E-ZPass (and other active RFID) transponder lifespan reports

[davewiecking]

But aside from that, my understanding is that even an active RFID transponder like E-ZPass doesn't allow for two-way communication. Someone correct me if I'm wrong, but the transponder basically spends its lifetime just broadcasting its identity nonstop: "Here I am–number 006946732" . So with the existing equipment, anyway, there wouldn't be a channel for the toll plaza to signal the transponder with information like "balance low"  or "call customer service" .

EZpass - actually company named Kapsch, which owns technology - has quite complex communication protocol. It is, generally speaking, accessible to public - but some paperwork has to be signed before getting access as Kapsch still owns the thing.
They specify 500 kbit/s for both uplink/downlink; quite respectable bandwidth for the purpose I would say..

When seeking further details, ask The Wik ('cause that's where The Goog will lead you anyway):

The E‑ZPass transponder works by listening for a signal broadcast by the reader stationed at the toll booth. This 915 MHz signal is sent at 500 kbit/s using the TDM (formerly IAG) protocol in 256‑bit packets. Transponders use active Type II read/write technology. In April 2013, Kapsch (purchasers of Mark IV Industries) made the protocol available to all interested parties royalty-free in perpetuity and is granting the right to sublicense the protocol.

Footnote leads to this Kapsch press release.

[1995hoo]

Regarding lights or beeping, I believe the older hard-case SunPass transponders beeped when you paid a toll, but those have been phased out.

[Beltway]

My Virginia EZPass, not sure how old, probably about 10 years.  Used regularly several times a week on Richmond RMA tollroads, and on some trips thru NoVA HOT lanes.

[UCFKnights]

The 2nd Generation I-Pass used in IL (we are on 4th Gen now -- the small Flatpack) beeped and had a LED screen on it with Toll Paid and Balance (and also had a replaceable battery). So there had to be some 2-way communication for that to work. And AFAIK its still the same technology powering I-Pass, and that early 2nd Gen I-Pass I think still works

The 1st Gen I-Pass, the black dash-mounted transponder, I believe was a different vendor and different equipment, and that design had a pretty short life. But if memory serves, it also had an LED display for balance and toll paid. Its been a few years since I've seen the old black I-Pass, so I could be wrong. ISTHA was already getting rid of those by the late 90s, I believe

Also, according to the ISTHA website, the I-Pass/E-ZPass transponder receives a "wake up" signal on approach to a toll plaza, roughly 300' before the Tag Readers. That also tells me there is some type of 2-Way communication, tho I guess that doesn't have to be 2-Way

The old active RFID sunpass's were 2 way communication. In the car, you'd get a green light for successful payment, yellow for low balance, reload soon, and red for unactivated if I remember right. The battery life was fairly short though... 2 years tops. I was amazed that they were able to communicate and figure out your balance that fast as you drove under the gantry, and also amazed that their method of indicating a low battery to you was a letter in the mail.

[hbelkins]

Apparently there is no centralized E-ZPass license plate/vehicle registry. When I had two failed reads of my West Virginia unit in Pennsylvania, they looked up my plate info and sent me the violation notice via mail. I got it waived when I sent proof of my possession of a West Virginia-issued E-ZPass.

[kalvado]

But aside from that, my understanding is that even an active RFID transponder like E-ZPass doesn't allow for two-way communication. Someone correct me if I'm wrong, but the transponder basically spends its lifetime just broadcasting its identity nonstop: "Here I am–number 006946732" . So with the existing equipment, anyway, there wouldn't be a channel for the toll plaza to signal the transponder with information like "balance low"  or "call customer service" .

EZpass - actually company named Kapsch, which owns technology - has quite complex communication protocol. It is, generally speaking, accessible to public - but some paperwork has to be signed before getting access as Kapsch still owns the thing.
They specify 500 kbit/s for both uplink/downlink; quite respectable bandwidth for the purpose I would say..

