Depending on their driving habits, motorists in the state of Missouri have probably been noticing one of two things. Alert drivers are likely seeing construction crews operating cold planer milling machines on highways, removing old shoulders to make way for new. Sleepy or inattentive drivers may not be catching any of the actual construction, but might be experiencing the occasional awakening jolt from the freshly stamped rumble strips that have been added to those new shoulders.
This type of road repair work is very common today throughout the Midwest. In some cases, highway shoulders remain solid enough that rumble strips can be added to the existing asphalt surface. But far more often, thin pavement layers have rendered shoulders susceptible to deterioration. The only option in such situations is to mill the shoulder out and put down new asphalt in its place.
APAC Missouri is one contractor that’s bid its fair share of projects involving the addition of rumble strips to highway shoulders across the state. One of the leading construction groups in the region for more than a century, APAC Missouri operates its own quarries and asphalt plants, in addition to running asphalt paving crews. The company currently employs 120 people out of its Springfield, MO office alone.
“There’s a lot of this construction going on in Missouri right now,” says a spokesperson for APAC Missouri. “We’re removing two-, three- or four-foot sections of shoulder, putting back new mix and then adding rumble strips. We had enough work going on at one point this past summer that we were running nine different milling machines, including those in our fleet and some we rented.”
Renting made sense
One of those rentals came about as the company was preparing to tackle three different milling projects requiring a 4-foot mill in July 2012. Facing a fairly tight production schedule, APAC Missouri connected with the G.W. Van Keppel Company and arranged a 30-day rental of a BOMAG BM1200/30-2 cold planer milling machine.
Powered by a 275-hp Caterpillar diesel engine and featuring a centrally mounted cutting drum for enhanced stability, the BM1200/30-2 offers a 47.2-inch milling width and is capable of milling depths up to 12.6 inches.
“We needed a 4-foot mill in short order, and the availability and price was right, so we went ahead and rented it,” says APAC Missouri.
The primary job for the milling machine involved removing portions of the shoulder — 4 feet wide and 3 inches deep — for 30 total miles along both the northbound and southbound lanes of U.S. Highway 65, between Springfield and Fair Grove, MO. Approximately 10,000 tons of asphalt was to be removed, which the company, in turn, was planning to use for general fill material at another location.
“Our bidding process required us to achieve certain tonnage milestones on a daily basis,” says APAC Missouri. “As it turned out, the machine actually delivered a higher production rate than we had hoped for. We got very consistent production, and were able to complete the whole job in just six days.”
The average milling rate achieved by the milling machine on the Highway 65 job was approximately 90 feet per minute. The machine’s efficiency also enhanced the efforts of the rest of the APAC crew on the jobsite, who followed behind the milling progress with a road widener and two tandem rollers to rebuild the shoulder.
“The BOMAG ran very smoothly,” added APAC Missouri. “It was a new mill that hadn’t been broken in yet, so there were some minor adjustments that needed attention. But Van Keppel provided us with great support and service. They’d take care of everything in the evening so we were always ready to run first thing in the morning.”
After the Highway 65 job, the BM1200/30-2 moved on to its next task, full-depth removal of shoulders on U.S. Highway 60 in Republic, MO. Just as had been accomplished on the previous project, APAC Missouri tackled the job without a hitch, removing 1,500 tons of asphalt in two shifts.