E-ZPass IAG-TDM specs now open source, available for download, "aids national IOP" - Kapsch, IAG

April 25, 2013
By Peter Samuel

2013-04-25: Kapsch has released the specifications of the time division multiplexing (TDM) protocols used in E-ZPass electronic toll collection signaling. Both patented and unpatented proprietary codes associated with what has been called the IAG system are now an open standard, free for all to download and use, says Chris Murray, president and CEO of Kapsch Trafficom North America, based in McLean Virginia.

Kapsch bought the rights to the IAG-TDM protocols in 2010 when it bought Mark IV Industries, the Mississauga Ontario startup company that had written the initial RF signaling codes about twenty years ago and defeated the toll industry leader TransCore (then Amtech) in the competition for the world's biggest electronic toll procurement conducted by the Inter Agency Group (IAG) of E-ZPass.  Mark IV made many additions and tweaks to the codes over the years since they have to work in an array of tolling environments from the dense traffic of New York City through the highspeed of the Ohio Turnpike to small bridges across the Delaware and Hudson Rivers.

The IAG-TDM protocol is now available to "all interested parties" including competing toll system suppliers free of any royalty and in perpetuity. The only requirement, Murray told us in an interview yesterday (the news was provided under an embargo against use until 8am Apr 25) is that those downloading the protocol sign a license agreement in which they commit to make available without restriction any derivative or supplementary applications or code they write for the IAG-TDM.

He called this a "circular license" in that those accepting Kapsch's offer of a free and in-perpetuity right to use Kapsch's IAG-TDM must agree to allow everyone else similar open access to any variants or supplementary routines they develop on top of IAG-TDM.

Keeping 'open' code open

Chris Murray said this is designed to prevent what has happened to some ostensibly open standard protocols with add-on features and slight variants to an open standard being declared proprietary. He is referring to competitor TransCore's development of the eGo and SeGo protocols. While substantially based on the open ISO 18000 6B standard they have features, mostly related to encryption on which patents and other proprietary rights are claimed.

That effectively gives TransCore a monopoly in supplying equipment and tags in Texas, Florida, Oklahoma and the Carolinas where their eGo and SeGo protocols are used in toll operators readers and in motorists tags. It is a potential obstacle to national interoperability in that TransCore could legally challenge use of 3M or Kapsch readers to read SeGo tags.

Toll operators in Georgia, Utah, Colorado and Washington state as well as at the Canadian border (Ambassador Bridge) and British Columbia have moved to adopt next generation 6C sticker tags and readers as an open standard only to find 6C vendors 3M and Neology in court over alleged patent infringement.

Murray says the 'circular license' requires others to pledge to keep open for everyone all supplements and derivative routines of IAG-TDM protocols they might create. Without it there is nothing to stop the IAG-TDM  being fragmented and going the way of 6B.

He said Kapsch for its part will make all upgrades and amendments to IAG-TDM open.

In a prepared statement Murray is quoted:

"Open technology benefits everyone and accelerates the adoption of standard solutions. We will continue to actively support open, non-proprietary protocols and technologies and are committed to make these available to the market which is to the benefit of everyone in the industry ? from toll agencies to the road user."

TransCore's security argument

TransCore has made no public statement of its policy on use of eGo and SeGo but toll operators quote TransCore as offering privately to negotiate licensing arrangements for competitors to use eGo and SeGo. TransCore argues that security will be better preserved if it retains ultimate responsibility for the encryption algorithms that are the company's major addition to the 6B standard.

We asked Chris Murray of Kapsch about that argument. His response was that open or licensed makes no difference. Security is only as good as the operators make it.

Murray says that the IAG-TDM system has what he calls a dynamic security algorithm that provides each tag with a unique identifier. It is up to each organization managing IAG-TDM electronic toll collection to maintain security over their accounts. He says in almost twenty years of operation there has not been a single case he has heard of in which the E-ZPass security system has been successfully penetrated. He says nothing will change with the IAG-TDM an open system. Its security will remain as good as its management by the toll agencies using the protocol.

Reverse engineered

What of their competitors already reverse engineering IAG-TDM? He says that it's better for everyone if they don't feel the need to do that because it's fully open.

Reverse engineering may get the protocols 99.9 percent right but the one in a thousand error rate will cause problems.

And the posting of all the code should remove any remaining legal doubt, he says, about Kapsch's commitment to open standards.

Kapsch is promoting the use of the 5.9GHz WAVE protocols a high capacity wireless data transfer technology being adopted in the longdistance trucking business. 5.9GHz is also the system around which many ambitious vehicle-to-vehicle and vehicle-roadside safety schemes are being trialed - with possible mandated installation in all new cars.

IAG applauds

In the statement on the Kapsch move PJ Wilkins executive director the E-ZPass Group is quoted:

"We applaud the efforts of the Kapsch team in supporting the 25 member agencies of the E-ZPass Group with our efforts to advance nationwide interoperability of electronic toll collection systems. The E-ZPass Group has and will continue to support industry efforts toward nationwide interoperability. The release of the TDM protocol for both tags and readers is a significant step towards that goal."

IAG-TDM specifications should be available to be downloaded from 8am eastern April 25 at the Kapsch TrafficCom website:



Also available on the E-ZPass Group's Interoperability page:


TERMINOLOGY: The E-ZPass IAG and others in the industry have commonly referred to these specifications as "IAG protocols." And most maps showing the different electronic toll protocols around the country call them IAG. Kapsch and the E-ZPass Group (which has dropped the name IAG) is now calling them TDM for time division multiplexing. (Actually there are other protocols that use TDM, for example ASTMv6.) We're using the composite term IAG-TDM for ease of understanding - editor.

NOTE: I tried for a license but couldn't complete the form. It wanted a 'Title'? Since I hate 'mister' I applied for a real title 'Lord' first. That was rejected, then 'Sir' got rejected too, so I gave up. I remain untitled. Do I need to research Austrian titles? Ah, maybe the politicians self-mocking title 'Honorable' will do it...? (And we always thought naively before coming here that the American revolution had tossed the awful British titles on the trashheap of history where they deserve to be. Sadly no.)

LATER NOTE: Kapsch is changing the form so that filling in a Title is no longer mandatory. All egalitarian anti-titlers can celebrate!


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