Drivers on the Illinois Tollway this summer may have seen what look like yellow disk-shaped robots roaming steep, grassy embankments on the sides of the highway, not far from workers wearing safety vests and just standing around.
Neither is exactly what it might appear to be.
The four-wheel-drive machines, which from a distance look a little like giant versions of a robotic vacuum cleaner that sweeps floors and carpets in homes (and drives pets crazy), are actually remote-controlled slope mowers.
The mower is driven and steered using a control panel that can be hung around the neck of an operator standing on flat ground as far as a football field away.
Called the Spider ILDO2, the slope mower is manufactured by Dvorak Ltd. of the Czech Republic. Tollway crews responsible for mowing the grass and chopping down thick invasive brush along the rights of way have nicknamed the $42,000 machine Spider-Man, because to them it's a superhero.
The Spider won't climb walls, but it ventures up slopes and down into ditches at a pitch of up to 40 degrees, where tractors are at risk of tipping over, where riding or walk-behind mowers may not be able to ascend from deep gullies, and where weed wackers simply can't cut it, according to toll authority maintenance officials.
"I like it a lot because it goes where tractors can't go and keeps us safely on top of steep slopes so you don't have to worry about slipping down,'' Paul Borkowski, a tollway equipment operator, said Friday while directing the Spider up and down a hill and around trees in the infield adjacent to the ramp from northbound I-294 to westbound I-90 near O'Hare International Airport.
The slope mower has four blades and four wheels that pivot 360 degrees and it runs at two speeds, "turtle'' and "jack rabbit.''
The Spider cuts a 50-inch-wide swath on each swipe.
"It pretty much mulches the daylights out of the grass,'' Borkowski said.
The tollway owns four Spiders, which were purchased in late 2012 and are getting their first full season of use now, said Michael Zadel, roadway maintenance manager at the toll authority.
"When drivers see it, they are curious and often stop and ask,'' Zadel said.
The machines have performed well and so far have been low-maintenance, said Kerry Brown, a tollway roadway maintenance section manager.
While the Spider has been cost-effective compared with traditional landscaping, the big advantage has been reducing the risk of accidents and injuries, Brown said.
The Spiders have proven to be an especially valuable tool for getting into hard-to-reach spots to trim the brush that grows up against noise walls that separate toll roads from residential neighborhoods, and retaining walls and other areas difficult to access with traditional grass-cutting equipment, Zadel said.
"After we constructed the noise walls we were starting to get complaints from neighbors about the appearance of high grasses because these areas had been mowed before, typically to the fence line," Zadel said.
Now, homeowners are "ecstatic" about the cleaned-up appearance, Brown said. "We satisfied all of our complaints,'' which were received from municipalities including Rosemont, Schiller Park, Northbrook, Glenview and Des Plaines, he said.
"A lot of our good equipment is born of frustration,'' Zadel said.
The tollway usually assigns two equipment operators to each Spider. Besides the control operator, a second worker scouts the area before the Spider goes in to look for large rocks, fallen tree limbs and anything else in the deep grass that could damage the Spider's blades.
In especially steep terrain, the accomplice hooks a cable winch on the Spider to a highway guardrail or a tollway truck, to help pull the mower back up to the top after making the plunge.
"The Spider is a lifesaver in these tight areas,'' said Nick Petrecca, a tollway equipment operator working with Borkowski on Friday.
The Illinois Department of Transportation does not use any remote-controlled mowers, officials said, but IDOT may do so in the future.
"Steep slopes are always risky, and if there are ever any safety concerns, the work is delayed until the ground is dry,'' said IDOT spokeswoman Jae Miller.
Your Getting Around reporter took the Spider for a spin trimming grass around a stand of trees and, despite my low aptitude for playing video games, I pretty quickly got the hang of working the two main toggles — one to turn the wheels and the other to go forward or backward — as well as buttons to engage and disengage the blades, raise and lower the cutting length and control the engine speed.
Borkowski joked that, after growing accustomed to using the Spider, he finds it hard to mow the grass outside his home the old-fashioned way.
"I wish I had one of these. I showed a video of Spider-Man to my daughter and she thinks it's awesome,'' he said.
Dvorak sells a residential version, called the Spider Mini, for about $8,000.
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