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— by Julie Sneider, Assistant Editor
Many railroads are spending record levels on maintenance-of-way projects this year, with major bridge projects landing high on their list of priorities. In some cases, the work is necessary as part of broader plans to maintain states of good repair; in others, to replace worn-out bridges so new ones can handle heavier loads and faster trains.
Some structures are being built for special purposes, too: Alaska Railroad Corp. is constructing a bridge over the Tanana River that will improve U.S. military access to important training facilities; and Norfolk Southern Railway’s 2012 projects included modifying two bridges to accommodate tall and wide equipment for two utility plants.
Still other railroads, like CSX Transportation, are replacing and upgrading bridges as part of a broader strategy to solicit more business in certain corridors.
One of CSXT’s major bridge projects this year involved an upgrade of a main corridor in the Decatur Subdivision in Illinois, where the railroad replaced 14 aging, light-capacity timber bridges with heavy-capacity steel and concrete structures. The project was started in 2011 and completed this fall in a corridor “where we’re looking to increase our speed and our abilities as far as heavier loads are concerned so that we can compete for business in central Illinois,” says Ed Sparks, assistant chief engineer of structures at CSXT.
“Each year, CSX is investing more in our bridge infrastructure to help meet the needs of our customers and our transportation needs,” he says. “We focus on a lot on timber bridge elimination because timber doesn’t have the life span of the more modern steel and concrete methods of construction, and it also is not as suitable to the heavier actual loadings that all railroads are experiencing year over year.”
CSXT typically focuses on bridges most in need of upgrades, but in this case the railroad focused on improving bridges along a key corridor.
“In addition to addressing a bridge need, we’re also addressing a competitiveness need and corridor integrity,” says Sparks.
Another major CSXT bridge project involved the replacement of a through-pin truss span in Livingston, Ky., on a line that runs from Cincinnati south to Knoxville, Tenn., and on to Atlanta. The railroad used a 1,000-ton crane to do the work — one Sparks believes may have been one of the largest cranes CSXT has used on a project.
Using the crane also provided worker safety and productivity benefits.
“The typical construction for that type of bridge would require us to build the new spans to the side of the old spans on full falsework, and then slide the old [spans] out and slide the new ones in,” Sparks says. “Utilizing such a substantial crane allowed us to avoid that falsework, and the new spans were delivered and decked … on the ground, which is an improvement in speed and safety. We were able to pick up the old span and set it on the ground so that it could be dismantled not above the river, but in a much safer location.”
While a massive crane helped speed up completion of the Livingston project, Hurricane Irene in 2011 delayed until this year CSXT’s completion of a project to replace four of six double-track spans on a bridge over the Mohawk River in Hoffmans, N.Y. Crews replaced two 1900-vintage spans and two built in 1928, which represented about 440 feet, or two thirds, of the bridge’s length, Sparks says.
Crews first built a temporary structure known as “falsework” on both sides adjacent to the existing bridge; then the new spans were assembled and slid into place. The project allowed CSXT to increase train speeds from 25 mph to the 40 mph, Sparks says.
Kansas City Southern also is focused on replacing existing timber bridges. This year, KCS launched a multi-year program to replace them with concrete and steel structures in the Sabine River bottoms area on the Beaumont Subdivision in Texas, said Vice President of Engineering Jeff Songer in an email.
Construction on two of the structures — Bairds Bayou Bridge and the Sabine River Bridge — is under way, he said. Also on the bridge program docket is the start of a four-year project to replace 5,000 lineal feet of a timber Red River Bridge in Texarkana, Texas, on the Shreveport Subdivision.
“The new bridge will be constructed as a ballast deck bridge including drill shafts, concrete caps and a concrete bulb tee beam concrete deck,” Songer said. “The new bridge will be built parallel to the existing bridge on a new alignment. As the new bridge crosses a major river, environmental permits from various agencies, including federal agencies like the Army Corps of Engineers and Coast Guard, … are being obtained.”
At NS, replacing older wooden structures represented the bulk of the 2012 bridge program. But next year, the railroad plans to start some “fairly major projects,” including the replacement of the Portageville Bridge that crosses the Genesee River in Letchworth State Park in New York, says Jim Carter, NS’ chief engineer of bridges and structures.
With the New York State Department of Transportation, NS plans to build a new, 963-foot-long bridge with a 493-foot steel arch span on a parallel alignment south of the existing bridge, an 819-foot-long steel viaduct with a single track. Built in 1875, the bridge is on NS’ Southern Tier Route.
