Point of Beginning

Locking in the Benefits

July 29, 2003
DOT surveyors discover a lesser known total station function.



Dennis Danowski holds a rod with a 360 degree prism that gives the Autolock even greater locking power.
Since their introduction in 1990, servo-driven total stations have become one of the fastest selling equipment segments of any type of total station, according to a recent industry study. Servo—or motorized—total stations include options such as direct reflex (or reflectorless), Autolock (or auto-tracking, auto pointing and automatic target recognition) and fully robotic, the most popular of the servos. Less understood than robotic but rapidly gaining devotees, the Autolock total station is emerging as a popular choice for many private sector and Department of Transportation (DOT) surveyors across the nation. Able to track the prism more accurately than the human eye, Autolock instruments can increase accuracy, speed and productivity. Here, Wisconsin and Wyoming DOT surveyors weigh in on their use of servo instruments’ lesser known cousin: Autolock.



Lipsky points the total station in the general direction of the prism; Autolock finds it and locks onto it automatically.
Wisconsin DOT (Wis/DOT) surveyor Tom Lipsky, RLS, knows cold. It’s when the Wisconsin winter windchill factor is 10 below zero and he’s standing in front of his total station, eyes watering, fingers numb. It’s when he has to focus on a prism all day doing cross sections down a frozen highway, checking and rechecking the focus, pushing those buttons through thick gloves.

But now it’s August and those frozen moments are behind him. And now he has Autolock technology.

“Autolock speeds up having to manually sight your target,” says Lipsky, who’s been with Wis/DOT for seven years. “The time you save is great, but it also saves a lot of eye strain. In winter months it speeds up the process even more; all you need is a pen or pencil to enter descriptions on the keyboard.”

Whether it’s summer or winter, an increasing number of surveyors are discovering the benefits of Autolock—or auto-tracking—total stations: increased accuracy and speed, greater productivity and ease of use, decreased fatigue and eye strain. Over the past few years, DOTs have gained substantially from Autolock functionality. Among them are Wisconsin and Wyoming. WisDOT’s arsenal of Autolock total station instruments round out 20 percent of their total stations, and Wyoming DOT (Wy/DOT) currently tallies 30 percent of its Autolock instruments with direct reflex (DR) (their goal is to move to 100 percent Autolock instruments at all sites throughout the state).

“For what little it costs, we’re moving in that direction,” says Curtis Clabaugh, PE, LSIT, Wy/DOT photogrammetry and survey engineer supervisor. “It’s a big plus for not much more money. Everyone wants to go RTK GPS and RTK is great, but there are some places where you still need to use a total station. We use both and that works well for us. They’re ideal complements to each other. In fact, my crews argue over who gets the Autolock units; that’s how hot this technology is.”

Wis/DOT’s Lipsky started with a Geodimeter (now Trimble) servo total station (Trimble, Sunnyvale, Calif.) in 1998. Wis/DOT District 2 Construction Survey Coordinator Gail Vukodinovich told him about the Autolock advantage. So when they upgraded the district’s total stations to Autolock, Lipsky jumped on board.

“Just the idea of not having to manually sight the prism sold me,” Lipsky says. “If you have to take a bunch of shots for topo or cross sections, it makes your time more efficient. If the terrain is open, it can save at least one-third of your time.”

Lipsky recently worked on the reconstruction of State Trunk Highway 164 near Slinger, Wis., northwest of Milwaukee. With crew partner Dennis Danowski, Lipsky needed to perform volume calculations, so they measured using cross sections for the two-mile project, including the roadway and side roads. For the majority of the project, they used Autolock. “We’d set up in a middle spot where we can get about 800 feet each way,” he says. “One setup gives us about 20 stations and the rod guy just walks from station to station getting cross sections along the roadway. Autolock follows him all the way. We took thousands of shots along the two-mile project.”

The instrument person points the gun in the general direction of the rod, and Autolock finds and locks onto the prism automatically. “You can set it up to find it by itself, but it’s even faster if you just point it in the general direction,” Lipsky says. And using a 360 degree prism gives the Autolock even more locking power than with a regular prism, Danowski adds.

“It doesn’t matter whether the target is facing the instrument or not,” Danowski says. “With the 360 it can lock on the prism quickly and easily. If you’re using Autolock I’d recommend it [the prism] to anyone. If you go for it, go for it all.”

Vukodinovich, who logged nine years in the field as a DOT surveyor and 10 as crew coordinator, also helps train Wisconsin state troopers to use total stations for providing critical information in accident reconstruction work. Used to measure crash scenes for legal documentation, total stations have become the “biggest assets in the program since we bought them,” says Thomas Erdmann, Wisconsin state trooper and certified crash reconstruction investigator. “The accuracy of measurements, the time we save in measuring and the information gathered is so useful in our speed calculations.” That’s not surprising to a surveyor, especially considering that prior to total stations they measured by hand with steel tapes. And their introduction to Autolock technology this year has been even more welcomed. “They’ve been doing back flips since they got them,” Vukodinovich says.

