Seine River Bridges: Passerelle Senghor

The Passerele Senghor is reminiscent of the Pont des Arts with its steel arches and wooden decks.  It was completed in 1999, just after I took this photo. The bridge crosses the Seine on a single 106 m (348 ft) span.  Passerelle means a small bridge and the Passerelle Senghor is a pedestrian bridge with a 15 m (49 ft) wide deck. The bridge is supported by two steel arch ribs joined by steel cross braces that support a second deck. The top deck has a rectangular opening that allows pedestrians walking along the quays to ascend from the bottom to the top deck. It was named after Leopold Sedar Senghor who was a French-educated Senegalese poet and politician.

Seine River Bridges: Passerelle Senghor by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Royal

Although its appearance has changed over the years, the Pont Royal remains a handsome example of late French Renaissance bridge design. This five span stone masonry deck arch was completed in 1689 with money provided by King Louis XIV (hence its name).

The arches are elliptical in shape and they also vary in length with the longest span in the center. Pont Royal was one of the first bridges to use open caissons in its construction. Francosi Romain, a foundation expert from Holland, dredged the river bed to provide a firm level surface and then sank tall caissons that were pumped out to provide a dry place to build the piers.

Pont Royal is 110 m (360 ft) long with spans of 20.6 m (68 ft), 22.7 m (75 ft), 23.5 m (77 ft), 22.4 m (74 ft), 20.6 m (68 ft), and a width of 17 m (56 ft).

The cutwaters at the ends of the piers have conical tiled roofs, the balustrades are unadorned stone barriers, and the bridge was equipped with a gauge to show the previous high flow at this point in the river. It was thought (especially in the past) that the many bridges in the Seine tended to slow the river's flow and contribute to its flooding. More recently, there has been an effort to align the openings of the bridges to allow the river to flow downstream unimpeded.

Almost all the river bridges in Paris are arches. In the past, suspension bridges have been built over the Seine, but their towers and cables are an impediment to views of the city and they were eventually replaced with arch bridges. Paris is fortunate to have a river that is narrow, slow-moving, and shallow. The Huangpu River in Shanghai is over 500 meters wide and people still take ferries or drive across huge bridges to cross it (see January 26th's blog). The Hudson and East Rivers in New York City are also wide and require big bridges that dwarf people and their activities.

The Thames is similar in size to the Seine and affords many pleasant strolls over bridges. Tokyo has three moderately-sized rivers as well as many pleasant arch bridges.

Seine River Bridges: Pont Royal by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont du Carrousel

The Pont du Carrousel is a three span reinforced concrete, closed spandrel, deck arch bridge. It is composed of three 47 m (154 ft) spans, it has a total length of 168 m (552 ft), and a width of 38 m (125 ft).

The bridge combines modern and more classical elements reflecting its age (it was completed in 1939). The arches are flat circular segments.  The deck was built high and so tunnels were provided for pedestrians walking along the quays.  Two stone sculptures (from the previous bridge) sit atop each abutment. The ends of the piers are rounded and topped by conical shapes. The bridge is aligned with the Arc de Triomphe du Carrousel along the right bank. 

Seine River Bridges: Pont du Carrousel by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont des Arts

Just downstream from the Pont Neuf is the Pont des Arts, a seven span steel open spandrel deck arch supported on stone piers and abutments. It was built in 1984 and modeled after the previous bridge at this site.

The bridge spans between the Louvre and the Academy of Fine Arts (within the Institut de France) which is how it derived its name. Moreover, it is used as an open air studio by painters and other artists. It is a very light and airy structure. The bridge deck is made of wooden planks, the barrier rails are an open wire mesh, and the bridge only carries pedestrian traffic.

Seine River Bridges: Pont des Arts by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Neuf (3)

I thought we could take a last look at the Pont Neuf before we continue down the Seine. This photo provides a detailed look at one of the bastions on the bridge with some pedestrians relaxing and enjoying the view.  In the background is a statue of Henry IV,  who was very active in the getting this bridge completed. The original statue was torn down during the French Revolution and rebuilt when the Bourbons returned to power in 1818.

Note that the bridge deck extends well past the balustrade and supports some kind of utility or perhaps it's for the scaffolding that will soon be erected for bridge repairs. The French limestone on this bridge must be sensitive to acid rain, since it looks in terrible shape. They must have replaced a lot of the stonework during the repairs for the bridge's 400th anniversary.

