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March 5, 2009 / Jim Fenton

An Irish RFID Tale

Image from decade_null via Flickr

Image from decade_null via Flickr

Last summer, an Irish cabbie illustrated for me one of the unintended consequences of the use of RFID.

My family and I had just arrived in Dublin, and we were taking a taxi from the airport to the Citywest Hotel, where the 72nd IETF meeting was being held.  This involved driving on the M50, a toll road.  In the midst of heavy traffic, as we approached a toll barrier, the cabbie (while driving) reached over, opened the glove compartment, and removed a shielded antistatic bag containing a transponder.  He attached the transponder to his windshield went through the toll barrier with the transponder allowing him to be billed for the charge.

I asked the driver why he didn’t just keep the transponder on the window.  He explained that the transponders are used for more than just paying for tolls in Dublin.  They’re also used to pay for parking charges at garages.  Someone he knew had the misfortune of driving past a garage exit just as a car was coming out, and the passer-by’s transponder was read by mistake and charged for the exiting car’s parking.  So this cabbie keeps his transponder “turned off” by putting it in a shielded bag in his glove box whenever he’s not actually using it.  Pretty inconvenient.

Why not just put an on/off switch on each transponder?  There is the question of cost, of course, but the bigger issue is that the transponders are bought by the toll collection authorities.  If it was easy to turn the thing off, undoubtedly some fraction of people would forget, and the enforcement burden would rise (or the collection rate would fall) as a result.

The real problem here is mission creep.  The transponders are being used in applications for which they weren’t designed.  There aren’t many passers-by near a toll booth like there are near a garage exit.  Perhaps there should be a button on the transponder to permit it to be used for any of these secondary applications.  But of course the transponder has no way to distinguish its primary mission (road tolls) from secondary applications such as garage fees.

RFID has lots of interesting applications, and lots of problems too.  The security and privacy concerns with RFID are well documented, but this is an issue I hadn’t considered.  It was interesting to see how much a cabbie in Dublin knows about it.


Leave a Comment
  1. Barry Leiba / Mar 5 2009 10:24 pm

    I used to keep my EZ-Pass transponder in its bag, as the Dublin cabbie does, but not for that reason: I didn’t like seeing it when I looked up at my mirror. And I don’t use it that often, so it wasn’t a big deal to take it out and put it back. Then there was a while when I used it a lot, and I got used to leaving it on the window — finally adjusting its position so it’s completely hidden by the mirror for me.

    We can use EZ-Pass to pay for parking at the airports, but not at arbitrary parking garages. And, of course, there are few passers-by at the airport parking exits, at least given the short range involved. I find the garage scenario odd, though, and I wonder if the cabbie’s story doesn’t amount to an urban legend. The setup at the parking garage should be that the exiting car stops at a barrier, and that the barrier lifts when the system reads the transponder. It shouldn’t have to read it from a moving vehicle, so the reader should be directional and aimed inside the garage. It should also be set up to register only the strongest signal it gets during its read cycle. It shouldn’t present a field strong enough, outside the garage, to read and prefer the passing transponder.

    Of course, the reader could just be badly (cheaply) implemented.

    • Jim Fenton / Mar 5 2009 11:01 pm

      I’ll have to agree that the cabbie’s story does have a certain amount of urban legend flavor to it. But suppose that the driver leaving the garage doesn’t have a transponder (so no issue about finding the strongest signal) and sits at the barrier for a little while fishing around for change. That gives more opportunity for a passing vehicle with a transponder to satisfy the parking bill.

      It’s true that the reader should be directional, but if the reader is also being adapted to this task from something else, they probably just used whatever antenna was available.

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