Wednesday, May 2. 2007

RFID Sensors Underground

I've noted in the past my delight with Underground Focus magazine. It covers underground locating topics and each issue has too many pictures of fires, floods and explosions typically caused by heavy equipment hitting underground pipes and wires. I got to see some of the locators up close. They are from 3M (yes, they make everything!) and is designed to work with 3Ms electronic markers. The markers are cool – one version of the markers is a 4" diameter ball inside of which is a bladder of an "anti-freeze" like substance inside of which sits basically a passive RFID chip (no internal power, so they last a long time). The ball and internal materials are biodegradeable and safe for the environment. The balls come in different colors (and use different frequencies) to mark water, sewer, comm and other underground infrastructure. Why the anti-freeze? These are going underground and you don't want them to freeze. Moreover, swimming in the liquid the chip will float horizontally, providing the best signal. Basically, the chip is "self-leveling."

Now, the markers can be "dumb" that is not contain any info (those are cheaper) but for a few dollars more you can code them (and recode them) with data of your choosing: when the pipe was laid, the contractor, etc. One clever piece of data relates to materials far below the surface. The balls work to about five feet (other markers can be found to 8 feet), but there's no reason you can't drop a ball that contains information that says that the pipe/wire/etc. is another 10 or 20 feet below it.

The end user basically plays "treasure hunt" by setting the locator for the type of target marker is of interest (water, sewer, etc.) which sets the locator to send out the right frequency for that market type. Then as you get close you see and hear you are getting close. You can even use the locator to report the distance from the tip to the marker.

How do you use these? When you dig a hole to fix or lay new infrastructure you drop markers at key points (like turns or when diameter changes, etc.) For long straight-aways you can use the cheaper "dumb" markers to save money. The rep from 3M explained that while the technology has been around a while (four states require use this exact or similar technologies) the company is still spreading the word.

Now, for the GPS part. You can hook up the locator to a GPS to capture locations to be mapped either when they are dropped or when they are later located.

[Disclosure: Bentley covered travel, hotel and food.]

Posted by Adena Schutzberg in RFID, Bentley BE 2007 at 13:57 | Comment (1) | Trackbacks (0) |

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This sounds a lot like the technology used by back-country skiers and alpine rescue workers to find people buried under avalanches. Each back-country skier is supposed to carry a radio-wave beacon that also acts as a receiver and locator for finding buried companions. It might also be similar to the new RECCO system used at major ski resorts to locate avalanche buried skiers who have RECCO tags (presumably RFID) on their ski clothes.

#1 Andrew on 2007-05-03 06:50 (Reply)

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