More than a dozen workers man a Guntert S850 paver and a RexCon Town & Country Placer/Spreader on the way to placing over a mile of 9 in. (23 cm) unbonded concrete in a day.
The Minnesota Department of Transportation (MnDOT) and its contractor, PCI Construction Services Inc. are making good time putting down the final strip of concrete for an un-bonded concrete overlay project on I-35E just outside of St. Paul, Minn. This project, one of several road improvements on the interstate over the years, centers on one of the busier sections of I-35E running north out of White Bear Lake, a suburban lake community located 15 mi. (24 km) north of St. Paul.
PCI came in with a low bid of $20.4 million to replace the badly deteriorating bituminous surface on a four lane section of the interstate stretching between White Bear Lake to its connection with I35W, 10 mi. (16 km) to the north, where both freeways merge into one as I-35. A north south interstate, I-35 connects the northern Minnesota international port city of Duluth to Laredo, Texas, 1,558 mi. (2,500 km) to the south.
Though expected to be completed during the 2011 construction season, the project finish date was delayed because of a budget impasse in the Minnesota State Legislature. State offices were closed, workers temporarily laid off and all MnDOT road work interrupted on July 1 of last year for nearly three weeks until the legislature came to a budget agreement later that month.
Despite the fact that PCI had time to complete only the southbound lanes of the freeway last year and basically re-mobilize in early 2012 to finish the northbound lanes, most of the entire project is expected to be completed at press time.
“The project has been going very well considering that we had to split it up over two years,” said Garrett Schreiner, EIT and MnDOT project engineer. “We haven’t had any major issues and the weather has been relatively cooperative. We’re on schedule to finish.”
MnDOT and PCI are shooting to open the entire 10 mi. (16 km) stretch of the project to four lanes later this month to be followed with some turf restoration and guard rail construction continuing through the summer months, Schreiner said.
PCI Construction Services Inc. is a major heavy road and bridge contractor located in Burnsville, Minn., and a major general contractor working in the upper midwest.
With an ADT up to 70,000, this section of I-35E took a beating over the years with the continual road traffic and deteriorating surface winning the battle over road maintenance crews.
When unexpected federal money was set free for Minnesota, MnDOT officials made the best use of the funds by going for a long-term solution instead of a shorter term fix for the aging pavement.
“We had initially scoped this job out to be just a mill and overlay. When we heard federal funding was available, our material’s office re-evaluated the job and decided to go for a longer term, 25 to 30 year fix with the un-bonded overlay,” said Jennie Read, PE and North Area MnDOT district engineer.
“And it was a very quick timeline that we had,” Read emphasized. “We received word that this money would be available in October, 2010 and we had to have signed plans by February, 2011.”
Except in areas below many of the bridges crossing the route, the end result, Schreiner said, will be a freeway 6 in. (15 cm) higher than the original surface along with corrections made to the super elevation and the cross slope.
Under many of the bridges that cross the project area, 10.5 in. (25 cm) of un-bonded concrete will be placed with more narrow bands of sub-base to lower the pavement section in these portions of the road because of bridge height limitations Schreiner explained.
Many factors come into play to determine the best options in replacing an aging highway surface. According to the MnDOT Materials Lab, one major factor is the design features of the in-place roadway.
MnDOT Materials Lab staff cite the design differences of I-94 cutting through the urban centers of St. Paul and Minneapolis and now under going a more traditional mill and asphalt overlay versus the I-35E road work.
Along this urban stretch of I-94, “there are a lot of bridges, drainage structures and barriers that would make an un-bonded overlay impractical,” according to the MnDOT Materials Lab.
Though asphalt overlays last less than 10 years, short of removing the in-place pavement and starting over, asphalt overlays are the only practical solution for highways designed and constructed for inner city use, MnDOT Materials Lab staff said.
On the other hand, the I-35E freeway is located in a rural area with few bridges, no curb and gutter and no drainage issues. Because the design and construction of the rural interstate is much more basic, the un-bonded overlay is more easily placed and will last up to 30 years, added the Materials Lab.
Within the work zone, traffic has been cut down from two lanes to one lane in each direction to make for traffic free work space on the lanes under construction.
Though traffic slow-downs and back-ups are occurring, there have been very few complaints from the traveling public according to TK Kramascz, communications director for the MnDOT Office of Public Affairs. He gives credit to PCI and its sub-contractors along with MnDOT construction staff for making his job easier navigating through the sometimes hostile world of dirt, noise and traffic delay complaints that are part of major road construction.
“What I care about most is when the contractor does work according to schedule and this contractor is hitting its targets.
“Having said that, nobody likes construction and they don’t like ramps closed to and from the mainline,” said Kramascz.
Yet, from a public affairs standpoint, “we’ve had more of the curious type of questions” versus complaints coming into our department, Kramascz added.
Kramascz and his staff rely heavily on the local media and their own web site to update the public.
“As soon as we get information we put it out to the media and through our email and even twitter sometimes. So, we have a whole arsenal of methods to get information out,” Kramascz remarked. “It starts with good quality project management and good work by the inspectors working with the contractor."
“The biggest issue is dealing with the traffic and minimizing delays because it is such a heavily traveled corridor,” Schreiner said. “We have some plans in place if the delays get too high and we’ve added some ramp meters at the entrances.”
Though there is no dedicated detour route, MnDOT staff did optimize the signals along US Highway 61 which runs parallel to I-35E about 1 mi. (1.6 km) to the east. It was formally the main route to Duluth prior to the construction of the freeway and it is a familiar highway to daily commuters and travelers.
With a peak work force of nearly140 tradesmen and a dozen or so pieces of heavy equipment at any one time, freeway commuters and travelers have seen a lot activity on and even off the construction site.
Once drivers survive the loud and dusty milling part of the project, they can begin to see daily progress because concrete paving equipment can spread more than 1 mi. (1.6 km) of fresh concrete on a daily basis.
“And that’s the beauty of a project like this. While people are stuck in traffic, they can see at least some progress out there.” said Rich Norgard, chief MnDOT inspector for the project.
During on-going concrete paving operations, Norgard estimates 100 trucks drive into and out of the plant site daily to bring concrete to the paving crews. Out on the construction site, concrete crews are now pouring the last several miles of the new northbound lanes.
Manned by a dozen or so workers, the Guntert Paver S850 and RexCon Town and Country Placer/Spreader slowly and methodically crawl forward. They cover 6,000 ln ft. (1,830 km) a day to place 5,000 cu. yds. (3,825 cu yd) of 9 in. (23 cm) thick un-bonded concrete on a strip of roadway 28 ft. (9 m) wide.
A Cat 350 backhoe is the largest excavator on site with several smaller Cat backhoes on hand and scattered throughout the project. Smaller Bobcats are spreading and grading the shoulder areas.
Off site, crews pieced together a portable concrete batch plant just halfway beyond the mid-point of the road work and a short distance from the freeway. There, two huge Cat Dozers are loading sand non-stop onto a conveyor belt of the plant while a Cat grader maintains the access road to the plant area from a local road.
At the entrance to the site, flagging operations help control the heavy mix of concrete trucks arriving and leaving the plant site sharing the same road with local traffic.
Much of the Class VI road base is recycled along with the fly ash used in the batch plant and comes as a byproduct from coal plants throughout the mid-west.
Currently, more than 50 percent of concrete pavement has been placed on the northbound lanes of the interstate while the two new lanes of southbound traffic completed last year carry two way traffic.
As construction begins to wind down later this month, regular drivers along this stretch of I-35E should have their road back to all four lanes and just in time for the summer tourist season. They will only be slightly distracted by the on-going guard rail and turf work through the summer months. CEG