Site Prep

Getting Real With Machine Control

by Joseph V.R. Paiva PLS, PE, PhD

October 1, 2004

• ARTICLE TOOLS
• Share
• Reprints
• Print
• Email

(Or how do I get started, and who can help me?)

The use of sophisticated, modern measuring tools such as Real-Time Kinematic (RTK) Global Positioning System (GPS) and robotic total stations has radically changed the operational and financial picture of construction surveying. In recent years the technology behind these tools has been transferred to construction machines--including bulldozers, graders, excavators and scrapers--and has provided great efficiencies for the firms using them. When GPS and robotic technologies are coupled with other sensors that tell the machine’s control display unit where the cutting edge is with respect to the existing and design surfaces, the operator is able to work more efficiently to convert the designer’s work into reality. With this advanced technology now installed on heavy equipment, it is even possible for these machine control systems to perform the grade adjustments within the final few tenths of a foot automatically by controlling the machine’s blade or bucket directly.

But, getting to this “real world of machine control” requires dedicated effort. Interested firm managers must ask vendors tough questions and do rigorous financial and operational analyses before deciding on and implementing such systems. What are some of these steps? Let’s take a look at some of the implementation challenges facing acquirers of these new technologies, and consider how to successfully tackle these issues.

The Four Aspects of Machine Control

Tom Seiler, GPS marketing manager for Seiler Instrument and Manufacturing Co. of St. Louis, says that there are four main aspects a contractor should investigate when considering to implement machine control: the survey aspect, the machine aspect, the data prep aspect, and the installation and training aspect. “When we go over these [aspects] with the contractors, they readily understand what the issues are, even if they don’t know exactly how to tackle them,” Seiler says. As with many new technologies, the buyer, who is the contractor, often doesn’t know what challenges he will face. Time after time, contractors who have successfully installed and operated machine control systems for their earthmovers will say that having a dealer who understands the challenges, and more importantly has, in partnership with the contractor, the means to deal with them successfully, is the key to a machine control success story.

The Survey Side

For machine control to operate successfully, the surveying infrastructure needs to be rock-solid. Without the usual frequency of visual guides such as stakes, laths, ribbons and markers, a machine operating on the undifferentiated landscape can wreak havoc if a strong network of surveying control doesn’t exist. Reliable surveying control is necessary at the site to ensure that the “digital staking” is properly set and immovable. Having surveyors, whether in-house or subcontracted, who understand the needs of machine control is important. Machine control just does not tolerate piecemeal coordinate systems or, as is sometimes the case, no coordinate system at all. The consultant’s responsibilities include understanding the datum and the coordinate system to be used project-wide. This involves sound management and a project control focus on the part of the surveyor, who must consult with the designers and project managers to ensure that all are indeed “on the same page.”

The control must also be properly set and coordinated, and both the surveyor and contractor must know that machine control is being used on the site versus conventional tools. On sites where machine control is applied, there is a need to place the control systems out of harm’s way. But equally important is setting control that is accessible to dozers and graders. Without such machine-accessible control, it is not possible to check the calibration and accuracy of the machines, which in effect have become giant surveying machines, or at least extensions of a huge, integrated surveying system.

For those instances where control on the site exists from different sources, the surveyor’s job includes coordinating them all into one system and publishing the coordinate values in all three axes. This should be done regardless of whether the machine control is done in 2D or 3D, or with RTK GPS or robotic total stations (or both). If one coordinate system is established, then there will be no ambiguity or uncertainty about the values to be used for machine check stations, instrument and backsight setup points, or bench marks and reference points used to check the quality assurance of the surveying systems.

The Machine Side

Of course, the contractor supplies the machines: the bulldozers, graders, excavators and scrapers. To make these machines “machine-control capable,” the contractor must rely on the dealer and the manufacturer that the dealer represents to make sure the complete--and appropriate--kits are ordered for the tasks at hand. Contractors should be aware that much variation occurs from year to year in the details of a machine such as a bulldozer, and even from model to model. Thus, it isn’t enough for a contractor to tell a vendor “I’ve got a D-6” when ordering components for the machine. Using in-house experts who know the intricacies of these machines is one of the many ways machine control dealers must “equip” themselves to be sure they properly provide service to their clients. Masts, cables, hydraulic valves, radio modems, displays and computers, antennas and prisms, GPS receivers… this is where the majority of the money is spent to equip the construction machine.

