Monday, May 31, 2010

Movable Bridges - Kinzie Street Bridge (1)


In the shadow of the railroad bridge sits the Kinzie Street Bridge across the North Branch of the Chicago River. The North Branch flows into the South Branch and then into the Chicago Sanitary and Ship Canal, which was built to reverse the river's flow and improve sanitation in the 1900s.

The Kinzie Street Bridge was built in 1909. Its a single leaf bascule Pratt truss bridge and provides 105 ft of channel clearance when its open. We are looking at the trunnion side with racks along its rounded end. The operating machinery has pinion gears inserted into the racks that rotate the bascule span up and down (with the help of the counterweight). We'll take another look at this interesting bridge tomorrow.
Creative Commons License
Movable Bridges - Kinzie Street Bridge (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Sunday, May 30, 2010

Movable Bridges - Kinzie Street Railroad Bridge (2)


Looking at the Kinzie Street Railroad Bridge from the side, we can see that the large concrete counterweight isn't hidden in a pit like the bridges around Wacker Drive. Apparently aesthetics isn't as big of a concern on the North Chicago River. Still, its a Chicago landmark, so the community must like this big, ugly structure.  We can see two sets of tracks on the through truss deck, and a crummy little operator's house instead of the exquisite tender houses along Wacker Drive.

The superstructure was built by the Strauss Bridge Company and so one of his patented devices pulls the superstructure into the air as the counterweight rotates onto the deck.

There's a lot of laced members on this bridge which were popular during the turn of the 19th century although today they need to be replaced with something more ductile in earthquake regions. The raised span is 170-foot long (tall?) and is supported on the east trunnion pier. According to Wikepedia, it was constructed on foundations 94 feet down into bedrock. A caisson was built to a depth of 29 feet below the river bed and then holes were drilled that eventually caused the caisson to drop the remaining 65 feet. I guess that's why the bridge is still around 100 years later, although it is now functionally obsolete.
Creative Commons License
Movable Bridges - Kinzie Street Railroad Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Saturday, May 29, 2010

Movable Bridges - Kinzie Street Railroad Bridge

Movable highway bridges usually stay closed while railroad bridges stay open. However the Kinzie Street Railroad Bridge is always open because the tracks have been removed for the Chicago Sun Times Building.

This bridge was built in 1908 and at the time it was the largest single leaf bascule bridge in the world. The superstructure was built by the Strauss Bascule Bridge Company and the huge substructure was built by the Great Lakes Dredge and Dock Company.

The bridge remains open as a Chicago landmark on the North Chicago River, looking a little like Claes Oldenburg's Batcolumn which is nearby on Madison Avenue.

We'll look at the bridge from the other side tomorrow.
Creative Commons License
Movable Bridges - Kinzie Street Railroad Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Friday, May 28, 2010

Movable Bridges - Van Buren Bridge from Jackson Street Bridge

The West Van Buren Street Bridge is at the south end of Wacker Street across the Chicago River. This photo shows the steel deck of the West Jackson Street Bridge and the West Van Buren Street Bridge to the south.

The West Jackson Street Bridge is one of the earliest bridges across the Chicago River (built in 1916). It is a steel deck truss designed by the Strauss Bascule Bridge Company.

The West Van Buren Street Bridge was one of the last bridges built across the Chicago River (in 1956). Like several other Chicago River bridges, this one has a steel truss that goes above the deck and acts as the railing between the concrete sidewalk and the steel roadway.
Creative Commons License
Movable Bridges - Van Buren Bridge from Jackson Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Thursday, May 27, 2010

Movable Bridges - West Adams Street Bridge

Chicago is such a great looking city, that I seem to be having trouble focusing on the bridges instead of the surrounding buildings. We are quite a bit farther down the South Branch of the Chicago River now, just a couple of blocks from the Sears Tower (now the Willis Tower), which is sadly the tallest building in the U.S. since the destruction of the World Trade Center Towers.

The West Adams Street Bridge is a deck truss double leaf bascule bridge with a 173 ft clear span and a 64 ft width, making it one of the smaller bridges across the Chicago River. Like all the other bridges, it has pits on the two ends to keep the counterweights out of sight (and out of the way). Comparing these Chicago River bridges with the previously studied heel trunnion bascule bridges across the Sacramento River shows how much cleaner the bridge's appearance is when the counterweights are concealed.

I wonder if Prof. Billington at the University of Princeton would prefer the Sacramento River bridges where we get to see the structure that opens and closes the bridge?

