Though relatively short in length, a county bridge project in St. Paul, Minn., is long in duration because bridge crews worked above an average of 110 trains a day rolling beneath the bridge deck. Spanning nine sets of tracks, work stoppages on the bridge were part of the daily work schedule for work crews when trains rumbled through.
Further complicating the construction schedule, the tracks, owned by three separate railroad companies, fan out to a huge switching yard. Many times, bridge crews paused again during track switching operations.
What typically would be completed in nine months or less was stretched out to a two year project because the timeline was dependent on the railroad schedules, said Erin Laberee, Ramsey County project engineer.
Edward Kraemer and Sons Inc. took on the $11.7 million project. Founded in 1911 by Edward Kraemer as a small carpentry business in Plain, Wis., the company quickly grew.
It now has regional offices in Wisconsin, Minnesota and Colorado. The company builds transportation, heavy industrial, water resources, commercial and marine projects throughout the country.
Warner Road and the bridge are part of the Ramsey County road network in St. Paul.
Located just southeast of downtown St. Paul, the Warner Road bridge sits on a flood plain between the Mississippi River on one side and a nearby, 100 ft. (30.5 m) bluff on the other. It carries eastbound traffic coming out of the St. Paul business and entertainment district over the railroad tracks.
With an ADT of 17,900, Warner Road is a key trucking route and is a direct link for residents of several suburban communities into and out of downtown St. Paul.
Just less than one mi. (1.6 km) east of the bridge, Warner Road connects to Minnesota TH 61 and I 94, both carrying approximately 100,000 motorists daily through this part of St. Paul.
On a national scale, Warner Road forms a short segment of the Great River Road made up of many different highways that closely parallel the Mississippi River from its headwaters in Itasca, Minn., south to the Gulf of Mexico.
Located very close to the bridge and nestled just outside the switching yard is a Cemstone concrete plant and metal recycling company which added heavy volumes of truck traffic through the construction site.
The regional sewage treatment plant serving St. Paul and Minneapolis is located farther south of the bridge. Childs Road shooting off mainline Warner Road just north of the bridge serves as the local access to these facilities.
A structural deficiency rating spurred the reconstruction of this bridge which was built in 1942. Its westbound partner was reconstructed in 1977 and is in much better condition according to Leberee.
Even before construction began, the system of railroads played a huge role in the design features and legal issues in putting the project out to bid, Leberee noted.
“The railroads wanted to ensure future railroad expansion would not be limited by the new bridge piers,” Leberee said. At the same time, “the existing locations of the westbound bridge and the Childs Road bridge were taken into consideration as well when designing the eastbound bridge to allow for future railroad expansion.”
Nailing down the language on the necessary agreements and approvals between the county and multiple railroads required a huge amount of advance work on the legal side of the project.
“Regular meetings between the county and the railroads were held well in a year advance just to receive approvals for the agreements to allow the county to work within the railroads’ right of ways,” Leberee said.
Funding restrictions affected the type of bridge to be built.
“Concrete beam or long span steel were both considered and the decision ultimately came down to cost because long span steel was not feasible from a funding standpoint,” Leberee said.
“So far we’ve been pleased with construction. The project remains on schedule and budget. We’ve encountered some minor issues and changes to the construction contract, but that is to be expected,” Laberee said.
“The perception from the general public has been that construction is occurring slower than normal when compared to a smaller bridge like a freeway overpass. Once we explain the constraints of the project and the issues with the railroads, folks have been understanding of the timeline to get the bridge completed,” Laberee added.
Steve Kaldenbach, Edward Kraemer and Sons construction superintendent concurred.
“Construction has been going well as much as can be expected with the railroad interruptions. We do a lot of work with the railroads so we know how that game goes. You just have to work closely with the railroads,” Kaldenbach said.
The contractor is shooting to open the bridge to traffic on September 25th, with minor work and landscaping continuing into the fall.
When completed, the 842 ft. (256.6 m) long bridge will accommodate two 12 ft. (3.7 m) travel lanes, two 4 ft. (1.2 m) shoulders and a 12 ft. (3.7 m) wide pedestrian trail.
In addition to the roadway bridge, two grade separated trail bridges were constructed as part of the project to replace at grade trail crossings at the Childs Road on and off ramps. The trail bridges are 678 ft. (206.6 m) and 352 ft. (107.3) long.
Construction on the bridge began in the fall of 2013 with the demolition of the super structure and piers. In the contractor’s favor, traffic crews routed traffic one lane each direction to its westbound partner to separate construction crews from the road traffic.