Seine River Bridges: Pont Neuf (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Neuf (2)

A closer look at the 400 year old Pont Neuf. In the photo, we can see that the bastions are supported on cutwaters projecting into the Seine. The deck is cantilevered past the arches, and so we can see corbels under the deck. Since they are made of stone, they must be carefully designed to limit the tension at the top of the cantilever.  If you look closely, you can see that the bottom of each corbel is supported by the head of a bearded man. Also, you can see how blackened and deteriorated the stone of the bastions have become. I took this photo several years ago, before they repaired this side of the bridge. I must be standing on the Right Bank, looking slightly upstream, and towards the Ile de la Cite.  I wonder if they put cutwaters on both sides of the bridge purely for symmetry?

Seine River Bridges: Pont Neuf (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Neuf

The oldest bridge crossing the Seine in Paris is the Pont Neuf (New Bridge). All the older bridges over the Seine were destroyed or replaced. Perhaps the Pont Neuf was preserved because of its noble birth. The first stone was laid by Henry III in 1577. However, the bridge was not completed until 1607 (by Henry IV).

As shown in the photo, the bridge connects the left and right banks to the downstream end of the Ile de la Cite (we are looking upstream, so the left bank is on our right). Seven stone arch spans connect the island to the right bank and five stone arch spans connect it to the left bank. The total length of the bridge is 232 m (760 ft) and it is 22 m (72 ft) wide.  A nice feature of the bridge are the large bastions above the piers that allow pedestrians (and especially tourists) to stand out of the way and look around.

The bridge has been repaired and rebuilt many times including major repair work that was completed in 2007 for its 400th birthday.

Seine River Bridges: Pont Neuf by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont au Change

The Pont au Change is on the Right Bank, on the other side of Ile de la Cite from Pont Saint Michel. Actually, these two bridges look alike except that the Pont au Change is longer. Both are three span deck arches, both carry the insignia of Napoleon III, and both were built in 1857. It is called the Pont au Change because money changers had their shops on the bridge during the Middle Ages.

Seine River Bridges: Pont au Change by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Saint Michel

We are continuing downstream along the River Seine beside the Ile de la Cite.  On the Left Bank just past Petit Pont is the Pont Saint Michel.  We can see the spire of Saint Michel's Chapel behind the Palace de Justice in the photo. The bridge is a three span stone masonry filled spandrel arch bridge. It is 62 m (204 ft) long and 30 m (98.5 ft) wide. It was built during the reign of Napoleon III in 1857 and bears his insignia above the round cutwaters on the piers.

In 1961, during a peaceful demonstration against the French occupation of Algeria, the protestors were attacked by the police and hundreds were killed, many thrown unconscious from this bridge into the Seine.

Seine River Bridges: Pont Saint Michel by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Notre Dame

Pont Notre Dame is on the other side of the Ile de la Cite from the Petit Pont. Like the Petit Pont, it has been destroyed and rebuilt many times. It is 105 m (344 ft) long, about three times as long as Petit Pont, and so it was called the Grand Pont until the Middle Ages.

The current bridge was built in 1919. It is composed of two 14 m (46 ft) long masonry arch end spans and a 60 m (197 ft) long steel deck arch center span. It is 20 m (66 ft) wide with pedestrian, bicycle, and vehicle lanes. Like most river bridges in Paris, it is highly decorated with heads and statues of Greek Gods, Christian Saints, and French Kings.

Like the Viaduc d'Austerlitz, the steel, center span of the Pont Notre Dame was being painted when I took this photo. The problem with metal bridges is that they need more maintenance than stone and concrete bridges. The center span is normally green.

Seine River Bridges: Pont Notre Dame by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Petit Pont

Just downstream from the Pont au Double is the Petit Pont.  There has been a bridge at this location since before the Romans invaded the north. It's been destroyed and rebuilt many times. The Gauls used it to escape from the Romans and they would set it ablaze behind them. In the Middle Ages, Paris was an island (the Ile de la Cite) with the Petit Pont on the Left Bank and the Grand Pont on the Right Bank. The Petit Pont was used by Abelard to visit Heloise, and probably by many other lovers.

The current Petit Pont is a 32 m (100 ft) long single span stone masonry arch bridge. It is 20 m (66 ft) wide and carries vehicles and pedestrians. It has a distinctive keystone, a stairway to a riverside walking path, and one abutment is on the bank while the other is in the river.

Seine River Bridges: Petit Pont by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont d'Aréole

The Pont d'Arcole is just downstream from the Pont Louis Philippe between the Ile del la Cite and the Right Bank. Like several of the bridges over the Seine, it was named after one of Napoleon's victories.