As of mid-October, design of the new bridge was being developed and NS was “working through” the environmental impact statement, Carter says. NS officials hope construction can begin in 2013 and be completed in 2015. What will become of the historic bridge after the new one is finished hasn’t been determined. The current project cost estimate is $68 million, but all funding sources haven’t yet been identified, he says.
Replacing aging structures has been an ongoing priority at CN, as well. Among the Class I’s major projects in 2012: replacing four spans on a bridge over the Etchemin River in the Montmagny Subdivision in Quebec, and replacing an existing 480-foot long, single-track bridge on the Neenah Subdivision in Oshkosh, Wis.
About 50 percent of the Class I’s bridge spans are more than 100 years old, at which point span replacement becomes more economical than repairs, says David Cook, manager of bridges and structures for CN’s Champlain region in eastern Canada, which includes the Montmagny Subdivision.
“Locomotives have gotten heavier, cars have gotten heavier and we travel faster. No matter how much we repair spans, after a while they won’t do the job anymore and you have to replace them with much stronger, heavier structures,” says Cook.
CN recently began using a mobile gantry system for span replacements — a technology that Cook says will help the Class I complete the projects more quickly, resulting in less down time for train traffic. Developed by Western Mechanical in Toronto in collaboration with CN, the mobile gantry system was used successfully on the Etchemin River bridge project, Cook says. The gantry lifts, removes and installs spans from above the bridge without the need for a crane and associated crane pad.
“It’s a huge efficiency gain, and a huge gain on the environmental front,” says Cook. “Those river bottoms can be sensitive environments, and any time you go into a water course, you need to get an environmental permit to make modifications to the river on a temporary basis.”
Although the mobile gantry system wouldn’t be cost effective or appropriate for every span replacement project, CN plans to use it again if and when it makes sense, Cook says.
“The fact that we can do our work in such a short time means less shutdown time for our operations, which is very, very important in keeping the railroad flowing,” he says. “With Precision Railroading at CN, it’s important to us that our train service plans are accurate.”
The mobile gantry span was not used in the ongoing, multi-year Oshkosh Bridge replacement project in Wisconsin. Constructed in 1899 by the Chicago & North Western Railroad, the bridge over the Fox River consists of three steel through-trusses and a center moveable swing span that provides two navigation channels, according to CN. The replacement structure will be an open-deck bridge with seven steel spans, including a moveable bascule span that will provide a 125-foot navigation channel. A new substructure will consist of six concrete pier shafts, each eight feet in diameter.
The entire project is slated for completion in May 2013. Last month, crews replaced the approach truss spans, and because the new bridge is on the same alignment, the railroad had just two 12-hour periods to complete the work while traffic was shut down, says Mark Paull, CN’s construction engineer for the project.
Constructing a new bridge on the same alignment as the old one presents significant challenges, he says. A lot of the work, including construction of the new bridge’s substructure, must be completed while traffic is moving. And when traffic has to be stopped — such as during the span replacements — crews have narrow time windows to complete the task.
“One of the most challenging aspects of the project will occur in March, when we are scheduled to flow in the moveable span,” Paull says. “It’s going to be under a 40-hour work block. Not only will we be under the gun for getting the traffic back flowing over the bridge, it will be a challenge to get the moveable span in place and to operate as intended — all in 40 hours.”
For Alaska Railroad Corp. (ARRC), seasonal weather is a challenge for bridge work associated with the Northern Rail Extension Project, an 80-mile extension from ARRC’s terminus near Eielson Air Force Base near North Pole, Alaska, to a point near Delta Junction. The project’s first phase involves construction of a 3,300-foot-long bridge across the Tanana River, which when completed will be the longest bridge in Alaska, says Mark Peterburs, ARRC’s project manager.
Bridge construction began in September 2011 with the building of an 11,000-foot levy, which was substantially completed in July. The bridge is being built off a temporary access causeway consisting of a 40-foot-wide road made of riprap amid a series of 38-foot-long bridges to keep the river water flowing.
A unique element of the project is that the roadway must be removed every year — usually in April — because the river freezes in winter and, come spring, “quite a bit of ice travels down the river,” says Peterburs.
“We have to pull the causeway out of the river, allow the ice to pass and then we build it out again to continue working on the permanent bridge,” he says.
How long it takes to rebuild the causeway each year depends on the weather. This year, work on the causeway began in July and was completed by mid-September, when work on the bridge pier, concrete and piling could begin.
“We hope to get 14 to 15 piers completed before we have to pull the causeway out in late April or May; then we’ll wait for the ice to melt and flow down the river, and that is accompanied by high-water events,” Peterburs says. “Hopefully, in July [of 2013] we’ll be able to go back out with the causeway and finish the remaining piers and set the bridge girders.”
