Company Overcomes Concrete Dowel Drill Spacing Challenge with E-Z Drill

Accuracy, efficiency and speed. For roadwork, where meeting deadlines to minimize road closures and disruptions to motorists are key criteria for landing projects, they’re crucial. And as Chester Bross Construction recently demonstrated on Nebraska Highway 92, it’s worth the effort to get horizontal concrete drilling and doweling machines that are exactly suited to the job.

Nebraska 92 stretches from the state’s western border with Wyoming to Omaha where the highway leaves Nebraska and enters Iowa, taking motorists through farmland and several towns and counties across the state. It’s also a major roadway that branches off of Interstate 80 and leads motorists through Polk County, Neb., where a recently completed road project is enhancing safety for motorists. The entire project included diamond grinding the surface of the road, replacing areas of the road that had suffered excessive wear, and paving the highway’s earth shoulders which required over 40,000 doweling holes that had to be spaced twice as far apart than normal.

In May of 2013, the Nebraska Department of Roads (NDOR) initiated the resurfacing, restoration and refurbishing project. In addition to making the roadway safer, the project was intended to reduce maintenance costs associated with maintaining the highway’s earth shoulder. The NDOR awarded the concrete work to Chester Bross Construction, which was ready with its fleet of E-Z Drill pneumatic concrete drills.

The Spacing Constraint    

Headquartered in Palmyra, Mo., Chester Bross Construction is part of the Chester Bross group of companies that includes C.B. Asphalt and C.B. Equipment. Over the past 40 years, Chester Bross Construction has specialized in paving and general construction projects including work on highways, parking lots and driveways.

Like many two-lane highways in agricultural areas, Nebraska 92 in Polk County is traveled by more than just cars, minivans, SUVs and the occasional semi. It’s also a road that sees a lot of tractor traffic, and its earth shoulder was showing the effects. Most tractors didn’t fit within the road’s 11-foot-wide lanes, so farmers drove along the shoulder, which was made up of compacted dirt and aggregate. The tractors caused considerable damage and created an uneven surface, which was a serious safety hazard for motorists. In addition, the surface of the road itself was excessively worn and had started to show major irregularities.

The Polk County project replaced 21.6 miles of the earth shoulder with concrete and increased the width of each lane to 12 feet to provide adequate stable area for tractors and increase safety for everyone on the road. Chester Bross Construction replaced 5,427 square yards of pavement that had settled excessively, as well.

The crew had to perform the grading, culvert, paving and guardrail work within 160 days. And all that new concrete meant a lot of tie bars and a lot of dowel drilling. The Chester Bross crew of 16 had to drill a total of 40,492 holes, 9 inches deep to tie 18-inch rebar into the existing concrete. Also, because the shoulder is far less traveled than the main roadway, it required less reinforcement from tie bars, so holes could be spaced every 33 inches, 21 inches wider than typical roadway projects. While this reduced costs and the number of holes by 65,000, it created a challenge for Chester Bross Construction – the company’s drills could only achieve a maximum of 30-inch concrete core drill spacing.

“This is a fast pace for this type of work, which created a challenge to get the project done in the timeframe with the equipment we had,” said Tim Bennett, operations manager for Chester Bross Construction. In addition, the crew could only work on two miles of road at a time. While this is normal for most two-lane road projects, it added to the challenge. It didn’t allow the crew to drill all the holes for the project before pouring concrete, which would have been most efficient. The crew had to take each two-mile section from start to finish, before moving on to the next. The company had to make sure its E-Z Drill equipment was up for the task.

E-Z Drill manufactures a variety of concrete dowel drills, including on-grade, on-slab and equipment mounted units that offer up to five gangs. At the time, Chester Bross Construction already had several E-Z Drill models, including two 2-gangs and several single drills. The company considered modifying its two 2-gang drills for 33-inch spacing, but it wouldn’t give them optimal efficiency. It would take over double the time to reposition one concrete core drill as opposed to the possibility of repositioning just one drill that could accomplish several holes at once.

For this project, Chester Bross needed a fast and efficient drill that would allow it to drill more holes at a time without pulling some all-nighters to get it done before the deadline. Bennett decided it was time for a new drill. He contacted equipment dealer Cummings, McGowan and West to see what it had to offer.

Building a Resolution

Cummings, in St. Louis, Mo., carries concrete and asphalt equipment. Chester Bross had already purchased several of its E-Z Drills from the store, so Bennett worked with Cummings salesman Dan Doherty on a solution.

“After briefly talking with Tim about his situation, I knew his best option would be at least a 4-gang that is modified to meet the concrete core drill spacing requirements,” Doherty said. He contacted Randy Stevens, vice president of sales at E-Z Drill to see what could be done.

“We come across many of these situations that challenge our customers’ efficiency,” Stevens said. “Having the extra gangs and the right configurations can be the difference between finishing a project and finishing it on time.” Stevens added that when jobs get delayed, contractors could face penalties. To keep Bennett and his team on track, he recommended the E-Z Drill 210-4SRA 4-gang Slab Rider that could be modified to achieve a maximum of 33-inch spacing. In addition to drilling four holes at once, the drill auto-aligns and quickly repositions itself after each set, which helped the team work quickly and efficiently. And like all E-Z Drills, it was adjustable so that once the project was completed, Chester Bross could use it for more typical projects that require less spacing. The drill also can be configured to drill vertically for high curbs and barrier walls.

The Payoff of Preparation 

Work on Nebraska 92 began on June 1, 2013, with Chester Bross opening up the first two-mile stretch on the west end near the Platte River. “Once we prepared the subgrade on two miles, it was critical we got the drilling done as fast as possible,” said Bennett. “The new drill doubled our productivity from what we would have experienced with our 2-gang models, and that allowed us to stay on track and meet the deadline.” With the new 4-gang drill Chester Bross was able to drill more than two times faster than what they would have achieved with the 2-gang drills.

Bennett also noted the crew didn’t have to spend time repairing areas of road that suffered inadvertent damage or perform maintenance on the drill. “We worked six days a week, so to have a drill with no downtime really optimized our time,” he said. “And since the drill gathers its point of reference from the top of the concrete slab, it didn’t disturb the subgrade and provided accurate measurements between holes.”   

As the drilling and shoulder work progressed east, Chester Bross also replaced 11 areas of severely settled concrete. The company used its 210B SRA single-gang model E-Z Drill to drill 242 holes into the existing concrete slab for the tie bars. Bennett said the single-gang worked great for these areas.

Having the right drills gave Bennett and his crew the accuracy, efficiency and speed they needed to wrap up the project in late October 2013, right on time.  “Hitting the deadline is important for every project, but it was especially important for this one,” he said. “That’s why we have used E-Z Drills for the past 15 years.”