I've been wanting to mention that most of the information on these bridges is from James S Phillips who wrote an excellent history of these bridges, which I purchased for only $3.75, a real bargain! I like the idea that you can write a book, post it on the Internet, and sell it without the need for a publisher, distributors, etc.
Creative Commons License
Movable Bridges - West Adams Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Wednesday, May 26, 2010

Movable Bridges - West Lake Street Bridge

About a mile downstream from Lake Michigan, the Chicago River splits into a north and south branch. Traveling a little bit to the south, we come to the West Lake Street Bridge. This is a huge, double deck through truss, double leaf bascule bridge. There are two sets of train tracks on the top deck and four traffic lanes and sidewalks on the bottom deck.

This big, boxy bridge is less attractive than the more streamlined pony and deck trusses across the Chicago River. It carries over 500 trains a day and so a vertical lift bridge was originally planned for this site. However, aesthetic concerns prevailed and a bascule bridge was eventually built in 1916.
Creative Commons License
Movable Bridges - West Lake Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tuesday, May 25, 2010

Movable Bridges - North Clark Street Bridge

The next bridge I photographed was at Clark Street. It was always the main north-south route through town and so a floating timber bridge was built at this location across the Chicago River in 1840. It was destroyed by a flood in 1849 and replaced with a timber swing bridge in 1854. The Great Fire of 1871 destroyed all the bridges across the Chicago River but they were rebuilt the following year.

The North Clark Street Bridge was the last of the swing bridges that were replaced in downtown across the Chicago River (by a pony truss bridge in 1929) . It has a clear span of 215 ft, a width of 72 ft, and each leaf weighs 2800 kips.

Today, these bridges are only opened about 40 times a year. Note how the trusses becomes deeper at their ends to support the counterweights as they rotate into the pits behind each tender house. The North Clark Street Bridge was rebuilt many times, with the last rehabilitation in 1985.
Creative Commons License
Movable Bridges - North Clark Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Monday, May 24, 2010

Movable Bridges - North State Street Bridge

The Chicago River was an important waterway long before there was a city along the southwest shore of Lake Michigan. People in the northeastern United States could go from the Great Lakes onto the Chicago River and travel all the way to the Mississippi River.

Today the river cuts a narrow swath through the skyscrapers of downtown Chicago. There are eighteen bascule bridges crossing the river along Wacker Drive. These bridges are dwarfed by the surrounding buildings.   Most of the bridges were built in the early 20th century at the height of the City Beautiful Movement. It was felt that vertical lift and swing bridges weren't attractive enough for the architectural milieu.

The devices that control the movement of bascule bridges are often patented, and so the Chicago DOT engineers developed their own machines to lift the bridge spans. These bascule bridges have through truss, deck truss, and double-deck truss superstructures, but they all use counterweights in pits, architect-designed tender houses, and other recognizable features.

The North State Street Bridge is the fifth bridge across the Chicago River west of Lake Michigan. It provides a clear span of 210 ft and an extremely wide 108 ft that includes six traffic lanes and two sidewalks. Its a deck truss (the truss penetrate the deck as bridge railings) that was built in 1949, although there has been a movable bridge at this site since 1864.
Creative Commons License
Movable Bridges - North State Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Sunday, May 23, 2010

Movable Bridges - Meridian Bridge (2)

I'm standing on the deck of the Meridian Bridge. In the distance you can see the Sutter Buttes, which are the remains of some old volcanos.

The steel tower supporting the swing span is a model of simplicity. The tubular legs on each side of the deck come together at the top and are braced with a strut. The cables come up from two floor beams, through the top of the tower, and then are attached to two floor beams on the other side.

I often wondered why the swing span of this type of bridge doesn't bang into the corners of the side spans when it moves. I looked closely at the gap between them and saw that it was curved, probably to the circumference of the circle the swing span makes as it rotates about the pivot span.
Creative Commons License
Movable Bridges - Meridian Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Saturday, May 22, 2010

Movable Bridges - Meridian Bridge

This is the last movable bridge I have photos of on the Sacramento River. However, there are a few more movable bridges up north that I hope to photograph (maybe during the summer).

Bridge engineers are faced with a challenge providing a big enough channel opening with a swing bridge. Because the support is in the center, it's difficult to make the cantilever spans on each side large enough for ships to pass. We saw that the Spokane Street Bridge (April 28th and 29th) has a swing span on each side of the channel so that a very large opening can be created. The other swing bridges we looked at had truss superstructures to provide long stiff cantilever spans. The Meridian Bridge solves the problem in a different way, with a central tower and a cable stays to support the cantilever spans.