ARRC officials anticipate the entire project will be completed by August 2014.
Amtrak won’t be waiting that long to cap off a major bridge project. The railroad is replacing the Niantic River Bridge in East Lyme, Conn., one of five movable structures in the Northeast Corridor. Built in 1907, the Niantic is the most active of the moveable bridges for openings due to maritime traffic, with 3,600 to 4,000 openings per year, says Jim Richter, Amtrak’s director of bridges and structures.
Once completed, the new bridge will allow Amtrak to increase speed on and near the bridge and minimize delays on a route that serves as a key link for passenger- and freight-rail service between New York City and Boston. Construction began in March 2010. In early September, Amtrak shifted all traffic from the old bridge to the new structure, taking the old one out of service. Trains are sharing one track over the new bridge until the second track is ready for use sometime this month. Amtrak is continuing to open and close the old bridge until it’s dismantled and removed next spring.
“One of the big changes with the new bridge is that the channel is more than twice as wide for marine users, plus we’re gaining a little vertical clearance,” says Richter. “We did a lot of hydrologic studies to figure out the optimum width, and were able to incorporate that into the new design.”
Another key difference is that the old bridge is a rolling lift bascule structure, while the new one is a “fixed trunnion bascule bridge,” which makes it easier for the bridge to open on an electrified railroad with overhead catenary, he says.
The three-year, $140 million Niantic River structure is one of largest bridge projects in recent Amtrak history, says project manager Peter Finch. Since switching operation to the new bridge in September, Amtrak has increased train speed over the bridge by 15 mph.
“We are running on the new bridge with single track,” says Finch. “We’re moving 60 mph, and once we get the second track in service and we see how things behave, we might try [operating trains] up to 70 mph to see how it works. The track geometry is good for that.”
Because of its Long Island Sound location at Niantic Bay, the bridge replacement required the closing of a popular public beach for the past three summers. As a result, Amtrak needed to maintain extensive discussions with the communities involved throughout the process, which included rebuilding the beach area.
“The whole public interface is something that I would say is unprecedented with any project we’ve dealt with here at Amtrak,” says Richter.
Adds Finch: “We had to do a lot of community outreach with the stakeholders to make sure we were not negatively impacting their livelihood.”
MTA Metro-North Railroad’s Harlem River lift bridge is crucial to dail passenger-rail service, too. It accommodates all the railroad’s trains heading into and out of Manhattan — about 754 on a typical weekday. Built in the early 1950s, the bridge is about 4.5 miles north of Grand Central Terminal in New York City.
Later this fall, Metro-North plans to award a construction contract for a two-year project to replace the 128 main cables and 16 auxiliary cables needed to raise the bridge, says Ron Bottacari, Metro-North’s director of tunnels, bridges and track. [Editor’s note: Interviews for this article occurred before Hurricane Sandy struck the East Coast in late October. As of press time, Metro-North officials were assessing damage to the railroad’s infrastructure.]
“They are the original ropes, are exposed to the weather every day and are starting to show signs of corrosion,” he says.
The bridge has parallel lift spans that operate independently. Each has two tracks. Steel towers at each bridge end contain the machinery necessary to lift spans. Metro-North plans to replace the bridge’s electrical control system, install a new power supply system, computerize original circuit boards in the control room and rehabilitate the elevator that runs from the track level to the bridge operator’s room.
The Harlem River is a navigable waterway and under the oversight of the U.S. Coast Guard. As much work as possible is being scheduled during a six-month outage planned by the Coast Guard, which means the bridge will not have to be opened on demand, Bottacari says. Temporary scaffolding, from which crews will install the new cable, will be built above the track so trains can pass underneath. Track outages will be scheduled to minimize impact on riders, he says.
Other major Metro-North bridge projects to be awarded this year include replacement of an overhead bridge in Poughkeepsie, N.Y., as well as a four-span bridge that crosses the Croton River on the Hudson Line.
Attention to bridges likely will increase in the coming years because of a new Federal Railroad Administration mandate on railroads to implement bridge management systems requiring annual bridge inspections and inventories of bridge repair work, he believes.
While many railroads’ major bridge projects involve ceutry-old structures, their original design and construction have stood the test of time, railroad bridge experts say.
“I always applaud the original engineers on the railroad bridges,” says Bottacari. “They were the NASA engineers of their day — the best minds that there were. The design of those old bridges was exceptional in the detail that went into their construction.”
With today’s modern technology and design, improved construction methods and stronger concrete and steel products, the rail bridges being built now should last just as long — if not longer.