Space Age Grading
Laser and GPS Systems Control Jobsite Productivity
By Jason Morgan

Thinking machines, super computers — gone are the days of pouring over blueprints, as new technology has taken the guess work out of grading. Global position system (GPS), laser and sonic systems sound more like the devastation devices of a James Bond villain, not the latest equipment for everyday contractors. But these high-tech gadgets are popping up on more and more jobsites, allowing contractors to dig more accurate grades than ever.

Ranging from the basic sonic to the more complex GPS, these systems, attached to a mini excavator, skid steer with a plow blade or tractor loader backhoe, sense the ground and alert you if you’ve dug too deep or cut the wrong angle, depending on the job requirements you punched into the machine before hopping in the cab.

“Sonic and lasers use a physical reference point, like the sound wave bouncing off the ground, whereas 3-D GPS systems don’t need a physical model because it gets position information from the satellite,” explains Murray Lodge, director of sales-construction for Topcon. “Because of the need for physical references, sonic and laser systems are mainly used for finish work, after the bulk of earth moving. GPS on the other hand can be utilized from the beginning to the end of the project which is one reason why they have become so popular.”

Although the sonic and laser systems are great for final grading, you generally won’t see just one grading system on the jobsite. Many GPS systems, made by the likes of Topcon, Caterpillar and Trimble, are designed to work in tandem with laser and sonic systems — providing a complete jobsite grading and excavation solution.

Before charging up your lasers and sonic beams and positioning your global satellites to inflict maximum jobsite productivity, it’s important to have a firm understanding of how these complicated systems work. That doesn’t mean plotting star chart coordinates or calculating advanced laser physics; with a general knowledge of the systems, you’ll be able to put your machines to work like an automated army of indestructible excavators and levelers.

Tomorrow’s Grading Future Today

While lasers that disintegrate objects or cut into an impenetrable vault aren’t quite ready for mainstream consumers, lasers that guide the ever-careful blade of a dozing skid steer or bucket of a digging excavator are. And these systems have been around a lot longer than you think.

“Lasers in construction have been around for more than 40 years — making their first appearance on construction jobsites in the late 1960s. These lasers were used as a virtual string line to lay sewer pipe,” explains Norm Skinner, technology solutions representative for Caterpillar. “They were expensive, about $10,000, big, bulky and fragile, with lots of parts that required the use of a truck battery to operate and needed constant readjustment and monitoring. And, these early laser systems would barely fit into the bed of the contractor’s pickup.”

The systems continued to improve with the introduction of automatic leveling lasers a decade later, in the 1970s, which were popular with contractors grading large plots and farmers plowing fields. While laser systems continued to develop into the more sophisticated pieces of equipment we use today — able to dial in a grade and have it projected by the laser in a 360-degree dome light stream that the machine sensors can pick up — sonic grading systems were on the horizon.

“Around 1981, AGTEK released the Sonic Tracker for road work that used sonic sensors to sense the ground and allowed machines to work in both vertical and horizontal grades,” says Lodge. “With the sonic systems, it’s basically a stopwatch that’s connected to a sensor that sends a sound wave to the ground and times how long it takes to get back to the bottom of the tracker. Since I know that rate multiplied by time equals distance, and I know the speed of sound [roughly 344 miles per second, on a good day], I can figure out where my cutting blade needs to be for cutting a curb. I can calculate that my blade needs to be 8 in. deep, dial it into the grader and keep the tracker on-grade.”

The most recent and rapidly growing technology today is a GPS system. Starting mostly in the land surveying industry and migrating over to construction, GPS was first used for machine control and guidance around 1999. Since then, the systems have become more accurate — taking two-dimensional plans, converting them to three-dimensional schematics for accurate digging and offering automated hydraulic controls, with all the info displayed on a fancy graphics display that seemingly does everything except clothe and feed you.

Binary Grading

It’s easy to feel like your construction world is being overrun by robotic machines with all this sophisticated technology. When learning any new technology, it’s best to start slow and understand the basics. Laser systems offer a middle ground between functionality and affordability. A laser system comes in handy when you’re dozing with a skid steer. Basically, there are two modes of operation for laser systems — flat, leveling work or slope work.