It is a 80 m (263 ft) long single span deck arch composed of fourteen arch ribs connected to the deck with triangular elements. It was built in 1856 of wrought iron, which is more ductile and malleable than cast iron.  Even so, the bridge subsided by 20 cm in 1884, and had to be reinforced with steel trusses. In 1944, it was driven over by the first tanks that liberated Paris. It was more thoroughly waterproofed and repainted in 1995.

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

Seine River Bridges: Pont au Double

We are continuing to look at arch bridges as we travel downstream along the Seine in Paris. By now it is apparent that the state of the practice in the 19th century for river crossings was a single or multi-span stone masonry or cast iron arch bridge. In London along the Thames and in Paris along the Seine, we see arch bridges as the preferred choice for river crossings.

The Pont au Double is a single span, cast iron arch bridge that spans between the Left Bank and the Ile De la Cite next to Notre Dame Cathedral.  A bridge has stood at this site since 1634. The current bridge was built in 1883. It is 45 m (148 ft) long and 20 m (66 ft) wide. Its unusual name comes from the toll (a double denier) that was required to cross the earlier bridge.

Seine River Bridges: Pont au Double by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Louis Philippe

Pont Saint Louis is a continuation of the Pont de l'Archeveche connecting the Ile Saint Louis and the Ile de la Cite (across the Seine). It is a single span box girder bridge.

The next bridge that we will look at is the Pont Louis Philippe that connects the Ile Saint Louis to the quartier Saint-Gervaise. It is a three span, stone masonry deck arch bridge.  It is 100 m (394 ft) long and 15 m (72 ft) wide. King Louis Philippe of France laid the first stone of an earlier bridge near this location in 1833.  The current bridge was opened in 1862.  It has distinctive cutwaters and round openings at the piers. The only change since it was built was that the stone balusters were replaced in 1995.

Seine River Bridges: Pont Louis Philippe by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont de l'Archeveche

I don't have a photo of the Pont Marie (on the other side of the Ile Saint Louis from the Pont de Tournelle). However, I do have a photo of the Pont de l'Archeveche (the archbishop's bridge), just downstream from the Pont de Tournelle.

This bridge is 68 m long, 17 m wide, and 11 m above the Seine.  It was built in 1828 by the engineer Plouard. It is a three span, stone masonry, deck arch.

Seine River Bridges: Pont de l'Archeveche by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont de la Tournelle

Yesterday's bridge, the Pont Sully, crossed the Ile Saint Louis between the left and right banks of Paris. Today's bridge, the Pont de la Tournelle, crosses from the left bank to the Ile Saint Louis. It is a reinforced concrete deck arch built in 1928.  It is composed of small arches at the ends and a long arch in the center. It is 122 m (400 ft) long, 23 m (75 ft) wide, and with only 7 m (23 ft) maximum clearance over the Seine.

Its most unusual feature is a sculpture (on one of the cutwaters) of a church spire with Saint Genevieve standing at its peak. The spire at Notre Dame Cathedral is clearly visible downstream.  This reinforced concrete bridge has rough hewn stone masonry facing stones.

Seine River Bridges: Pont de la Tournelle by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont Sully

Although this website is called 'Bridge Photo of the Day' I'm hoping that two photos will provide a better view of this bridge on both sides of the Ile Saint Louis.

The southern part of Pont Sully (at the left bank) is composed of three cast iron arches (46 m- 50 m- 46 m) separated by masonry piers. The northern part (across the narrower part of the river) is composed of two 15 m (49 ft) masonry arches separated by a 42 m (138 ft) cast iron arch.

Pont Sully was opened in 1877. It may have been named after the architect of the nearby Notre Dame Cathedral.

It replaced two suspension bridges: Passerelle Damiette (on the Right Bank), which was destroyed during the 1848 Revolution and Passerelle de Constantine, which was built in 1638 and eventually collapsed. More information on these deck arches is at Structurae.

Seine River Bridges: Pont Sully by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Seine River Bridges: Pont d'Austerlitz

Pont d'Austerlitz is a five span masonry arch bridge over the River Seine in Paris. It replaced an older bridge that was built in 1805.  The new bridge has five 32 m (105 ft) spans and was 18 m (60 ft) wide, but it was widened in 1884 to 31 m (102 ft). I wonder if the ornamentation on the spandrel walls above the piers was removed from the original bridge and put on the new bridge and on the widening?

Austerlitz is where Napoleon won one of his biggest battles in 1805, the year the original bridge was built.  The ornamentation is of a lion holding up a shield, an image of war.

