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Those curious rods hanging from a Dulles Toll Road power line serve a purpose

The Washington Post logo The Washington Post 10/31/2020 John Kelly

Heading out the Dulles Toll Road I see what look like microphones hanging down on vertical lines over the Metro tracks. What the heck are they?

Dave Sproul, Bethesda, Md.

They do look a bit like microphones — specifically, the long, skinny condenser microphones that are frequently positioned above drum sets in recording studios. But that’s not what they are. Nor do these rods sniff out radiation, speeders, toll scofflaws or any of the other threats we might conceivably face on Washington-area highways.

No, these are more like the tennis balls some people hang from string in their garages to help them safely park their vehicles. Pull in too far, and you’ll destroy the workbench and recycling bin.

You’ll see two of the contraptions over the Silver Line tracks where Hunter Mill Road goes under the Dulles Toll Road/Route 267. They are designed to remind people working below that there are power lines above.

“Basically, it’s a safety precaution used mainly during construction periods to ensure people are staying a safe distance away,” Dominion Energy’s Rayhan Daudani wrote in an email to Answer Man.

[Bright idea: Yellow grids make utility poles more visible at night]

The rods originally had brightly colored flags hanging from them, a warning to workers laying Silver Line tracks that making contact with the lines above them could be deadly.

As Marcia McAllister of the Dulles Corridor Metrorail Project wrote in an email: “These were placed so any high equipment — cranes or excavators and dump trucks — would be made aware of the location of the wires and the operators would know to stay away from these overhead wires. These may be left there in case WMATA maintenance ever needs to bring tall equipment into the area for any follow-up maintenance work during their years of operation.”

Rayhan explained that the power line has an insulator hanging from it, which has a fiberglass rod inside. Around the rod are silicon polymer discs known as sheds. At the bottom of the fiberglass rod is a stanchion, and that’s what the flag would be attached to.

The stanchion is made out of noncorrosive materials — usually galvanized steel, aluminum or a bronze alloy. Wrote Rayhan: “In this case, it looks like the lines are likely transmission lines and the flag may have worn off over time. We don’t want to shut down lanes on the toll road or put someone up in the energized circuit if we don’t need to, which is why the flag portion hasn’t been replaced.

“We generally leave them up as it’s still important to keep a minimum approach distance once the line is energized. Contact is not only dangerous, but can also knock out a circuit and leave 5,000-10,000 people without power.”

Several power lines traverse the toll road, but these appear to be the only ones strung with these particular safety devices.

There’s a rather more low-tech approach on Route 7 west of the toll road. Route 7 is being widened from there to Reston Avenue. The numerous utility lines that cross the road are strung with orange fabric panels, which flutter in the breeze like so many Tibetan prayer flags.

Mow better blues

Jane Brown, a reader from Burke, Va., wrote back in September that she was curious about how often the Virginia Department of Transportation mows the grass in the median strips.

“I was told once by the supervisor’s office that the grass is only cut three times a year,” she wrote. This seemed inadequate, given that grass along Braddock Road and Burke Lake Road had gotten so high that it required a small team of men with weed eaters to cut it down.

Ellen Kamilakis of the Virginia Department of Transportation said there are three mowing cycles a year in the district that comprises Arlington, Fairfax, Loudoun and Prince William counties. The three cycles are generally mid-May, mid-August and early to mid-September. (There’s an extra cycle in Fairfax, funded by the county.)

“We adjust those cycles as needed in dry or wet springs and summers,” Ellen said.

Some areas are not cut at all because they are “no-mow zones” planted with plants that attract pollinators.

Ellen said VDOT encourages residents to get in touch if they notice a safety issue, or sight distance issue, with roadside vegetation. You can visit my.vdot.virginia.gov or call 800-FOR-ROAD and, she said, “we can remedy it quickly.”

Questions, please

Curious about something you’ve spotted in our area? Send your question to answerman@washpost.com.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.

a car parked in a parking lot: Rods made of metal and fiberglass hang from a power line over the Silver Line tracks that run alongside the Dulles Toll Road. Flags once hung from the bottom, a reminder to construction workers below to be careful. (John Kelly/The Washington Post) Rods made of metal and fiberglass hang from a power line over the Silver Line tracks that run alongside the Dulles Toll Road. Flags once hung from the bottom, a reminder to construction workers below to be careful. (John Kelly/The Washington Post) a clear blue sky: To at least one Post reader, the things look like microphones. (John Kelly/The Washington Post) To at least one Post reader, the things look like microphones. (John Kelly/The Washington Post) a car parked on the side of a road: Construction below has finished, but Dominion Energy sees no reason to remove them. (John Kelly/The Washington Post) Construction below has finished, but Dominion Energy sees no reason to remove them. (John Kelly/The Washington Post)
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