“Laser systems typically have a flat or sloped laser,” explains Lodge. “Let’s say I was going to cut a floor. I could set my laser up and tell the sensors on the dozer blade that the floor needs to stay 6 ft below the laser light beam that is transmitted 360 degrees in the air. It keeps the blade on-grade.”

When putting a laser system to work with a mini ex, it allows you to excavate to a site plan without the use of grade stakes. On a Caterpillar AccuGrade system, for example, the laser receiver attachments allow the system to reference a rotating laser to transfer benchmarks over large worksites.

After dialing in your specific grading or excavation requirements, the sensors mounted onto the dozer blade or excavator boom will let the system know exactly where the blade or bucket is. Then the system is able to alert the operator of the grade through a series of colored lights or a graphical display, depending on the system. With this somewhat basic functionality, the laser systems are perfect for building pads, digging trenches and general utility applications.

Let’s face it, a laser system is really just a gateway system — a component that introduces you into the world of grading systems and leads to more complex and productive systems. Today, GPS is where it’s at in the grading system industry.

“With GPS, the contractor can upload the design file from the engineer into a display located in the cab of the machine and the operator can go anywhere on the job and see on the display where he is at, where he needs to cut and fill and all the other information he needs to be highly productive without waiting for the surveyor to show up and set some wood,” says Skinner. “The world of virtual grading is now a reality. On many of the dirt moving machines, the blade is automatically controlled by a simple flick of a switch. Excavator control systems are a lot more complex and are not automatically controlled... it’s only a matter of time.”

Before the machines become self-aware, you have to program them for productivity. When it comes to GPS systems, more than half the work is in the preparation, explains Jason Killpack, Topcon’s senior product marketing manager. The first and most important step is to convert the two-dimensional file (the blueprints) into a 3-D digital terrain model. Topcon systems come with software that takes the 2-D model from IOCAD and translates it into 3-D for the model.

After you have the digital model, you have to localize the jobsite. This means that you are taking the jobsite and tying its physical position with that of the satellites. This is done by walking around the jobsite and placing the hand held GPS rover for a short amount of time on control points put in by the surveyor. The number of points depends upon the size and layout of the jobsite, but you need to provide at least four.

You then take the file from the rover unit and put it into the GPS control box on the compact excavator or skid steer. Now, the GPS system knows where the excavator is on the jobsite and its activity in the programmed job.

Once you get into GPS systems, you’re usually pretty serious about grading, so odds are your system has a graphical display that lets you see exactly what you’re digging or dozing and how close you are to grade. On Cat’s AccuGrade GPS system, light bars visually guide the operator to the desired dig depth; it shows him where to position the bucket for consistent, accurate depths.

Self-Aware Contractors

Even the word “system” implies an inner-connection between components, and that’s exactly what today’s grading systems are — a symphony of lasers, sonic waves and satellites working as one. While a sonic or laser system is a useful stand alone system, the true productivity comes from unifying your machines. From Caterpillar’s AccuGrade product offering, which encompasses site recognition, laser and GPS systems, to Topcon’s grading system offering of sonic, laser and GPS systems, each piece is built to work with the other pieces of the grading puzzle. So if you just want to try out a laser system and then add on GPS, that’s fine and vice versa, as long as you continue to add products from the same manufacturer.

For many contractors, it comes down to price when getting into grading systems. A basic flat laser, sonic or site recognition system can range from $5,000 to $15,000 depending on the options such as the display system. GPS, on the other hand, is a large investment running $30,000 to $55,000, not including the $20,000 base station. The trade off is that once the major investment is made, you can add components such as a laser or sonic system at a fraction of the starting cost. And there’s the added value you get out of maximizing your productivity and bid preparation.

“Many contractors take the rover unit out to the jobsite before they begin to move dirt to verify the volumes they bid compare to what’s actually physically out there,” says Lodge. “If you already started moving material and find that there’s an extra 20,000 yds of cubic material, usually you’re out of luck and you move it at your cost. By having this information beforehand, you can sit down with the developer or owner to ensure you get paid for the material you move.”

Killpack and Lodge mentioned that they’ve seen a 35 to 60 percent increase in productivity when crews implement a grading system. Although some may call it crazy to equip versatile equipment with lasers and GPS tracking systems, the productivity and value gained from getting the job done right the first time overshadows any predictions of a post-apocalyptic future run by crazed robots.

Jason Morgan is assistant editor of Compact Equipment.