Two of the half-dozen cranes that Lunda moved in for the bridge removal and construction phases of the project. Because of the strong demand on the overpass, bridge removal and construction was carefully staged to keep traffic flowing across the freeway.
Bridge crews are on schedule to complete a series of three new bridges along a 20 mi. (32 km) stretch of I35, a high volume freeway linking the Twin Cities of St. Paul/Minneapolis metro region north to the city of Duluth, a busy international shipping port and tourism destination, and south to the Texas coastline.
Located in the cities of Lino Lakes, Forest Lake and North Branch, just north of the Twin Cities metro area, all three are in various stages of progress. The bridges will be constructed for nearly $31 million.
Lunda Construction out of Black River Falls, Wis., is the primary contractor for the Lino Lakes and North Branch bridges. Robert R. Schroeder Construction, Glenwood, Minn., is building the Forest Lake bridge.
The bridges in North Branch and Lino Lakes are rebuilds while the Forest Lake bridge is a new structure.
Geographically, the majority of the business, commerce and residential areas of Forest Lake and North Branch lie on the east side of the freeway. The overpass at Lino Lakes and its immediate neighbor to the west, Centerville, links those residents to Hugo on the east side of the freeway.
And, it is an important interchange for daily commuters from all three communities heading to work in the Twin Cities.
Continued residential, retail and commercial growth spilling over to the west side of the freeway in Forest Lake and North Branch quickly made those bridges obsolete in terms of traffic capacity and safety which drove the planning to replace them, officials said.
At the Hugo, Lino Lakes and Centerville overpass and interchange, three growing communities also made a re-design and new construction necessary.
At $13 million, the North Branch bridge is undergoing the most extensive construction and will be the first of the bridges to be completed. On schedule to open for traffic in November, it is replacing a two lane bridge with a four lane concrete girder structure with turn lanes and sidewalks on both sides.
Though nearly the same length of the old bridge, 200 ft. (320 m), the new bridge will be more than twice as wide at 115 ft. (184 m). It will feature two through lanes in each direction, turn lanes and sidewalks on both sides of the bridge; unlike the previous bridge which carried one through lane in each direction. Concrete girders spanning 100 ft. (160 m) on each side of the freeway carry the deck.
Significant road work and signal improvements also are a major part of construction for this project.
And, similar to other freeway over passes built in recent years, the new bridge also will feature a field stone façade, masking the concrete beam structure behind it and making it more architecturally pleasing to the community and passing drivers.
According to Julie Dresel, city engineer of North Branch, the bridge there was long over due for replacement because of the huge increase in additional traffic.
“We were primarily concerned with congestion and pedestrian safety,” Dresel said. “The bridge was essentially under capacity before we had any development on the west side of the freeway.”
The ADT numbers attest to the capacity problems. An ADT of 13,700 in 1998 jumped to 21,000 in 2010. Discussions began in 1997 to upgrade the bridge, Dresel noted.
Despite some lost days due to the cold winter and a wet summer and with the help of Arnt Construction, Hugo, Minn., and Knife River Construction, Sauk Rapids, Minn., the bridge is on schedule said Bruce Bartelt, Lunda project superintendent.
“All in all, its gone well. We wanted to get to the point where we had the wear course down by this fall and it was placed in early October,” Bartelt added.
Lunda mobilized several American cranes for the bridge work, Bartelt said.
Similar to other bridge replacement projects in the state and around the nation, Lunda bridge workers built the new bridge in two stages to maintain traffic. When crews completed the first half of the new bridge, traffic was switched over to that structure, and then the old bridge was removed to make way for the second stage of construction.
“This bridge was long overdue for replacement,” Bartelt said.“It’s a big, busy interchange and the traffic volumes are high and one of the challenges.”
Though “the staged construction is always a challenge,” Bartelt noted, the removal of the old bridge required a different strategy than usual because of the demanding use of the TH 95 crossing.
TH 95 is the lifeline for shoppers between the east and west sides of the freeway and for those coming in from the surrounding communities, according to city officials.
“Unlike a number of bridges that are removed over a weekend and traffic is sent up and over the ramps or a detour is established and the freeway is shut down, the city of North Branch needed to maintain east and westbound TH 95,” Bartelt explained. “So, we took it down over the course of several week day nights with lane closures instead of shutting down the freeway completely this past summer.”
In contrast, Bartelt added, crews removed the Lino Lakes bridge, which was similar in size to the North Branch bridge, in less than 24 hours.
“We started the removal at Lino Lakes around 10 pm on a Friday night in September. We had the deck gone, sub-structure gone, rubble cleaned off, roadway swept cleaned and all four lanes of I35 open by the next day at 6 pm,” Bartelt said.
