaff Bridge

Singapore has some of the prettiest bridges in the world, including the Alkaff Bridge. It was built in 1997 as part of an effort to improve accessibility to the walkways on each side of Singapore River. The bridge is near where the Alkaff Quay once stood and where Robertson Quay still stands.

The bridge was built to resemble a tongkang (a lightweight boat that was once was a common sight along the river). It's a 180 ft long single span steel through truss pedestrian bridge.

The bridge was painted in 2004 by Pacita Abad, a famous Fillipino artist. She came to Singapore in 2003 and somehow convinced officials to support her plan to paint the bridge. She got Visual Media Works to turn her hand sketches into bridge plans, Nippon Paint to provide 56 different colored paints for the project, and PIRAS rope climbing workers to clean, prime, and paint the bridge. Pacita completed the job (almost a year later) by hand painting the railings. Unfortunately, she died soon after completing this project.

We'll take a closer look at this bridge tomorrow.

Painted Bridges - Alkaff Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Singapore's Bridges: Elgin Bridge

The first bridge to cross the Singapore River was built at this spot in 1819. It linked the Chinese community on the south side of the river to the Indian merchants on the north, and so the roads on each side were called South Bridge Road and North Bridge Road. The street names have remained the same but the bridge has been replaced several times.

The current Elgin Bridge is a tied arch bridge that was built in 1929. It is 46 m (151 ft) long and 25 m (82 ft) wide. It carries the name of the Governor of India at the time that the previous bridge was built at this site (in 1862).  Like the Anderson and Crawford Bridges, it is supported by three concrete arches with heavily reinforced concrete hangers supporting the floor beams and the deck.  Like the Anderson Bridge, there are two traffic lanes between each pair of arches and pedestrian walkways outside of the arches. However, because the Anderson Bridge is near the mouth of the river it is considerably longer than the Elgin Bridge.

Simple concrete cross-framing members provide lateral stability between the arches. Handsome cast-iron lamps are supported on pedestals at the ends of the arches (taken from the previous bridge at this site). Below the lamps are bronze plaques showing a lion striding in front of a royal palm. This is what Sang Nila Utama, the founder of Singapore in 1299, said that he saw when he first landed on the island.

The bridge was refurbished in 1989 and selected for conservation in 2008.

Singapore's Bridges: Elgin Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Singapore's Bridges: Anderson Bridge

We're going to travel up the Singapore River to study a couple of lovely old arch bridges.

The Anderson Bridge was built in 1910 to carry the traffic that was overloading the Cavenagh Bridge (see February 7th), just as the Esplanade Bridge was built in 1997 to carry some of the traffic that the Anderson Bridge could no longer handle.

By now we should be able to recognize the Anderson bridge as a steel tied arch. In fact, we can see the heavy steel tie under the bridge deck.

This bridge has many beautiful details. The pedestrian railing is supported laterally by graceful steel members resting on concrete floor beams decorated with stars. Instead of the cables and concrete hangers we've recently seen supporting the deck, this bridge has large built-up steel members for hangers and slender diagonal members on both sides of the arch.

The bridge is 70 m (230 ft) long and 28 m (92 ft) wide.  There are three arch ribs, with two lanes of traffic between each pair of arches and a pedestrian walkway on the outside of the arches.  The decorative cross-bracing above the arch ribs carry lanterns and there are two masonry arches at each end of the bridge.

Singapore has done a wonderful job of preserving this elegant bridge.  

Singapore's Bridges: Anderson Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Singapore's Bridges: Esplanade Bridge

About two km south of the Crawford Bridge, where the Singapore River pours into Marina Bay, is the Esplanade Bridge. It is a seven span open spandrel arch, 260 m (850 ft) long, 70 m (230 ft) wide, and with eight traffic lanes and two walkways. It is a popular tourist destination, close to museums and theaters, and with excellent views of Marina Bay. On National Day and New Year's Eve the bridge is closed to traffic to allow pedestrians to watch the fireworks displays from the deck of the bridge.

The bridge was completed in 1997 by the Obayashi Corporation but I couldn't find out who designed it. It appears to be more of a folded shell structure rather than a typical arch bridge.  The arch spans are about 35 m (115 ft) long with only about a 2.5 m (8 ft) rise and the deck is unsupported over the piers.  It is an unusual design but a very attractive bridge.

Singapore's Bridges: Esplanade Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Cable-Stayed Bridges: Cavenagh Bridge

Singapore is a wealthy tropical island with a history and laws that encourage a comfortable and civil society. It's a city state, with a very diverse population who have learned to live together. It was a British colony and currently has a parliamentary government dominated by a single party.

Singapore has many handsome buildings, gardens, and a variety of very fine bridges crossing Marina Bay and the Singapore River. The Cavenagh Bridge was designed by the British colonial government, built in Scotland, disassembled, and rebuilt across the Singapore River in 1869. As commerce and trade increased, the bridge became overloaded and was converted to a pedestrian bridge in 1910.

The structure is a suspension, chain-stayed, and through-girder bridge. Instead of cables, it is supported by chains made of steel links that go up through the tower saddle and are anchored into the ground. The bridge and surrounding area are decorated with a variety of sculptures and historic plaques, including the Cavenagh family coat of arms.

The people of Singapore have shown their usual good judgement in preserving this important structure instead of replacing it with a new bridge when it became less economically viable.

Cable-Stayed Bridges: Cavenagh Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution 3.0 United States License.