Major four-lane Kansas highway project beats challenges

The city of McPherson lies just east of the center of Kansas, but is dead center of a major construction project.

The four-lane highway project is a new road alignment just west of the original two-lane K-61 Highway. One of the reasons for moving the road from its existing path is to locate it farther away from the railroad tracks in order to meet new environmental standards, and to avoid disruption of the agriculture for the nearby ranchers. Sections of the project called for incorporating the footprint of the old road, but much of the planned construction required purchasing right-of-way rights from farms abutting the new highway.

Bob Bergkamp Construction, Wichita, Kansas won the bid for building an eight-and-a-half-mile section of the new K-61 Highway project.

Bergkamp Construction used a 3-D model of the project to support the GPS-enabled heavy equipment, total stations, and data collectors used throughout the job site. “We took the Kansas Department of Transportation’s CAD files and used Trimble® Terramodel and Trimble Business Center – Heavy Construction Edition office software to convert the files for use on our machines and rovers,” states Justin Howard, field engineer with Bob Bergkamp Construction. “The Trimble software gave us all the job site and surface modeling we needed to establish the road parameters.”

Clearing the necessary 200- to 400-foot wide swath for the new road was a challenge.  “This was one of the bigger clearing jobs we’ve had to do on a highway project,” says Rick Thome, project engineer with Bob Bergkamp Construction. “It took a month to cut through the brush, trees, and heavily-wooded land. We’d clear a section, start the actual road-building process, and then move down onto a new section.”           

After clearing the new roadway swath, the initial push was to establish the bridge berms so that the two bridge contractors could complete the work.  Overpass bridges required pilings be set anywhere from 60- to 200-feet deep, with footings at eight- to 10-feet. Bergkamp Construction needed to build 18 bridge berms that were about 20- to 25-feet above the road grade.

In its road building, Bergkamp Construction used an approximate 50/50 soil mix—which was about a million yards of on-site dirt and a million yards of imported dirt.

“We had to remove the top six inches and rework the bottom six inches, and then put that six inches back before the finish grading,” states Howard. “The dirt was tested to 90 percent density until we reached the top of the fill where it tested for 95 percent density.”

With an understanding that the road is only as good as the subgrade, Bob Bergkamp Construction knew that each lift required precision in the grade. The company used two motor graders and a dozer equipped with Trimble® GCS900 Grade Control Systems with dual GPS. The Trimble systems put the site plan—design surfaces, grades and alignments—right inside the cab and helped the operator achieve the plus or minus a tenth millimeter accuracy that Bergkamp Construction established as their standard.

“The blades have the Trimble® MS990 Smart GPS Antenna which is an integrated GPS antenna and receiver, and we have the Trimble CB430 Control Box, with its very readable screen, even in bright daylight,” Howard states. “We have the technology to reliably achieve grade in one pass.”

For their stretch of the K-61 highway corridor project, Bergkamp Construction used three Trimble® SPS851 Modular GPS Receivers for semi-permanent base station setups to support the grade checking, site measurement and stakeout. The combination radio and GPS receivers were set up on both ends and in the middle to ensure adequate coverage of the entire site.

 “There’s a configuration function in the SPS851 that allows for multiple base points to run off the same continuous calibration,” Howard says. “This saved me at least a couple of days of set up time since each base station didn’t require the time to establish its location base point.”

For Bob Bergkamp Construction, the eight-and-a-half mile K-61 Highway project was one of its longest distance road building projects. At their busiest, they had four crews amounting to around 30 workers at the site. It was also the most GPS-based technology they’ve had on one jobsite. “Having the Trimble technology was a tremendous help and it saved us time and increased production,” Howard notes.

 The company’s foreman was able to walk ahead of the production crew and establish points using the rover. “This is far better than having to pull a hundred feet of tape up a hill to stake it, and then run back down the hill to use an eye level,” Howard says. “Here in Kansas, a light breeze is 20 miles per hour, so that tape would be blowing around.”

Howard continues: “The technology helps cut production time.  Most of the time you don’t need stakes.  The GPS-guided machine will do it for you. We can control the volume of fill with each lift by doing a vertical offset. It has really helped us maintain proper compaction, especially when we needed to transition Type A compaction to the Type AA.  The inspectors are a lot tougher on the Type AA, which is that 18-inch zone at the top.“

Unusually wet weather created schedule challenges, but Bob Bergkamp Construction was able to complete the project on time.  The project was also a bit of a learning curve for several of Bergkamp’s foremen and workers who were initially resistant to using GPS grade control systems.

“Some of our employees were pretty old-school,” Howard says.  “But now that they’ve experienced the Trimble technology they are confirmed believers in using technology. It didn’t take them long to see that once we finish something with the GPS-guided machine, 99.9 percent of the time there is no rework, because when it’s done, it’s done accurately.”

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Jeff Winke is a business and construction writer based in Milwaukee, Wis. He can be reached through www.jeffwinke.com.