Dirt Talk: Machine Control on West Virginia’s Corridor H
by Harry O. Ward , PE
November 1, 2009
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The Corridor H project is designed to take advantage of the mountainous scenery in West Virginia.
While presenting at a West Virginia survey conference, I ran into a friend, Ted Garrett of J.F. Allen Co. Garrett attended one of my 3D machine control data prep classes a couple of years ago. He mentioned that he was working on one of the longest road construction projects in West Virginia. In fact, it is the second-largest project awarded in the state. This $52-million project is a 5-mile section of the Corridor H Highway at Old Fields.
The overall project is known as Corridor H, a $2-billion, four-lane highway development through the Appalachian Mountains that will eventually extend more than 100 miles across eastern West Virginia from Wardensville to Elkins. The various phases of construction are shown in Figure 1.
This new highway, which is one of the few new highways under construction in America, is not only designed for safety but also to take advantage of the spectacular scenery of this mountainous state. After Garrett told me about his approach on this project, I invited him to step up and speak to the audience about his accomplishments, which he graciously did.
Figure 1. Phases of construction for West Virginia’s Corridor H. Source: www.wvcorridorh.com/route/lrgmap.html.
After attending classes in the art and mathematics of data prep, Garrett performed the 3D prep that several projects needed--but he took his task one step further than most people. His experience as an operator allowed him to sit in the dozer and build the sites that he developed in 3D.
He learned the relationships between the equipment and the data. He learned the need to understand and interpret engineering drawings in order to turn them into something constructible. He learned firsthand how his data could transform a project from merely satisfactory into successful and profitable. And all of his experience came into play on the Corridor H project.
Figure 2. The Corridor H project runs from Wardensville west through Moorefield (D). It meanders through Scherr (A) and continues west to Elkins and beyond. Source: Google Maps.
A typical project like this would have high costs for survey stakeout due to the heavy tree cover and harsh vertical surroundings. A lot of effort would be expended to get survey crews to stake the project out. Line would be cut in dangerous conditions, steep elevations would have to be overcome and stakes would be computed and pounded every 50 feet of the job for the 5-mile length. Stringline would normally be established throughout the job. It would all add up to setting hundreds of grade stakes with associated stringline to guide the construction.
Average costs for performing this type of survey stakeout on a typical job is about $1,200/day for a field crew. That crew can lay about 1,500 LF of string/day. Although it’s impossible to know what the cost would be to accomplish this stakeout under these conditions, we can estimate that it would take at least a month of field crew work and would cost at least $25,000. For a project with this level of difficulty, it is inarguable that those costs would escalate rapidly. (Note: These numbers are based on industry averages and can fluctuate.)
J. F. Allen and Co., however, proved that there was a more cost-efficient method of construction to meet the client’s needs--3D GPS machine control.
An aerial viewpoint of a completed portion of Corridor H. Photo courtesy of J.F. Allen & Co.
Just for the mainline of this 5-mile, J.F. Allen projected that there would have been around 1,000 grade stakes per lane and 2,000 stakes total. Garrett adds, “As every construction surveyor knows, when you drive a stake it will be run over at least once during the job, so additional staking beyond that was anticipated.” J.F. Allen was allowed to set grade stakes every 500 feet on the access roads, which accounted for around 10,000 feet of additional roadwork.
According to Garrett, “J.F. Allen Co. was able to accomplish this task because of the pride we take in our work and our excellent work ethics. We checked the grade randomly to make dead certain that we had the grade to specification. We could not have done without the skills of party chief Rob Hoover, his crew of John Welch, Brian Messenger and Jake Shriver, and grader operator Pip Belt.”
As the material was being placed and graded, the elevations and grades were closely checked against the stakes and they hit dead-on. The machinery, the data prep model and the machine control hydraulics were all working as expected, the job was progressing nicely and the accuracies were excellent.
In summary, the survey staking costs actually ordered for this long roadway project was reduced almost 90%. The 10% that was retained was well worth the peace of mind for checking the construction accuracies.
A pond model built for construction on the Corridor H project. Image courtesy of J.F. Allen & Co.
Harry O. Ward , PE
hward@harken-reidar.com
Harry O. Ward, PE, is a registered professional engineer, a state licensed contractor and certified in machine control. He is president of Harken-Reidar, a new infrastructure solutions company. He has been a member of the engineering faculty at George Mason University since 1997.
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Title: Corridor H - it sux to be a surveyor!
By: Martinsburg Surveyor
Posted: December 2, 2009 11:23 AM
Kudos to JF Allen and Mr. Garrett, they appear to be handling this recession well. Are you hiring? :)