This bridge carries State Route 20 across the Sacramento River a little south of Colusa and a little west of Marysville. It was built in the 1970s (and along with the Spokane Street Bridge) provides a good example of how engineers can develop new solutions to address some of the disadvantages inherent with swing bridges. The tower is 50 ft tall and the leaves are about 180 ft long, providing a suitable opening for ships to pass.

We'll take a closer look at this interesting bridge tomorrow.
Creative Commons License

Friday, May 21, 2010

Movable Bridges - Knights Landing Bridge (3)

A last look at the Knights Landing Bridge. Its a double leaf simple trunnion bascule bridge that carries State Route 113 over the Sacramento River. The counterweights are enclosed in the large bin-type abutments.

Balancing the bridge leafs with the counterweight requires careful planning. Because traffic travels on approach spans rather than directly on the counterweights, this bridge is more stable in the closed position. When the locks are opened at midspan, the bridge can be raised with a smaller motor than would be needed if the deck had been made heavier to resist the counterweight and live load behind the trunnion.

I believe this bridge can still be operated. At least, it looks in good shape. Perhaps it is only opened when a request is made to the U.S. Coast Guard several days in advance.

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

Thursday, May 20, 2010

Movable Bridges - Knights Landing Bridge (2)

A view from the deck of the Knights Landing Bridge. In this view, we can see the top chord of the bascule span going through a slotted hole in the approach slab.  The trunnion must be a little bit in front of the approach slab, the counterweight sits below the slab, and it descends into the bin-like abutment when the operator raises the bridge.

This area has changed a lot over the years. When Dr. Knight first came here, this was a meeting place of Native Americans living along the Sacramento River and Cache Creek. A town and ferry were built to handle all the traffic moving along the river, but now its like a ghost town.
Creative Commons License
Movable Bridges - Knights Landing Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Wednesday, May 19, 2010

Movable Bridges - Knights Landing Bridge (1)

North of Sacramento are several interesting movable bridges across the Sacramento River.

The Knights Landing Bridge is the first double leaf bascule bridge across the river that isn't a through truss. I'm actually not sure what kind of structure it is. Are those pony girders with rectangular openings or is it some kind of Vierendeel truss?

I'm also not sure what kind of bascule bridge it is. Is it a double leaf simple trunnion bridge or is it a Scherzer rolling lift double leaf bascule bridge? I vote for the latter since the bridge is high up with counterweights that can pivot into the concrete boxes at the far ends.

The bridge carries State Route 113 over the Sacramento River in the town named after Dr. William Knight, a physician who founded the town of Knights Landing on an ancient Native American mound in 1842.

We'll take another look at this unusual bridge tomorrow.
Creative Commons License
Movable Bridges - Knights Landing Bridge (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tuesday, May 18, 2010

Movable Bridges - I Street Bridge (2)


A closer look at the I Street Bridge. A swing railroad bridge has stood at this site since 1858. The current double-deck bridge was built in 1911. Note the round pivot pier supporting the swing span.

This bridge is 840 ft long with a 340 ft long swing span.A 34 ft tall boat can pass under it at low tide. Otherwise, the captain must signal to the bridge operator to get through. Boaters need to check with the US Coast Guard when planning a trip to find out the bridge's hours of operation,

Swing bridges, and especially swing railroad bridges are more complicated than bascule or lift bridges. Not only do they need locking devices that open and close, but the railroad tracks need to be retracted to open the bridge and extended for trains to pass. There are also devices to help the bridge resist wind (and seismic) loads.

This is one of the largest center bearing swing bridges ever built. It weighs about 6800 kips. At the turn of the 19th century, such big swing bridges had rim bearings with rollers along the perimeter. When this large bridge was successfully built and operated with a center bearing, no one wanted to go through the trouble of fabricating the conical rollers that supported a rim bearing swing bridge and they were no longer built.
Creative Commons License
Movable Bridges - I Street Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Monday, May 17, 2010

Movable Bridges - I Street Bridge


I'm standing in downtown Sacramento looking across the river at the I Street Bridge, the CalSTRS Building, and the Sacramento Pyramid (or Ziggurat).