For the concrete girder beam placement though, the city of North Branch did allow the freeway to be shut down, Bartelt said.
Beam placement for the first stage of the bridge occurred last winter. By 8 p.m. on a cold, February night, traffic was closed off at the North Branch exits and channeled up and over the ramps, Bartelt said.
“We set 10 girders, five per span that night,” said Bartelt. “They [city officials] allowed us to go up and over the ramps. We had state troopers below and North Branch police on top for traffic control. And, we had the freeway open by 5 am the following morning.”
Lunda workers did the same in July for the second stage of the bridge. However, beam setting required an extra night because the second stage of the bridge construction was wider than the first and required a total of 24 girders, Bartelt explained.
Bridge workers covered more than 8,200 sq. ft. (763 sq m) of the bridge with a fieldstone facade. The bridge also required more than 100,000 lbs. (45,000 kg) of reinforcement bar.
Recycling materials and erosion control also played into the picture of this project, Bartelt added.
“We lifted the pre-stressed concrete girders from the old bridge, swung them over behind the abutments and dragged them out for processing with a muncher,” Bartelt said. “Most of the old bridge material came back to the site as Class V for the road bed.”
With a nearby creek and a ponding area, erosion control was also a priority for Lunda Construction.
“The contract alone for just erosion control was just shy of $200,000. There were some sensitive areas of water in the project area that required protection and we had to have turf establishment,” Bartelt said.
Along with the bridge construction, Arnt Construction brought in more than two dozen pieces of heavy equipment including Cat backhoes, dozers, rollers, graders and scrapers for the excavation, pipe and grading operations.
Like the Lunda bridge crews, road workers for Arnt Construction, toiling under moving traffic with multiple phases also was a challenge, Nick Arnt of Arnt Construction said.
However, installing water and sewer pipe at a variety of elevations presented a challenge on its own.
“On County Rd 68, we had to install sanitary sewer 18 foot deep, 20 inch water main and storm sewer 12 feet deep while maintaining traffic,” Arnt explained. “In some sections of the road, the elevation changed by as much as 9 feet.”
Estimated quantities for this phase include 136,000 cu. yds. (104,000 cu m) of soil excavation, 20,400 cu. yds. (15,600 cu m) of aggregate base, more than 2,000 ft. (610 m) of water main and more than 11,000 ft. (3,500 m) of sewer pipe.
Bridge crews from Robert R. Schroeder Construction in Forest Lake, 15 mi. (24 km) south of North Branch are also making good progress and on schedule with the new bridge there. The $7 million overpass will help alleviate traffic congestion on the existing overpass just about one mi. (1.6 km) further north of the new bridge, according to Jane Kresbach, design coordinator for Washington County, the lead agency for the project.
The Forest Lake bridge will be a pre-stressed concrete beam structure carrying two lanes of traffic and featuring an architectural concrete texture on its façade, retaining walls and pillars and ornamental railing that incorporates the city of Forest Lake sail motif.
Seven mi. (11 km) south of Forest Lake, Lunda bridge crews just started work on the second stage of the $10.7 million Lino Lakes bridge. When this project is completed, commuters hitting the freeway from the towns of Lino Lakes and Centerville on the west side of the freeway and those from Hugo on the east side will see completely different geometrics from the original interchange.
Along with the traditional four on and off ramps at the freeway, two loops will be added. According to a sketch of the new interchange, the loops, located on the north side of the overpass, will eliminate left turn movements.
For drivers accessing I35 southbound and crossing the bridge from Hugo from the east, they will turn right on the west side of the bridge and loop into southbound I35. For drivers exiting northbound I35 and heading to the west, they will loop around and merge with westbound traffic towards the communities of Lino Lakes and Centerville.
Traditional on and off ramps also will be built for drivers entering or exiting I35 at this interchange.
Similar to the North Branch bridge project, the new bridge in Lino Lakes will carry four lanes of traffic and dedicated turn lanes to meet the increasing demand in traffic for that crossing.
The bridge will be 250 ft. (76 m) long, 116 ft. (35 m) wide. Sixteen 138 ft. (42 m) and eleven 109 ft. (33 m) will carry the deck.
With the North Branch and Forest Lake bridges nearing completion, residents and visitors in those communities will soon have a much easier path to negotiate between the east and west sides of I35.
With a June 2011 completion date, residents in the communities of Hugo, Lino Lakes and Centerville will need to continue to rely on their patience. However, the new and unique renovations to the over pass and interchange will greatly improve traffic flow and no doubt seem to make the wait worthwhile.