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About 8 mi. of new rail is being laid for St. Louis' MetroLink light-rail system. The $676 million extension is running from downtown St. Louis to southwest suburban Shrewsbury. The project involves five general contractors. Major issues included relocating utilities lines, connecting the extension to the existing system and keeping the public informed.
From Forest Park to Shrewsbury, crews are excavating earth, laying tracks and building new rail stations for MetroLink's Cross County extension project - 8 mi. of new light-rail line that will connect the inner-ring suburbs of St. Louis.
Initial phases have required all five of the project's general contractors to relocate dozens of utilities immediately in the track's path.
"One of our biggest challenges is taking this extension through some of the most mature neighborhoods in St. Louis," said Ed Jackson, project director with Tarlton Corp., the St. Louis contractor in charge of building the first 1.6 mi. of the line. "We've encountered every conceivable utility known to man."
Crews have coordinated more than 900 utility relocations that support water, sewer, electricity, gas and cable television, said Cathie Farroll, project communications director for Metro, the St. Louis-based mass-transit agency.
The corridor along Forest Park Parkway - which the extension follows for just less than half of its path - is the oldest utility corridor in St. Louis, Farroll said. In some places, the aging utilities were so brittle that the use of heavy excavation equipment would likely have severely damaged them.
Tarlton crews used hydrovac excavation - removing surrounding earth by spraying it with water, then removing it with a vacuum - in sensitive areas to avoid severing critical lines.
The coordination of utility relocations has been under way since the design process of the project started in July 1999.
Actual utility work and excavation for the tracks began in spring 2003 with most civil construction wrapping up by the end of this year. Track installation has already begin in places and is expected to be finished in December, with overhead catenary systems and signals to follow. The last portion of the project includes station finishes and landscaping. The entire project will be complete and ready for passenger service by September or October 2006.
Installation of tracks is expected to be finished in December, with overhead catenary systems and signals to follow. The last portion of the project includes station finishes and landscaping. The entire project will be complete and ready for passenger service by September or October 2006.
Connecting Communities
The Metro-Link Cross County project is the latest of several projects that have incrementally extended the 38-mi. MetroLink line serving the St. Louis metropolitan region.
The 8-mi. extension connects to the existing line at Forest Park and travels in a dog-leg configuration through seven communities: the city of St. Louis, University City, Clayton, Richmond Heights, Brentwood, Maplewood and Shrewsbury. The extension follows Forest Park Parkway west until it reaches Clayton, then it takes over the former Terminal Railroad freight line where it travels south.
The original 17-mi. line from Lambert-St. Louis International Airport to East St. Louis, Ill., was built in 1993. A 17-mi. addition from East St. Louis to Belleville, Ill., was constructed in 2001, and there was a 4-mi. extension from Belleville to Scott Air Force Base in 2003.
The current extension, a $676 million project, is the first in Missouri since the original system was built.
The project is divided into five "facilities" contracts, each overseen by a general contractor. Four contractors from St. Louis - Tarlton Corp., McCarthy, Fred Weber Inc. (which is overseeing two facilities contracts) and KCI Construction Co. - are performing civil work and station construction.
L.K. Comstock and Co. Inc. of Farmingdale, N.Y., a subsidiary of New York's RailWorks Corp., is the project's transit systems coordinator in charge of laying tracks and installing traction power, signals and communications systems.
Each facilities contract was created in response to geography and size, Farroll said. Each was deliberately kept under $100 million to encourage participation of hometown firms.
"We wanted the local construction firms to bid, and we didn't want to tie up all their bonding capacity," Farroll added.
Tying In
Tarlton is the only contractor to schedule work amidst the exiting MetroLink line. The start of the extension ties in at Forest Park, where crews have had to work around train arrivals every few minutes while performing partial demolition of the existing station, building retaining walls for new tracks and constructing a new center platform at the existing station.
Further along the line, Tarlton crews have been granted weekend shutdowns of major roadways during critical portions of construction of the underground Skinker Station. The cut-and-cover construction is taking place under the Skinker Boulevard and Forest Park Parkway intersection - one of St. Louis' busiest.
Crews have installed temporary bridges and roadway decks to accommodate excavation and construction of the below-grade facility, a "highly sequenced and scheduled operation," said Tarlton's Jackson.
Adding to the stress of construction amidst a heavily trafficked area was the discovery of rock during excavation at elevations much higher - 7 ft. higher in places - than preliminary borings had indicated. Unable to blast in the sensitive and populated location, crews used 10,000-lb. pneumatic hammers to break up the rock, working 12-hour days, seven days a week, Jackson said.
Another challenging section of the project is McCarthy's "Facilities 2" contract: 1.32 mi. of cut-and-cover tunnel construction and two below-grade stations. For tunnel construction, crews shored up the sides of the route and then excavated to 45 ft. below grade, removing approximately 350,000 cu. yds. of material.
The tunnel was built with a 2-ft.-thick concrete base mat, 2-ft.-thick cast-in-place concrete walls and a precast tunnel top.
The top was cast offsite in 586 pieces, each piece weighing approximately 17 tons, said Jon Jacobsmeyer, McCarthy's senior project manager. Placement of the semicircular pieces, each measuring 35 ft. long by 8.5 ft. wide, closely followed incremental construction of the tunnel itself.
McCarthy's value-engineering efforts trimmed an estimated 60 days off the 26-month construction schedule, Jacobsmeyer said. Original designs called for an entire cast-in-place tunnel structure, but a re-evaluation of the plan proved that a combination cast-in-place and precast tunnel could be built more quickly and less expensively, Jacobsmeyer added.
He said additional efficiencies were found during construction of the Big Bend station, where McCarthy crews realized $1 million in savings and shaved six months from the schedule by using a soldier pile and lagging shoring system instead of the originally designed secant pile system.
Once civil work on each line is complete, L.K. Comstock crews take over, laying track, placing ballast and installing overhead systems and signals.
Rail arrives at the site in 80 ft. sections and is then welded together in 1,000- to 1,400-ft. sections and put in place, said George King, Metro's track construction resident engineer. Granite ballast - 70,000 tons to complete the entire extension - is brought in and tamped into place.
Approximately 24,000 tons of concrete ties, each weighing 600 lbs., complete the track work. Installation of poles and overhead lines that form the catenary system closely follow track installation, and the signals come next.
Keeping in Touch
Because the Cross County MetroLink extension is so close to neighboring businesses and residences, Metro has worked to keep the public informed about the extension's progress.
"We looked at the construction process as the start of a long-term relationship with the business owners and residents," Farroll said.
She said public meetings were held in each neighborhood during the planning process to gather suggestions for station designs, and the county has sent notices to neighbors to alert them of potentially disruptive activities.
"We've gone a long way in maintaining their confidence," Farroll added. "We're going to be neighbors for many years."
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