When seeking further details, ask The Wik ('cause that's where The Goog will lead you anyway):

The E‑ZPass transponder works by listening for a signal broadcast by the reader stationed at the toll booth. This 915 MHz signal is sent at 500 kbit/s using the TDM (formerly IAG) protocol in 256‑bit packets. Transponders use active Type II read/write technology. In April 2013, Kapsch (purchasers of Mark IV Industries) made the protocol available to all interested parties royalty-free in perpetuity and is granting the right to sublicense the protocol.

Footnote leads to this Kapsch press release.

Which is great - but to get actual specs, you need to fill up some forms... and tell the company about yourself - tell them more than I want them to know if my purpose is just more or less random forum discussion..

[theroadwayone]

I was thinking, shouldn't transponders have some sort of color-coded light system to show it's life or your account status?

Are you talking about having status lights on the transponder itself? (There are colored status lights on many toll plazas, but they're being phased out because of federal regs stating that R-Y-G signals should not be used to indicate toll payment status.)

I think a problem with having lights on the transponder is that the lights–even low-power LEDs–would drain enough power that it would significantly shorten the effective life of the transponder.

But aside from that, my understanding is that even an active RFID transponder like E-ZPass doesn't allow for two-way communication. Someone correct me if I'm wrong, but the transponder basically spends its lifetime just broadcasting its identity nonstop: "Here I am–number 006946732" . So with the existing equipment, anyway, there wouldn't be a channel for the toll plaza to signal the transponder with information like "balance low"  or "call customer service" .

That said, my California FasTrak has a tiny piezo beeper that chirps once when it has been read by a toll plaza (or other equipment–I've had it beep unexpectedly entering airports and similar facilities, even where there isn't a "park by FasTrak"  kind of option). I don't know if that's an example of two-way communication or whether the transponder is merely sensing the presence of whatever radio signals that the sensing equipment emits.

I got a FasTrak account earlier this year to use the I-15 fast lanes; a while ago they updated their system so transponders don't beep in the lanes, but they should on the state's toll roads and bridges (and parking.)

[J N Winkler]

Along the same lines, I believe I posed the question in another thread some time ago: Is there any penalty to not using your transponder? At least in the PTC's setup, the answer appears to be "˜no'. The same seems to be true of California's FasTrak and Florida's SunPass.

The Illinois Tollway discourages I-Pass holders from relying on video backup tolling, though it does so by creating FUD instead of laying out hard enforcement thresholds.  Their website just says that you may face higher fees or sanctions of some kind if you have a transponder and accumulate too many video tolls:  how many is "too many" is never specified.

But I think I also asked: Since cameras already have to be installed at all toll lanes to catch violators, and since toll road authorities have also made the investment in the computers and software necessary to automatically read license plates, why is it necessary to have transponders (and the associated sensing equipment) at all? Just do toll-by-plate for everything but require that motorists register an account and set up a funding source first.

In addition to the counterarguments you have already outlined (in unquoted parts of the post quoted from above):

*  If you have a transponder, tolls are posted to your account effectively instantaneously (especially if the transponder is local to the system and attribution of toll does not require lookup of other agencies' customer files), which is useful for documenting travel for expense reports, timesheets, etc.

*  Frequently video tolls are applied not to the car that actually incurred the toll, but rather a different vehicle registered in another state that has the same license plate number.  I cannot prevent myself from receiving bills in error for tolls incurred by cars in other states that have the same license plate number I do, but I can at least reduce the likelihood that registered keepers of those vehicles will receive bills for my travel.  (If you think errors of this kind are a remote contingency, remember that a large share of toll agencies do not handle video tolls in-house where staff can be held to high QA/QC standards, but put this service out to bid and choose the lowest bidder.)

[jeffandnicole]

My Virginia EZPass, not sure how old, probably about 10 years.  Used regularly several times a week on Richmond RMA tollroads, and on some trips thru NoVA HOT lanes.

The original equipment had batteries of a very short life span.  The newer batteries last way longer.  NJ sent us new EZ Passes at around the 10 year mark to replace our current passes, which they do to specifically keep your EZ Pass from eventually going dead on you.  2 of the EZ Passes I had gotten as extra and never used.