GPS Speeds Earhart Road Project
A 3,500-foot section of Earhart Road north of Plymouth Road in Ann Arbor Township has been widened. The project also included re-ditching and the installation of new storm sewer and culverts. The existing roadway was milled and resurfaced. The approximately $600,000 project was completed in July. C & D Hughes, of Charlotte, was the prime contractor for the project.
Steve Strasser, project manager with C & D Hughes, said that traffic was a challenge on the project. "The road is posted as closed, but there are many businesses on that corridor, so traffic and safety are obstacles," Strasser said.
C & D Hughes used a Trimble global positioning system (GPS) on a Cat AccuGrade-ready D6K dozer. "The GPS system is working great. It shows your subgrade elevation and gives you the top of your sand subbase. We are installing 10 inches of sand subbase and there will be 6 or 8 inches of aggregate base on top of that. Asphalt will be placed on top of the aggregate base for the widened areas," Strasser said.
"You see everything on the screen and you get a quality product. You know what your quantities are. Midwestern Consulting, of Ann Arbor, is the consulting engineering firm on the project, which is also doing the layout of the project. So, we'll have our GPS records of quantities as far as earth moved and sand installed which can be compared with their records." Strasser said that the GPS system provides accuracy and much greater efficiency.
C & D Hughes used the Cat D6K with the Trimble GCS900 single mast GPS system with a cross slope sensor to do fine grading on the project. They also had a Cat AccuGrade-ready D6N dozer with a Trimble dual mast system on the project. Components of the system include a Trimble MS990 antenna, a Trimble CB430 display and a Trimble SPS851 base station. The survey rover includes the SPS881 receiver and TSC2 controller with the SCS900 construction software.
"They had a very tight schedule. This project had such a short timeframe that they felt that there was no way they could finish it on schedule using conventional methods," Jason Winger, of Site Precision, said. Site Precision, of Grand Rapids, is a Trimble dealer. Winger said that C & D Hughes decided to use both dozers with the GPS units on the project. The GPS units saved the contractor a considerable amount of time.
"It's not the easiest grading job, either. There are three big curves on this road, and they are super-elevated curves. You're coming out of one super-elevated curve and you have a very, very short distance before you're coming into another super-elevated curve. At the same time, you've got very steep ditches on either side of the road. It is a staking nightmare. They would've had hundreds of stakes out there. They would've had to stop a lot, pull strings, check grade, and shoot it with a laser. The dozer flies right through there with the digital model loaded into the machine," Winger said.
"When they fine grade — let's say their sand layer and gravel layer — their engineering inspector is going along with them and they are booking grade with C & D Hughes' rover. The SCS900 software records every shot you take in a text file format that you can open in Microsoft Word or Microsoft Excel. It records all of the information of that shot: time and day and cut and fill information for verification later. So, they're booking the grade with the engineering inspector on the site and then they hand that text document to the engineer so that the engineer has as-built information and they have all of those booked grades for the project. So they have all of the documentation from the contractor at the end of each day. The system also speeds up pay estimates."
Subcontractors on the project include Barrett Paving Materials, Inc., of Superior Township (asphalt paving); P. K. Contracting, of Troy (striping); State Barricade, of Warren (traffic control); and GM & Sons, of Whitmore Lake (concrete curbs).