A Komatsu backhoe backfills a ditch containing a pair of relocated DistricEnergy hot water pipe along Fourth Street in downtown St. Paul.
Crews recently completed advanced underground utility relocations in downtown St. Paul in preparation for the start of construction this March of an 11 mile Light Rail Transit (LRT) system connecting the downtowns of St. Paul and Minneapolis.
And good news for the local, state and federal agencies kicking in funding for the project, all of the construction contracts have been awarded and came in at $34 million below the original estimate. However, the $957 million project is still expected to be the largest public works project in the state of Minnesota.
Walsh Construction, Ames-McCrossan Joint Venture, Aldridge-Collisys Joint Venture and PCL Construction Services, all Midwest-based companies, will build the system.
The Metropolitan Council, a seven-county regional governmental body in the Twin Cities, will own and operate the track system.
Once completed, the pair of LRT tracks will run primarily along all of University Avenue, a major, four lane arterial located in the city of St. Paul. At the east and west ends of University Avenue the tracks will split off onto other arterial routes into the downtowns of St. Paul and Minneapolis. In St. Paul, the terminous will be in front of the historic Union Depot train station.
In Minneapolis, the tracks will connect with the Hiawatha LRT line just east of the Metrodome and travel the last mile over Hiawatha track and terminate at the new Target Field Station and home of the Minnesota Twins.
The LRT will also connect to the Northstar commuter line at the Target Field Station. The Northstar line carries passengers between Minneapolis and Big Lake, 40 mi. (64 km) to the north.
Along the way, structural modifications will be made to three bridges on the route to increase their load capacities to safely carry the added weight of the trains. Included in this list is the Washington Avenue Bridge crossing the Mississippi River and connecting the East and West bank campuses of the University of Minnesota. Over several hundred feet long, it is the largest of the bridges and the most expensive, $56 million to modify.
Additionally, the vacant Bremer Bank Building in downtown St. Paul will be demolished to make room for the pair of tracks to make two partial, 45 degree turns on there way to and from the Union Depot.
Special features to this project include floating slab treatments approximately 1,450 ft (442 m ) along Washington Avenue on the East Bank campus of the University of Minnesota to mitigate train-caused vibrations that may affect nearby college laboratories.
Along with the construction of the tracks, its power system, 18 stations and conversion of a large, vacant building once owned by Gillette Company on the outer limits of downtown St. Paul to an operations and maintenance facility, construction will also include an entire street reconstruction in the right of way. This will include new pavement, signal system, curb and gutter, sidewalks and streetscape.
Green energy savings include LED lighting, using recyclable materials and innovative mechanical strategies and insulation practices.
Metropolitan Council documents add that the conversion of the old Gillette building will save the cost of producing and delivering more than 12 million lbs. (5.4 million kg) of concrete and thousands of pounds of steel. Also, about 50,000 ln. ft. (15,250 m) of piling supporting the existing floor and roof-support columns will remain in place.
Eventually, 12,300 tons (11,070 t) of steel will be laid for the pair of tracks, of which 30 percent will be recycled steel, 2,540 ton (2,286 t) of structural steel wil be placed with 85 percent of it coming from recycled steel, copper for the station roofs and LED lighting.
Also a stormwater rock infiltration system will be installed under the curbs to filter out pollution before it is absorbed by the underground soil.
According to Metropolitan Council documents, the project will create 800 direct construction and management jobs annually over the length of the project along with hundreds of more spinoff jobs in the construction industry.
Work on the twin rails began just north of the St. Paul downtown business district this past September. Beginning this March, however, construction will kick into full gear at the St. Paul and Minneapolis border and work east toward downtown St. Paul. All light rail will work will be completed by 2014.
However, before workers and equipment begin laying the first rail, several underground utilities had to be moved out from the future tracks in downtown St. Paul so utility workers in the future would be able to access them for maintenance or possible repairs without interrupting train service.
Public utilities that were moved included city storm and sanitary sewer systems and city water mains. Also, District Energy, which cools and heats most of downtown St. Paul had to relocate its piping system.
Private utilities moved included Xcel electric and gas lines, and Comcast, Verizon, Qwest and Time Warner cables.
Most of the utility moves to date have been centered along nearly a mile long length of Fourth Street in downtown St. Paul. Dozens of Komatsu and John Deere backhoes, dozers and bobcats and Grove cranes moved onto Fourth Street in October, 2009 for the start of utility relocations.
Kevin Ryan, manager of transitways construction for the Central Corridor LRT Project added that work has been going as well as expected.
“Whenever you open a street in a downtown area, you are going to encounter unknown utilities,” Ryan remarked. “We were sure that would happen. Nothing unique. It’s been a typical, urban street excavation.”
District Energy St. Paul and District Cooling St. Paul, headquartered in downtown St. Paul along with its plant, had some of the most extensive digging relocation work along Fourth Street. Crews relocated approximately 4,800 ft. (1,464 m) of hot water pipe (HWP) and 1,800 ft. (549 ) of chilled water pipe (CHWP) to make room for the LRT tracks.
According to Nina Axelson, Director of Public Affairs for District Energy, the pair of (HWP) operated by District Energy and relocated ranged in size from 2/5 in. (5/13 cm) to 20/25 in. (51/64 cm ) in diameter. The (CHWP) ranged in size from 12 in. (30 cm) to 18 in. (46 cm) in diameter.
“District Energy and District Cooling work was performed under the Metropolitan Council’s contract and construction done by the Met Council’s contractors and subcontractors,” Axelson explained. “They worked closely with the Met Council and its contractor to resolve any construction related challenges.”
“Our hot water piping requires pre-heating before backfilling to allow for adequate pipe expansion, which required the contractor to be able to leave a trench open for a period of time while maintaining traffic on cross streets,” Axelson explained.
“To maintain heating and cooling service for the company’s customers, work was done during the off season for each facility,” Axelson explained. “The HWP was moved in the summer while the CHWP was moved in the winter.”
When necessary, District Energy provided temporary piping to its customers requiring year round service and the company provided oversight of work related to the system.
“Working together, we were able to design and execute appropriate sequencing modifications in the field to accelerate pipe installation with minimal impacts to our customers,” Axelson noted.
Though much of Fourth Street has been shut down throughout the last year, traffic was routed to other streets without disrupting access to a variety of businesses lining the street according to city of St. Paul officials.
Along with temporary sidewalks and a network of a second story skyway system crossing over Fourth Street, pedestrians have been able to negotiate in and around the busy construction zone.
The skyways, in fact, became a birds eye view for everyday workers and visitors to downtown St. Paul watching the construction.
One second level “sidewalk inspector” remarked that “it’s been fascinating to watch the crews from the utilities work in and around other utilities and at the same time keeping the buildings cool in the summer and warm in the winter without creating a nuisance for vehicular traffic!”
When the LRT is completed, the projected travel time between the two downtowns will be less than 40 minutes and projected daily boardings by 2030 will be 41,000 passengers.
Adjustments to current bus routes will also be made once the LRT is in operation. Some of these changes include reducing the number of bus rides on University Avenue and adding new routes for riders to more easily access the LRT. CEG
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