HARRISBURG, Pa. (WHTM) — The diamond-shaped orange caution signs as you approach them still show a silhouette of a human worker holding a flag, and maybe they always will.

But increasingly, the flaggers themselves are mechanical. Harrisburg is among numerous cities around the country where “AFADs,” or automated flagger assistance devices — once a rare curiosity — are becoming common.

How well are they working?

Like a lot of things in life, the answer seems to be, “It’s complicated,” not least because “they” aren’t one kind of device. Different traffic control companies use different kinds of machines and — one key differentiator — different numbers of people to operate the machines.

During a drive through a robot-arm-controlled construction zone along Third Street in midtown Harrisburg, a car was driving against the correct flow of traffic; it wasn’t clear whether the car had ignored or not seen the stop sign and electric arm at the other end or had entered the lane somewhere beyond there (for example, from an alley or street parking space). The wrong-way driver, like the other cars, was going slowly enough that everyone stopped in time; the wrong-way driver turned, and the other cars passed.

Would a human flagger have prevented the close call? There’s no way to know for sure, but the near-collision happened within sight of the device, where a flagger would have been standing.

On a different afternoon at the same construction zone, drivers began honking when the arm at their end remained down, and the traffic light attached to it red, for several minutes even though no cars were passing in the other direction. A woman with her window rolled down, who declined to provide her name, said the devices were causing “chaos” and that she preferred human flaggers.

Harrisburg is among numerous cities where AFADs are becoming increasingly prevalent. Matt Maisel, the city’s spokesperson, said the city hasn’t received any feedback — positive or negative — about the devices from residents or people visiting the city.

“It’s just something that is part of a changing world,” Maisel said. He said contractors need the city’s permission to use devices, but the city hasn’t seen the need to say no so far.

“We choose reputable companies for a reason,” Maisel said. “If they are saying, ‘Hey, we want to use this automated flagger system,’ then we trust their best judgment.”

“But everything has to be cleared by the city, first and foremost,” Maisel said.

The two devices surrounding the Third Street construction zone appeared to be operated jointly by one person.

Not so for most AFADs operated by Flagger Force, which has 2,000 employees in work zones up and down the east coast but remains headquartered where it launched 22 years ago in Hummelstown, Dauphin County.

AFADs are “designed to assist a flagger,” said Mike Doner, the company’s founder and CEO. “It’s not designed necessarily to replace a flagger.”

Doner said the company doesn’t rule out adopting other technologies someday, but for now, the two AFADs at either end of a work zone — when the company does use AFADs — are generally operated by two different workers standing at a greater distance from cars than human flaggers typically stand. Flagger Force’s AFADs, which a company employee demonstrated at a facility in Lower Swatara Township, Dauphin County, are also larger than the ones seen along city streets in Harrisburg and elsewhere.

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“We use it in places where it is not safe to put a human,” Doner said. “So for instance, a guardrail where there’s a steep decline, where there’s no ‘escape route.'”

Last week, a worker in a North Carolina construction zone was struck and killed while removing work-zone signage. Doner said that reconciles with his company’s findings that the most dangerous moments in a work zone are during the setup and teardown of work zones rather than while work is happening, when all warning signs are visible and motorists are most vigilant.

Why not take advantage of the potential labor-cost savings Doner acknowledged other companies might be enjoying from using just one human to operate two devices?

“With technology, when something goes bad and you have a single person operating two devices, you’ve got a problem,” Doner said. “So we try very hard to have an employee at or near the AFAD at all times to ensure the motorists understand the signals they’re given, that the device is working correctly and that we can keep everybody safe.”

“In an ideal environment, you have a single employee controlling a single AFAD with a remote control unit, and that allows the employee to be in a safe location while the device is very close to traffic,” Doner said, adding the devices became popular long ago in countries like Australia and Canada — no surprise, he said, given their lower population densities than the U.S.

“Cities are full of people with mobility challenges,” Doner said. “[Current] AFADs don’t address pedestrian control and the safety features for keeping pedestrians safe.”

Still, “recently companies have designed smaller-featured ones or added cameras and radar and things like that. New technology comes along, and we always look at that.”

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