Seine River Bridges: Pont d'Austerlitz 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.

Seine River Bridges: Pont Charles de Gaulle

The next bridge downstream on the Seine after the Pont de Bercy is the Pont Charles de Gaulle.

This bridge is a steel box girder with a reinforced concrete slab cast on top. There are shear studs connecting the slab to the steel box so that they can act together in bending. The concrete slab is transversely prestressed so that it can span the 31.6 m (104 ft) superstructure width.

Its a four span bridge supported by seat-type abutments and elliptical caissons with oddly shaped steel bearings. Each superstructure segment was manufactured in a plant, brought to the site at night, welded to the previous segment, and then pushed out over the Seine. Perhaps the strange bearings allowed the superstructure to be pushed out with minimum friction. More likely they changed the bearings after construction was completed.

This bridge is 208 m (682 ft) long with spans of 55 m (181 ft), 84 m (276 ft), and 69 m (227 ft). It has wide sidewalks as well as four lanes for one-way vehicle traffic from the Left to the Right Bank.

The winning design was chosen through an international competition in the late 1980's and completed in 1996.  My feeling is that this design (by the architects Louis Arretche and Roman Karasinski) was chosen because its thin section and clean lines don't interfere with the view of the Seine and its surroundings.  

Seine River Bridges: Pont Charles de Gaulle by Mark Yashinsky is licensed under a Creative Commons Attribution 3.0 United States License.

Seine River Bridges: Pont de Bercy

Today we leave the Los Angeles River to travel through Paris along the Seine. The River Seine begins in Dijon and meanders for 776 km (482 miles) before flowing into the English Channel.  It enters Paris between the 12th and 13th Arrondissements and travels through Paris in one big bend of the river.  The Seine flows under three arch bridges (in Paris) before reaching the Pont de Bercy. The Pont National is a five span filled masonry arch bridge on short piers and built in 1853.  The Pont de Tobiac is another five span masonry arch bridge that was built in 1882.  The Passerelle Simone de Beauvoir is a steel lenticular pedestrian bridge (similar in behavior to an arch).  It opened in 2006 according to Archimagazine. 

The Pont de Bercy has the appearance of a Roman double-deck aqueduct. It replaced an inadequate suspension bridge in 1864.  It was originally just a five span, stone masonry, spandrel-filled arch bridge (the lower structure in the photograph). However, in 1904, a second deck was added to carry the Metro line.  In 1986 the bottom deck was widened (using reinforced concrete with a stone facade) to carry more traffic while matching the original structure. 

The current structure has six traffic lanes (three in each direction) along with wide sidewalks on the lower deck.  The bridge is 175 m (575 ft) long and 40 m (130 ft) wide. It carries Boulevard Vincent Auriol and Boulevard de Bercy across the Seine and provides a link between the two arrondissements in the southwestern part of Paris. You would see the Passarelle Simone de Beauvoir (named after the feminist writer) just behind the Pont de Bercy, except it hadn't been built when I took this photo.

Seine River Bridges: Pont de Bercy by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Los Angeles River Bridges: The Glendale Hyperion Viaduct

The Glendale Hyperion Viaduct is a large interchange that carries traffic between Hollywood and Glendale across the Golden State Freeway and the Los Angeles River.  It is about five miles (8 km) north of Broadway Viaduct (the Buena Vista Bridge) which is the next historic arch bridge downstream.

The design of this interchange is credited to Merrill Butler who was the chief bridge engineer for the City of Los Angeles from the 1920's to the 1960's.  It is actually two arch bridges supported on the same long pier walls over the Los Angeles River.  The closer bridge (Glendale Boulevard Bridge) is 316 ft (96 m) long and 27.6 ft (8.4 m) wide. Note the architectural details such as the towers at the ends of the bridge and the pedestals supporting lamps over the piers.  The structure behind it is the Hyperion Avenue Bridge, which is 518.1 ft (158 m) long, 67.9 ft (21 m) wide, and has the same architectural details. Both bridges are reinforced concrete closed spandrel deck arches. 

The interchange includes six bridges as well as plaques and monuments to honor the soldiers who gave their lives during World War I (the interchange was opened a little after the first Memorial Day).

This is an almost a rural setting in the middle of Los Angeles.  The Los Angeles River is allowed to flow somewhat  freely (the channel doesn't have a concrete bottom, trees are growing in the river, and we can see the Verdugos Mountains in the distance) just south of Griffith Park and Los Feliz.