It is also now possible to equip some of the machines with automatic controls, so that instead of providing a guide on where the cutting or biting edge must be, the system itself controls it. When equipped with automatic controls, the machine still requires an operator, partly for safety reasons, but even more importantly because on early passes, the machine doesn’t “know” that positioning the blade for all of the four feet of cut is not the way to get the earth moved. Once most of the material has been moved out of the way, the automatic system works wonderfully and consistently to grade the last few tenths of a foot.

Contractors must plan for machine downtime from one to two days, depending on whether they are equipping their machines for 2D or 3D work, and depending on the complexity and size of the machine itself. When automatic control is required, the job takes longer--often two to three days--since the hydraulic system must be modified. Generally, this time includes installation of all the system components as well as testing of the newly configured machine. Dealers typically send out crews to do the installation at the contractor’s machine yard, or as is frequently done, at the contractor’s jobsite. Often, additional labor is required just to situate parts into place, and the machine operator or mechanics provide technical input to make sure the installation is properly done. In some cases, the dealer contracts with third parties to do the installation.

  When it is the contractor’s first experience with setting up total stations or GPS base stations, the dealer will often spend additional time with the contractor to instruct the contractor’s crews on how to perform these vital setup tasks, or to provide background information to the contractor’s project managers to ensure they can monitor the work done by surveying consultants and be able evaluate their effectiveness. “Generally, we find that contractors understand the problems of installing hardware on the machine that is welded or bolted to it, or where we have to tinker with the hydraulics,” says Greg Fearon, vice president and general sales manager of FLT Geosystems, a surveying instrument dealer in Ft. Lauderdale, Florida. “The hardest part is working with their personnel on the math and surveying aspects--and that is where if they don’t have those skills internally, a surveying consultant can be a good partner for machine control implementation.”

The Data Preparation Side

The aspect of data preparation is the quietest and least visible of the phases of making machine control come to life. Because data preparation is often overlooked, it can be the most troublesome for the contractor. Understanding the issues and making sure that qualified data prep experts are handling this, whether at the contractor’s office, the designer’s office, the consulting surveyor’s office or in the dealer’s office, will make the difference between a smooth transition to machine control and a long--and often prolonged--expensive mess. “Learning about the data prep process is a little bit of a surprise [for most contractors],” says Randy Stewart, branch manager and 3D machine control sales manager of Pacific Survey Supply in Wilsonville, Oregon. Here again, the contractor is dependent on the dealer to provide guidance on how to manage the data prep side of the machine control equation. The ideal situation occurs when the designer knows that machine control will be used on the site and understands exactly how plans and data are to be prepared to create the digital data to be used by the construction machines. However, the key to successful machine control, according to Stewart, is proper data preparation by machine control-qualified consultants.

At least during the first few projects (and as-needed thereafter) when implementing machine control, a qualified and reliable team is essential--one that can analyze the design plans (whether on paper or digital) and assess the work needed to be done to transfer the designs to the machines. It is a good idea for this same team to then perform the data prep work. Sometimes, especially if the job is small, the dealer can provide this support. A few dealers even provide this service as an ongoing business. Most dealers know of consultants who truly understand the intricacies of data preparation for machine control. They can recommend a list of such consultants to the contractor, and at that point it is up to the contractor to hire the appropriate one. In many cases, these consultants may have worked hand-in-glove with the dealer on early projects of another contractor, or the consultant may have sent a team to be trained by the manufacturer (most can provide documentation, short courses or consultants to help their surveyors learn this new aspect of managing and quality controlling geodata). Dealers often recommend self-taught consultants who have achieved good results from working with other contractors to provide data prep services.

A contractor must know that even when plans have been digitally prepared, they may not be machine control-ready. To make the plans complete and ready, the designer of the data must have specifically understood that digital files customized for the contractor’s machines were also to be prepared. If the designer does not know this, then seldom will the paper and digital documents be complete without the assistance of a geodata prep team to bring that data into machine control readiness.

