So your company wants to increase productivity by eliminating surveyors’ stakes and by making its equipment operators more efficient in their grading tasks. Of course, company owners want to do this while saving money that was normally spent on staking. What company wouldn’t want this? Management gets excited and forks over $80,000+ for a machine control system. Not only is this new equipment expensive, but there are other obstacles that may stand in the way of successful implementation. Site preparation contractors can experience substantial benefits from the implementation of newer construction technologies such as GPS- and laser-guided machine control, but they must carefully consider and adapt their work processes to realize their potential benefits. Eventually, the contractor will understand that the investment extends far beyond the upfront cost of the equipment, adding new considerations of organizational change, labor and procedural modifications.

Organizational and Process Change

For most contractors, there will be significant hurdles to overcome with any technology implementation. They must not only learn new technology from a front-to-back functionality standpoint, but they must evaluate and refine existing business processes as well. To capitalize on the opportunities that technological advancements provide, “traditional” employees’ roles and responsibilities must be redefined; equipment training alone will not be enough. Contractors across the country are realizing these changes with the addition of machine control.

Technology Learning Curve

Machine control technology is far from “plug and play,” and from a standpoint of operation on the jobsite, can be high-maintenance, especially when a downed base station has shut down all of the GPS-enabled machines--and the job itself. To learn, understand and be effective in applying this new technology, the contractor must be prepared to dedicate one or more individuals to its overall operation and maintenance as well as devote training time for equipment operators. Even with upfront benefits realized, it will take a certain period of time to realize the full return on investment due to the “hidden” costs of operation and maintenance. This is especially true when adding other factors such as increased liability, scheduling and the creation/revision of data files needed to build the job.

Engineering Responsibility and Liability

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The traditional delivery of a sitework project versus delivery using machine-controlled data is vastly different. Take a look at the two flowcharts on pages 7 and 9. Among these differences are the steps for a contractor’s submittal of a stakeout request, the engineer’s review of the latest design information to be incorporated into a stakeout job, the actual preparation of the stakeout by the surveyor, and the actual staking of the job by a survey crew.

On the surface, the most obvious responsibility shift for the contractor using machine control is that he now performs work that was previously performed by the engineering or surveying firm: the staking out of the project. With added responsibility comes added liability for tasks such as keeping tabs on design revision and the resulting maintenance of information that is sent into the field for construction. This is a significant role change for the contractor; not only is he responsible for constructing the project according to the design, he is also now required to proactively monitor (and be responsible for) the information as it flows into the field. The contractor must also be constantly on the lookout for design shortcomings and changes, and know how to respond to them to prevent or limit liability.

Field Adjustments

The design looks good on paper and on the computer, but does it work in the field? Unfortunately, there are occasions when design issues do not appear until a surveying crew sets foot on the site and begins to perform stakeout. A sharp stakeout surveyor will spot design issues and either make minor adjustments himself or call the engineer to quickly resolve issues of greater magnitude. Field issues are frequently resolved in this manner--behind the scenes with no heartburn to the contractor.

Removing the surveyor and engineer from the stakeout portion of the process through the implementation of machine control also removes any field QA/QC check these individuals might have performed. For the contractor, this means he will be required to know the project to a greater level of detail than in the past. He will need to obtain an added level of familiarity with project plans so that spotting issues becomes intuitive. Once a question or potential issue is identified, he will need to communicate with the engineer to obtain an effective solution. Some engineers may not take too kindly to the contractor’s added scrutiny of the design (especially if they know that their survey dollars are getting cut), but the engineer who is acting in the best interest of the project owner will be grateful for the added set of eyes that spot potential issues. To stay on top of the project, the contractor’s goal should be to know the engineering specifics better than the engineer himself.

Scheduling

A CASE QUADTRAC 450C tractor equipped with GPS and three Miskin scraper bowls use a data model prepared for the excavation and grading of a football stadium bowl and athletic fields at Adrian College in Michigan.

Sitework contractors working for aggressive developers know the true meaning of pressure and the “time is money” mindset. Developers are notorious for attempting to squeeze the most work into the shortest time period (without worrying about being realistic). In the grade-staking world, engineering/surveying firms frequently request a minimum of 48-72 hours between the time a contractor submits a request to the time the stakeout is performed onsite (this does not include the “I NEED STAKES RIGHT NOW!” expedited requests). The 48-72 hour window allows for the firm to schedule a field crew and provides time for the stakeout to be prepared in the office.

Contractors using machine control must be more aware of their schedules and allocate enough lead time for the adequate preparation of this field information. Obtaining grade information is now more involved than faxing a stakeout request 48 hours in advance. Scheduling now becomes more complex because the lead time includes data prep and management. This will be a huge challenge for the contractor who is adjusting his work schedule on a daily basis to account for fluctuating site conditions, late design changes and other project issues. Poorly managing and scheduling the preparation and use of GPS and laser equipment (including machine-controlled equipment, positioning rovers, etc.) will quickly wipe out any productivity gains and survey cost benefits--and may leave the heavy iron sitting idle.