Lipsky, with crew partner Danowski, measures final cross sections to perform volume calculations.
Erdmann’s district has three Trimble total stations, all with Autolock technology. “It’s been a lifesaver for night measurements,” he says. Accident reconstruction investigators will often do their work at night, after traffic has died down and there’s less chance of getting hit. While safer, it makes measuring more difficult. “It’s really hard to find the prism at night, especially when going from short to long shots,” he says. “With Autolock, you can whiz through those scenes really quickly; it finds and follows the prism for you.”

Erdmann recently logged 37 hours at a crash site in Waukesha, Wis. A sport utility vehicle had run a red light, lost control and rolled over. Erdmann used Autolock to measure the vehicle for a crush analysis, enabling him to determine speed before, during and after the crash. He also took all road measurements, including skid marks, road signs, traffic marks and the final resting place of the vehicle. In accidents where vehicles are impounded, he’ll set up the total station in the garage using a peanut prism for a vehicle profile. Comparing the crush measurements to an unmarred vehicle of the same make, they’re able to determine how much energy it took to crush the vehicle, thus helping zone in on impact speed.

“We rely on our Autolock total stations now and don’t want to do a crash site without them,” he says.

Kevin Brookshire has worked for Wy/DOT for 14 years and moved from a regular servo instrument to a Trimble 5600 DR 200+ Total Station with Autolock almost two years ago. He noticed a difference immediately. “Autolock is a lot quicker than servo,” he says. “As long as nothing blocks its view of the prism, it stays on the target and moves as fast as a guy can walk. If it loses lock, it’s really easy to get it back: you just get close enough and it locks on. It’s a real time convenience.”

Brookshire recently did a utility survey for a road reconstruction project in Cheyenne, Wyo., that included adding on and off ramps to a portion of the existing highway crossing the railroad. Brookshire located all fiber optic, phone, underground gas and cables, as well as all sanitary sewer lines and storm drains. “It was a full-blown utility survey,” he says, adding that he’s expecting to go back out to do supplementary DTM collection of void areas and additional topographic features before construction starts.

Brookshire also used the Trimble ACU on-board controller for the job and found it made data collection much easier. “You didn’t have to worry about an external data collector or cables,” he says.

“It was beneficial using the Autolock and ACU on this project,” Brookshire says. “The instrument guy would put the ACU in the Tracking and Continuous Topo mode, and as long as I stayed on the same feature code and same line, he’d record the shot as fast as I could walk and get the rod plumb. It cut our time by over half; we got anywhere from 700-800 shots a day when we did that. It’s just so quick.”

“The only time you stop is when you tear down and set up,” he says. “You run out of range and move to the next point. As soon as you set up and go, it’s just going down the road.”

Wy/DOT surveyor Jeff Glissmann upgraded to Autolock in January and quickly grew to appreciate the technology. “I prefer the Autolock—it’s the only way to go for speed,” he says. “We’d run 400-500 points a day using conventional methods and that would be a very good day. With Autolock and the ACU, we’d easily almost double that. It improves our efficiency and is easy to train people on if we have somebody new on the crew.”

Glissmann used his Autolock total station on a year-long $10 million Central Ave. and Yellowstone Road project in Cheyenne, Wyo. One of the major urban intersections in the state, the Central and Yellowstone project included a mile of city streets requiring slope staking, blue topping, pavement lines, staking curb and gutter, storm sewers, utility moves, box culverts and bike paths. “Pretty much everything you’d see on a highway construction project happened here,” he says.

“It was phenomenal, the speed with which we are able to put in stakes in all phases of construction staking,” he says. “I can get more done each day. And it’s easy—because it stays on the rod person, you can move them where you need them in a shorter amount of time, which increases our productivity. The contractors like it because they don’t have to wait for us; they can get in there quicker to build the road.”

Glissmann also uses the ACU with Autolock. “It’s easy to switch between menus and projects,” he says. “It’s so much faster and more efficient than other data collectors I’ve used. The technology has improved so much; it’s a real time savings.”

Whether he’s doing interstate highways, subdivision roads or city streets, Glissmann says Autolock technology allows him to use smaller crews. “I can do the same amount of work with fewer people in less than half the time,” he says. “With Autolock you can catch a stake where it needs to be in a shorter amount of time.

“Not having to manually or physically turn the instrument to your rod person [because] it literally follows you wherever you go—that’s the best thing about it. You can step back and let the instrument do its thing.” You still have to stay alert, he adds; you can’t nap. “But it gives you the chance to watch the entire project picture without burning yourself out looking through the instrument all day. It’s easier on the operator.”

Glissmann started surveying 24 years ago using chain measure and is grateful for technology’s impact on his job. “It’s really the best thing since sliced bread,” he says. “I appreciate this technology; it’s made life easier out here. I know we’re just scratching the surface of what it’s capable of, but give us time and we’ll really excel with it.”