For machine control to be fully effective, the digital files on each construction machine must have data that is specifically geared to that machine. This includes a digital terrain model (DTM) file representing the finish surface (for that machine) to provide guidance to the operator on the cut or fill required, based on the position and elevation of the current position of the blade. It generally also shows enough surface details (such as existing fences, roads, designed lot lines or pavement or shoulder edges) on the operator’s display for the operator to “get the picture” of what he or she is attempting to build.

The Installation and Training Side

Most of the installation and training issues of machine control have been covered in the previous sections. However, two key points remain to be discussed. One important part of the installation step of machine control involves the creation of a digital file of the machine’s measurements that are installed in the machine’s registry. This is the machine-specific calibration that relates the horizontal and vertical offsets of the prism or GPS antenna (or points when it is a dual GPS antenna system) to the edge of the blade.

Another important aspect to machine control is operator training. This is usually done immediately after installation, if the machine is onsite or if there is a test site near the machine yard. Typically, this can take anywhere from a couple of hours to a couple of days depending on the situation. When the machines (operator-trainees) are relatively close to each other onsite, the dealer’s trainer can train several at the same time. Many times, the initial reaction of operators to the implementation of machine control has been resistance. But after a short time working with the new system, quite often only a day, the resistance diminishes or disappears entirely. One of the most important parts of operator training is teaching them to check in regularly at the control installed by the surveyor and to evaluate whether the machine is still in calibration. This calibration check is often done by locating a corner of the blade over a stake and measuring its distance above the stake, calculating that elevation and comparing it with the value on the machine’s display. “When we do training, we often work with a machine control ‘champion’ within the contractor’s organization,” Pacific Survey Supply’s Stewart claims. “The champion is involved in observing all aspects of the training of others and the installation of the system. They observe the data prep process. This gives them the ability to be the in-house support for the machine control system.”

The Inside Details on Geodata Preparation

Very often a consultant will use a CAD expert who is intimately familiar with surveying, as well as a surveyor to get the data from design drawings converted and prepped for loading into a machine. The consultant’s work will also include any work necessary to get the system up and running, including verifying control, making sure the published coordinate values are in the right system, adding control and check points for the construction machines and the people doing quality control, setting up the base station if GPS is being used, and collecting any supplementary surveying data that may be required to make the data onboard the machine as complete as possible. Other work that may be required of the consultant includes being on-call to handle problems and performing quality assurance. Services such as staking for curb and gutter or utilities like sewers may also be provided by the consultant on certain jobs--the concept of “stakeless grading” hasn’t done away completely with red and blue tops.

“It doesn’t matter whether the plans are produced on paper or digitally,” says Mark Mosby, CAD manager at Cole & Associates Inc. in St. Louis, a customer of Seiler Instrument. “For us to successfully transfer the information to the dozer or grader, we have to examine every piece of the design, especially when it is assumed that the contractor can build it by going from template to template. Depending on the complexity of the project, we sometimes have to construct our own cross-sections and generate profiles at key points using the existing and design surfaces at 5-meter intervals on straight portions and as small as 1-meter intervals on curves to make sure there are no problems.”

The consultant’s CAD expert needs to transfer the horizontal alignment, vertical profile and typical cross sections into the machine so there will be no gaps or “holes” when the system determines its position and tries to determine grade at that location. Every template must transition smoothly to the next, and there can be no ambiguity. Discontinuities can make the system inaccurate, unreliable or incorrect. Thus, the CAD expert may have to tweak the details provided by the designer to make sure that continuity exists between cross sections, especially if the work being done is a complex site grading operation or a complex road project. Particular care needs to be given to checking the data for smoothness around ditches, transitions, superelevation and widening.

The Benefits of Early Implementation

“When it’s all done properly, it is very gratifying to hear the stories from the contractors,” says Cole’s Survey Manager Terry Westerman. “[Recently], Seiler installed a system on a grader, taking one morning to do it. The DTM prepared by Cole was put on the machine. By the end of that same day, this newly equipped grader had been used to lay down and grade the base rock for 1,600 feet of a two-lane road. By the end of the following day the asphalt paving was complete.”