Documentation

Engineers and surveyors know the critical impact of documentation and traceability for all aspects of a construction project. Surveyors enter data into field books and maintain data collectors as they complete each stakeout, archiving it for possible reference at a later date. If requested or required, additional information may be provided to the contractor in the form of cut sheets that document locations and elevations of stakes and hubs that were placed in the field as well as relative cut/fill amounts. Field books and cut sheets are but two tools used by engineering/surveying firms to create a “paper trail” for the job. This information is crucial in the event that there is a problem with the construction and helps protect the engineer/surveyor from liability.

When the task of staking is removed from the engineer/surveyor, the contractor becomes responsible for providing his own paper trail to protect himself from potential liability. When a project built with grade stakes is disputed, a contractor can claim that he simply built the job according to the stakes, placing the burden of proof more on the engineer/surveyor. But when using machine control, contractors are almost wholly responsible for the portions of the job that are built without stakes. Even if an engineer’s flaw is incorporated into the data model that the contractor assembles, the contractor will have to prove with certainty that he was not the source of the problem.

I Have GPS on my CAT D6, Now What?

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The purchase of a new machine control system is but one piece of the puzzle. With all of the advertising and promotion that goes along with the sale of GPS, laser systems and machine control, probably the most critical component of getting any system to work is brushed over, if not overlooked, by the unsuspecting and uninformed contractor. This component is the digital terrain model (also known as the DTM, data model, surface model, TIN). As the contractor removes survey stakes from the construction process through the use of machine control, he is now faced with the responsibility of creating a data model to be used with the company’s guidance system. To complicate matters, a typical grading plan created by an engineer/architect that receives approval for construction by the local government authorities is almost never ready for field use as a data model. (See the sidebar, “All Grading Plans are NOT Created Equal” on this page.) These plans are not detailed enough to be used directly for construction, especially work done with machine control. The contractor must “convert” the engineer’s grading plan to precisely reflect the way the project is going to be built (including things like hold downs, topsoil strip, road subgrade, etc.).

To create a construction DTM, the contractor (or a third party) will have to be familiar with a surface-generating CAD application to create the data model from the engineer’s design. Moreover, the model builder must have the engineering insight to interpret the designer’s intent with the grading plan. For the contractor accustomed to a roll of construction plans, wood stakes and survey cut sheets, obtaining the DTM capability is a difficult and revolutionary change with potentially heavy liability implications. Because the contractor “converted” the engineer’s grading plan, he is now responsible for providing an added layer of quality assurance and quality control for the engineer’s design. Since the creation of a data model requires great attention to detail, the act of converting a grading plan may uncover design flaws, deficiencies or gaps that weren’t apparent in the 2D construction plans. In these instances, the contractor must use extreme caution in correcting these “flaws”; making incorrect adjustments could translate to a kiss of death in the field in the form of an incorrectly built project.

Data model creation is role-changing for contractors, whether they do it in-house or outsource it to a third party data model provider. It is a difficult hurdle and will require a great deal of unprecedented communication and cooperation between engineers and contractors. Not only are contractors responsible for understanding the GPS or laser equipment they purchased, they now must master (and be liable for) the creation of the information to build a project according to the plans.

The Bottom Line

The potential benefit for the contractor who uses GPS- and laser-guided machine control technology is high, but the rewards will not be obtained without long-term investment and commitment to change. Increased liability, changes to organizational roles and responsibilities, new learning curves, implementation of in-house engineering capability, and sometimes management of engineer-contractor conflicts are only some of the obstacles that await the implementing contractor. For many, overcoming these great (and often hidden) obstacles will be too great to justify the investment in terms of money, labor and the pain of organizational change. However, with the devoted commitment of substantial resources to the execution of a well thought-out plan, long-term benefit and reward will be within the dedicated contractor’s grasp.

Sidebar: All Grading Plans ARE NOT Created Equal

In and of itself, a contoured grading plan in a construction plan set lacks the exacting detail that is required for a contractor to build directly from. In order to obtain approvals, the engineer will create a grading plan that illustrates finish grade contours that are either generated by a finish grade surface or through manual digitization (entered by hand into a CAD application). Typically, the grading plan that the engineer submits for government approval provides a snapshot of the site when all buildings are in place and all grading is finished. The sitework contractor that completes his work prior to any building construction must also determine how to “mass grade” the site to account for things like basement spoil, foundation excavation, sewer spoil, etc. In other words, the finish grade that is shown in the approved construction plans likely will not reflect what is constructed by the contractor prior to building construction.

While some engineering firms may provide the contractor with a “hold-down” amount (an amount to lower the finish grade of a building to account for spoil generated by the excavation of basements/foundations upon building construction), it is rare for the engineering firm to provide an intermediate “mass grading” plan solely for construction purposes. Further complicating matters, site features such as road vertical curves, road intersections, pavement edge of metal, drainage swales, top of curb, and detention pond banks (top and bottom) are often only sparingly detailed. The grading plan as shown in a construction plan set may be acceptable for the approving planning commission and township board but not for construction using DTMs and machine control. The contractor must take it upon himself to arrange for the checking of the grading plan and supplementing it with the necessary detail to create a DTM that can be used for construction.