This double-deck swing bridge carries two sets of railroad tracks on the bottom deck and motor vehicles (and pedestrians) on the top deck. The swing mechanism is still very active. The bridge was built by the American Bridge Company in 1912 and its currently owned by Union Pacific.
Creative Commons License

Sunday, May 16, 2010

Movable Bridges - Tower Bridge (2)

The Tower Bridge spans the Sacramento River on a straight line from the state capitol on M Street into West Sacramento. My feeling is that Sacramento has changed a lot since the bridge was built.

For instance, at the turn of the 19th century, Sacramento was a railroad town and a swing bridge carrying the Sacramento Northern (SN) Railroad was built at this site in 1912.  The Tower Bridge replaced the swing bridge in the early 1930s but continued to carry the SNRR (along with cars and pedestrians) until 1962.

In this photo you can see the cables attached to the lift span (and counterweights). The total bridge length is 737 ft, the roadway is 52 ft wide, the lift span is 209 ft long, and the towers are 160 ft tall (and supported by 50 ft deep caissons).

Creative Commons License

Saturday, May 15, 2010

Movable Bridges - Tower Bridge

I hope that readers expecting to see a Thames River bridge aren't too disappointed. This Tower Bridge is often used as the symbol of Sacramento, which is the capitol of California. However, the towers aren't as architecturally splendid, perhaps because it's too far from Hollywood (and Disneyland).

For some reason, there has been a continuing controversy about the color of this bridge. It was originally silver, but people complained of the glare and it was repainted yellow, which people found dull. Voters got to pick its current color which was meant to be gold but some think is still too dull.

This is the third vertical lift bridge we've looked at on the Sacramento River. It's one movable bridge that is still fairly active. It has 131 ft of vertical clearance and 170 ft of lateral clearance when it's open. It was the first vertical lift bridge in California (built in 1931) and an early example of the 'high-tech' look in engineering (similar to the George Washington Bridge over the Hudson). We'll take another look at this bridge tomorrow.
Creative Commons License


Friday, May 14, 2010

Movable Bridges - Jefferson Blvd. Bridge (obsolete)

The next movable bridge upstream along the Sacramento River was supposed to be the Jefferson Boulevard Bridge over the Sacramento Deep Water Shipping Channel. The book Movable Bridge Engineering said it was a bascule highway and railway bridge built by the US Army Corps of Engineers in 1961.  However, when I rode my bike to West Sacramento, all I could find was an operator's tower (probably for the nearby floodgates), a pony truss highway and railroad bridge, and a new precast I-girder bridge.

My bridge log says the I-girder bridge was built in 2005 and the truss bridge was renovated in 2005 (Movable Bridge Engineering was copyrighted in 2003). I'm guessing the I-girder bridge replaced the bascule bridge, but how did the railroad end up on the existing truss bridge?

The city of West Sacramento has been spending a lot of money on infrastructure, including the Palamidessi Bridge and Overhead (barely seen in the distance) and improving the crossing at Jefferson Boulevard to four highway lanes and a pair of railway tracks (the crossings are called the Sacramento Deep Water Canal Bridges). West Sacramento used to be empty land and industrial parks, but now there are subdivisions on both sides of the canal.

Creative Commons License
Movable Bridges - Jefferson Boulevard by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Thursday, May 13, 2010

Movable Bridges - Jibboom Street Bridge (2)

The American River empties into the Sacramento River just west of the Jibboom Street Bridge. There are many other rivers in Northern California that flow out of the Sierra Nevada Mountains into the Sacramento River. However, since much of the American River is whitewater rapids it's hard to understand why a movable bridge crosses it. Perhaps that's why the swing mechanism hasn't worked in many years. The bridge sits on a huge, cylindrical pivot pier and the two ends rest on piers that also support Parker truss spans. As I mentioned before, swing bridges are hardly ever built and are slowly being removed from waterways. The big exception is the previously studied Spokane Street Bridge in Seattle (shown on the April 29th and 30th blogs), which is huge, with the piers built outside the channel, and has won several design awards.
Creative Commons License
Movable Bridges - Jibboom Street Bridge (2)by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Wednesday, May 12, 2010

Movable Bridges - Freeport Bridge (2)

A view from the east side of the Freeport Bridge. Movable bridges often have open grid decks to reduce their weight. However they can be scary if you are riding across them on a motorcycle or a bicycle.

The east side of the bridge has a pony truss approach span, a through truss span, and then the bascule spans. The west side has a steel stringer approach, so it must be slightly shorter.