Fred Weber Inc. of Maryland Heights, Mo., was contracted for a project recently for the Missouri Department of Transportation (DOT). This project was the first time Fred Weber had used machine control. Instead of holding up progress while the machine control was being prepped, Fred Weber asked Cole & Associates to get started the conventional way, later transitioning to machine control. “The idea was that the contractor could start the earthmoving, and once machine control was ready to go they would have a graded surface to compare with, and a way to compare productivity as well [between conventional staked grading and stakeless grading]. The conventional/digital approach really worked for them,” Westerman says. Where the two surfaces prepared by conventional and digital methods came together, the difference was indistinguishable. “The contractor was impressed that when we had their operators drive up to a check stake, the vertical difference missed by less than the width of a little finger.”

The crowning touch in the Missouri DOT project was when the contractor was able to use the DTM prepared for the graders and bulldozers in the GPS equipment used to do quality assurance. Handheld GPS rovers and vehicle-mounted units were used for this purpose. The quality checking proved near perfection. With a well-prepared digital model, the machines were able to get the grading done with no mistakes. The common problems of mistaking the notation on a stake and cutting where fill was required just did not happen. A key element of successful integration of machine control, says Westerman, is that “the radical difference in technology means that you have to have an open mind about the process you invent--you have to let the technology lead you.” Even as a consultant to the contractor, this new form of surveying services has required a radical change at Cole & Associates--in the number of personnel in a crew (reduced), the number of crews (increased) and the technical skill and knowledge of the crew (much increased).

With this system, it has been no problem to handle changed conditions onsite, according to Cole’s Mosby. “A telephone conduit was found during excavation that nobody knew about before the work started,” Mosby explains. “We sent out a crew, surveyed it, sent the information to the designers, evaluated and prepped the data from the new design, and a new card was ready for the earthmovers in under a week.”

Bruce Flora, owner of Flora Surveying Associates in Glens, Va., has been working on machine control projects along the eastern seaboard for four years. His advice to contractors: “Don’t assume electronic files from designers are correct until you or someone you trust has checked them. You never know what you will get. Making sure you can get the cooperation of the engineers is important, but sometimes it can be difficult. But above all, work on building a relationship with a long-standing, qualified dealer with good support capabilities. Don’t go for the cheapest; look at service, inventory and troubleshooting capabilities. Ask questions about what they will do for you if a system goes down.”

“When we sell machine control, we aren’t selling a product so to speak: it is a process,” Stewart says. “So selling involves training the customer in the process. Because changes occur periodically, it is important that the contractor plans for periodic updates and re-training as well.”

Applying All Four Sides of Machine Control

Contractors involved in grading sites and building roads are implementing machine control with great enthusiasm. Because it is a newer construction process, a little investigation of the technology, the manufacturer, the dealer and sources of technical assistance to implement the system will have a huge payoff in both the short and the long term. Some contractors have progressed sufficiently and have a decided competitive edge. As Flora remarks: “The technology is here. Stand on the wayside and watch it go by you. Get onboard before you have to play catch up. Jump onboard but have a plan for what you will do next.”

Joseph V.R. Paiva PLS, PE, PhD
Joe Paiva is a professional surveyor and professional engineer, and has obtained his doctorate in civil engineering. He is a published author, speaker and consultant to developers and marketers of products for the positioning industry.

Comments (0) Post a Comment

Did you enjoy this article? Click here to subscribe to the magazine.

• Home
  • Subscribe
  • eNewsletter
  • Subscription Customer Service

• Online

  • CONEXPO News
  • Videos
  • Industry News
  • New Products & Equipment
  • Construction in the Headlines
  • Web Exclusives
  • Calendar
  • Cartoon Gallery
  • From the Vault
  • Dirt Talk Blog
  • Photo Galleries

• Current Issue

  • Cover Story
  • Features
  • Columns
  • Equipment Focus
  • Attachment Focus

• Resources

  • Archives
  • Digital Edition Archives
  • Career Center
  • Industry Links
  • AEC Store
  • Market Research
  • The Orange Book
• Site Prep Info
  • Contact Us
  • Editorial Submissions
  • eNewsletter
  • List Rental
  • Media Planning Guide