Los Angeles River Bridges: Glendale Hyperion Viaduct by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Los Angeles River Bridges: Atlantic Boulevard Bridge

The Atlantic Boulevard Bridge is a seven span, reinforced concrete deck arch that crosses the Los Angeles River about three miles south of the 26th Street Bridge.  This bridge is 464 ft (141.4 m) long with a maximum span length of 60 ft (18.3 m) and 72 ft wide (21.8 m) from edge of deck to edge of deck with six traffic lanes.  The bridge length is greater than 7 x 60 = 420 ft because the distance is from the beginning of bridge (BB) to end of bridge (EB) which is measured from behind the abutments.

The arches are supported by wide pier walls and by end diaphragm abutments. It was designed by the County of Los Angeles and completed in 1931.  Some of the architectural features of the bridge, like the original lamps that were mounted on pedestals above the piers and abutments have been removed.

Note how wide the Los Angeles River has become. The many railway tracks that followed the river north of downtown have now moved into a trench east of the river. The Alameda Corridor Project eliminated all at-grade railway crossings between the Ports of Long Beach and Los Angeles to downtown Los Angeles http://www.acta.org/. However, the transmission lines still follow the river.

This is the most southern of the architecturally unique arch bridges that cross the Los Angeles River. There are a dozen of these bridges, starting with the Glendale Hyperion Viaduct north of downtown Los Angeles, which we will look at tomorrow.

Los Angeles River Bridges: Atlantic Boulevard Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Los Angeles River Bridges: 26th Street Bridge

We are traveling south from Olympic Boulevard along the Los Angeles River to the City of Vernon.  Both Olympic Boulevard and 26th Street require three spans to cross the river, which continues to widen until we arrive at the estuary in Long Beach. The Los Angeles River's concrete channel gets bigger and bigger to carry all of the runoff that would otherwise flood the region during heavy rains. However, it remains too small to carry anything close to the 100 year flood, due to the reduction of vegetation and soil in the Los Angeles Basin to absorb the runoff.

The 26th Street Bridge was built in 1927 and had additional work done in 2000. It carries only two lanes of traffic and is composed of three 90 ft (27.4 km) reinforced concrete closed spandrel deck arches.  It is supported by squat, rectangular, single column bents and end diaphragm abutments.  It has some of the architectural features similar to the other arch bridges such as a knobby texture between the arches and the deck, floor beams that support the cantilevered deck, and nice details at the bents. The street lamps over the abutments and bents, if they once existed, are now gone.

This photo looks north at downtown Los Angeles.  We can see the Los Angeles City Hall and the Hollywood Hills in the background. A good reference is at http://bridgehunter.com/ca/los-angeles/53C0868/

Los Angeles River Bridges: 26th Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Los Angeles River Bridges: Olympic Boulevard Viaduct

I don't have a good photo of Olympic Boulevard Viaduct (a viaduct is a bridge composed of many spans). This viaduct is 1/4 mile south of the busy Santa Monica Freeway, 1/2 mile north of East 20th Street, and there are locked gates along the Los Angeles River so it was hard to get a good photo.

When I visited the viaduct in 2000, it was being taken apart for a seismic retrofit combined with some general maintenance.  The beautiful balusters in the photo are new and made using glass fiber reinforced concrete to match the original railing. The lampposts were removed for repair and temporarily replaced with strictly utilitarian lamps. The ornamental pylon supporting the lamp is obviously the original.  This bridge is in the same Beaux Arts style that was used on many of the arch bridges. The retrofit, like most arch bridge retrofits, involves tying the deck together at the expansion joints in order to carry the inertia force to the end piers. An additional requirement was that the retrofit had to be hidden from the public to preserve the aesthetics of the original structure. It was designed by Dokken Engineering and cost $9 million. More information is at LACity.

The Ninth Street Viaduct was built in 1925 but got its name changed (as well as the name of the boulevard) in honor of the 1932 Los Angeles Olympics.  Trolleys once ran up and down the boulevard and so a stronger girder and a thicker deck were provided along the middle of the viaduct.  The structure is 1,422 ft (433 m) long, with three open spandrel reinforced concrete deck arches over the Los Angeles River and with reinforced concrete T-girder spans that cross over many railway tracks on both sides of the river before descending to the ground. Very substantial piers that are well-anchored into the soil were required at the ends of the arch spans to resist the longitudinal arch force.  The designer of record was Los Angeles city engineer Merrill Butler whose staff must have designed every arch bridge in downtown Los Angeles.

Los Angeles River Bridges: Olympic Boulevard Viaduct by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.