North of Freeport, State Route 160 ends, the road becomes Freeport Boulevard, and highway traffic switches to nearby I-5 into the City of Sacramento.
Creative Commons License
Movable Bridges - Freeport Bridge (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Tuesday, May 11, 2010

Movable Bridges - Freeport Bridge

Just south of Sacramento in the tiny town of Freeport is another bascule bridge across the Sacramento River. It's nearly identical to the Paintersville Bridge, only painted green instead of yellow.

The Freeport Bridge was built in 1930 and carries traffic between SR160 on the east side of the river and SR E9 on the west side. It has more elaborate fenders protecting the piers on each side of the 200 ft channel opening, perhaps because it sits next to a dock lined with weekend pleasure craft.

The spaces around the huge counterweights are so tight, that its remarkable that the truss members never get hit as the weights swing past. There must a large industry of mechanics and engineers whose job is to constantly maintain these massive machines. Movable bridges are much more dangerous than fixed structures. Every year people in a hurry or who aren't paying sufficient attention die while trying to cross a bridge that is moving or open.  There's hundreds of these bridges in California and thousands of them in the U.S. However, my feeling is that it's cheaper to build a long tall bridge over a river, rather than to put up with all the problems of owning a movable bridge.

We'll take one more look at the Freeport Bridge tomorrow and then continue up river into the City of Sacramento and beyond to study a few more movable bridges.
Creative Commons License

Monday, May 10, 2010

Movable Bridges - Sutter Slough Bridge

Like the previously studied Steamboat Slough and Three Mile Slough Bridges, the Sutter Slough Bridge crosses a tributary flowing into the Sacramento River. Movable Bridge Engineering lists Sutter Slough as a fixed swing bridge (by which I assume it means it no longer can move). There's a lot of old bridges that can't move, probably because no ships or barges travel past anymore.

I believe swing bridges were more popular before WWII when they were thought to be economical and there was less objection to having a pier in the middle of the waterway. After the war, the US government would help pay the cost of replacing or removing obstructions in waterways. Most of these obstructions were old swing bridges.

Sutter Slough Bridge was built in 1939 in Courtland California. The swing mechanism sits on a three column bent. The bridge carries two-way traffic (on two lanes), it has a total length of 397 ft, and it carries an average of 6020 vehicles a day.
Creative Commons License
Movable Bridges - Sutter Slough Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Sunday, May 9, 2010

Movable Bridges - Paintersville Bridge

In the late 1910s, Sacramento County improved the road between Isleton and Paintersville and provided free ferry service across the river at these two towns. The ferries were replaced with bascule bridges in the early 1920s. The two bridges are almost identical, except the Isleton Bridge has tied arch approaches and the Paintersville Bridge has through truss approaches. They both have the Joseph Strauss patented heel trunnion double leaf spans for a 200 ft channel opening. They are both on concrete piers with timber piles protecting the piers at the channel opening. The two bridges are about 20 miles apart. Thirty years later the bridge at Walnut Grove was built between the older bridges.
Creative Commons License
Movable Bridges - Paintersville Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Saturday, May 8, 2010

Movable Bridges - Three Mile Slough Bridge

I found that I skipped an attractive vertical lift bridge on my march up the Sacramento River. I thought we might as well go back and take a look at it as a break from all the bascule bridges. Actually, I've learned quite a bit about bascule bridges by reading Movable Bridge Engineering by Terry L. Koglin. I think they are more complicated and interesting than the generally simpler lift and swing bridges, but still its nice to enjoy a change.

The Three Mile Slough Bridge is actually a little south of the Rio Vista Bridge, across one of the sloughs that twist and turn in California's Inland Delta. I imagine it's easy to get lost, even with a GPS device, when traveling by boat through the hundreds of islands.

At one time Three Mile Slough must have been an important waterway to have merited such a big bridge. Perhaps the slough is still used to carry ships and barges into Stockton. I like the counterweights with their unusual shapes. I also like the chains hanging from the counterweights, although I'm not sure what they're for. This bridge is much simpler than the Rio Vista Bridge with its parabolic-shaped top chord. It looks like the operator's house sits on top of the lift span!

The Three Mile Slough Bridge was built in 1949. It's 750 ft long and provides 105 ft of vertical clearance and 150 ft of channel width. Apparently the bridge is in poor shape although (or because) it carries about 1000 vehicles a day. It's a steel, vertical lift, through truss bridge with long approaches and a 175 ft long lift span.

I realized that the reason I see so few big ships on the Sacramento River these days is because they built a shipping channel just west of the river. The channel is straight and wide compared to the meandering Sacramento River.
Creative Commons License
Movable Bridges - Three Mile Slough Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.