So, on the bridge, “traffic was not an issue. It was a little inconvenient on the other bridge for the traveling public because during rush hour it’s pretty busy. Other than that, Warner Road is a commuter road. Heavy in the morning, heavy in the afternoon. During the day, it’s pretty quiet,” Kaldenbach said.
With all the construction going on in the St. Paul area, the Cemstone plant is busy with truck traffic while the recycling and treatment plant generate much less.
Again working in the contactor’s favor, Childs Road was the only access to all three operations, with the Cemstone plant bringing in most of the traffic. So, traffic was pretty much manageable, Kaldenbach said.
“There are a lot of concrete trucks coming and going and we had cranes in their yard. Cemstone has been really good to work with. As long as we communicated, traffic was not an issue,” Kaldenbach said.
Building a bridge over nine sets of railroad tracks is quite complicated, Kaldenbach said and required an on-going strategy and changes in demolition and construction phasing.
Crews removed as much of the old bridge that they could without interference from the railroad traffic. The piers and the super structure not sitting over the tracks came down first. When there was a break in railroad traffic, they would whittle away at the demolition over the tracks.
Bridge crews started construction on the new piers and super structure while demolition continued on the old.
On hand during the demolition phase of the work were a Cat backhoe 336E, a Cat backhoe 3300 and a Liebher backhoe 924. Later into the construction schedule a John Deere backhoe 200C and a Volvo dozer arrived at the site.
The duration and schedule of the project are totally a function of the railroad schedules.
“We tried to go aft.er as much work that we could. We removed the east and westbound approaches. We started working on the new construction while we were still doing removals on other parts of the bridge,” Kaldenbach said.
“Just getting access in there; you had very small windows of time,” Kaldenbach continued. “Some days, we might get an hour, on other days, sometimes two hours.”
At the same time, track switching operations would halt construction over the tracks.
“So, was it inconvenient, it was. It’s hard to plan your work operations around not knowing each day what kind of traffic you would run into,” Kaldenbach acknowledged.
Some construction operations required larger blocks of time. With the cooperation of the separate railroads, Edward Kraemer and Sons crews managed to take more significant time on just two occasions.
The first occurred during Memorial Day weekend of 2014. As piers outside the railroad tracks began rising above ground, Kaldenbach arranged with the railroads to remove part of the old bridge spanning the tracks.
And on an unseasonably mild weekend for Minnesota last January with temperatures in the upper 30s, bridge crews set girders over the main span.
For the girder picks, the contractor brought in a Terex HC 125 crane and an American 9310 crane. Supporting the pick operations were a couple of JLG lifts.
“Most of the pre-cast girders we tried to do in two crane picks because you have better control over the movement of the girders. Lifting operations really went well. We didn’t have any snags. We did a lot girder erection over the winter,” Kaldenbach said.
Girder erection took about six weeks while girder removal was spread out over a few months, Kaldenbach said.
Bridge crews placed a total of 54 concrete girders on the bridge with the largest weighing 94.5 ton (85.7 t).
Working around the schedules of the three railroads was the biggest challenge for construction crews. Other than that, “this is really not that complicated of a project; it’s pretty straight forward,” Kaldenbach said.
This is not to say that there were not other minor issues construction crews faced building the Warner Road Bridge.
The results of a cold and snow laden winter in 2014 was one of them. It was not the snow or cold though; it was what followed that slowed construction a bit.
When spring finally arrived, it brought some minor flooding from a swollen Mississippi River to the construction site and Childs Road.
“We probably had about a foot of water here on Childs Road. So, it was a little bit tough to get down here but we kept working. It was kind of a struggle for about a week maybe a week and a half because of that water,” Kaldenbach said.
Construction crews ran into another water issue on the east end of the bridge. Though not a major problem, a water table higher than anticipated had dewatering pumps running longer, yet did not cause any delay to the schedule, Kaldenbach said.
The east end of the bridge also presented a challenge for the girder picks between the east abutment and the next pier. According to Kaldenbach, the regional sanitation sewer treatment plant has a pump house there and an old sewer line to the plant runs beneath this span.
“Because it’s so shallow and so old, they were worried about the condition of the pipe and how much load it could take. There is a 30 ft. (9.1 m) exclusion zone where we cannot work. We could not park any equipment there. No truck, no cranes, nothing,” Kaldenbach said.
So, that was a challenge Kaldenbach said in determining the best positions to set the cranes in.
Most of the bridge is now complete. Remaining work includes placing the rest of the bituminous paving, pouring the concrete barrier, finishing the approach work, installing the lighting and ornamental railing need to be completed.
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