STANDARDS: Framework for e-toll interoperability laid

Major progress toward greater compatibility of different systems was reported Mar 19 at an ITS America Roundtable on Dedicated Short Range Communications (DSRC) held at Reston VA. There should be a North American DSRC provisional standard for future generations of electronic toll and other kinds of vehicle-to-roadside communications equipment agreed upon by later in the year. Two out of three ‘layers’ are ready for balloting and the third seems to be a matter of months away. No strong disagreements remain to be resolved, just a number of slow-to-work through technical issues.

The North American standards work is being driven by congressional pressure to specify a national US standard for equipment funded by the US government and also by the European push for an international standard at the ISO. North America already has de facto regional standards for the present thriving generation of electronic toll equipment, which has been established via toll agency tests, competitive contracts, and a desire of neighbor agencies for interoperability and collaboration. The three separate regional systems (Amtech in the US South, Mark IV in the east & mid-west, TI-now-Sirit in California) are overlaid by the Raytheon-formerly-Hughes/ASTMv6 standard as used by trucks over wide areas of North America and for tolling in Ontario. There are reports emerging of isolated instances of interference due to the incompatibility of the ASTMv6 versus the Amtech and Sirit standards at border crossing applications, and perhaps at toll plazas, but it is not clear these are serious or frequent enough yet to force early adoption of the emerging ASTMv7 standard equipment in the field. The big opportunity for new ASTMv7 toll equipment will come from about 2002 onward when the present transponders, mostly used for tolling, cease functioning because their 7-10 year life batteries have run down.

Rick Schuman of ITS America and the able chairman of the conference said he hoped that by 2005 most vehicles, toll authorities and truck regulatory agencies would be working within ASTMv7. Such compatibility will allow information-based applications (in-vehicle signage and links to onboard computing) to thrive and in conjunction with elelctronic cash spawn multitude of new services.

Jones caught by rocks: USDOT’s Bill Jones told the meeting that congressional mandates being written into law have the department “between a rock and a hard place.” There is some standards enthusiast on a committee staff who keeps slipping in clauses into transp funding bills requiring USDOT to specify national standards now for new equipment in projects receiving federal funding. None of the existing regional/truck standards are acceptable or fully compatible with one another, yet the emerging ASTMv7 which addresses the incompatibilities will remain provisional until it has been field tested in 1999, and perhaps 2000. Jones said they have to wrestle with that within USDOT. (see Logsdon quote.)

All the major vendors were represented at the Roundtable. They all expressed support in principle for the ASTMv7 at the meeting but all said they don’t have ASTMv7 products ready and that their development and production plans will depend on their assessments of the viability of the market for these products (see other quotes). ASTMv7 seems most likely to be installed in trucks first — because (1) trucks need the ability to work with different region’s systems, (2) the standard-hungry feds may use their leverage here, and (3) the existing Raytheon/ex-Hughes/ASTMv6 equipment already sold to truckers is most readily adapted to ASTMv7.

The only problem is that a lot of truckers hate governments, state and federal, and are distrustful of equipment that could help those ‘gaardamned boorocrats’ track ‘em and regulate ‘em. A truckers association rep at the meeting said most truckers will pay “very little” for equipment that interacts with government. They will pay for tags for electronic tolling, in which they see value, but that’s about all.

Objects: Rick Schuman said that the group’s priorities have been (1) Hippocratic Oath — do no harm to existing systems (2) it is all about migration, or how to get in an orderly way to a set of specs which reduce interference and allow interoperability between the four N. Am systems (3) go for one tag which allows multiple applications — embedding the brains and the cost in the roadside equipment (4) accomodate expansion and new uses (5) keep costs low (6) think North American problems first, international second (7) seek a balancing of these objectives.

The agreed ASTM v7 accomodates backscatter and active transponders in synchronous and asynchronous modes and their joint operations. It is in the established 902 to 928MHz bandwidth with no mention or provision for 5.8GHz. ITSA has filed with the FCC regulators for supplementary spectrum at 5.8GHz but there is very little interest in gaining that among DSRC vendors and the filing may well flounder, especially as everyone is determined to hang onto 902-928MHz. In the ASTMv7 discussions there were no moves to accomodate 5.8GHz which is regarded as higher cost, more difficult and unnecessary — something that other countries may decide to do for their own reasons but which has no attraction for North America.

The physical layer 1 document is agreed upon and layer 2, the data link is agreed, except for the question of where fragmentation of messages is handled — within the Layer 2 air interface or in the layer 7 IEEE P1455 specs, the software or applications layer. A lot of this work is hard drafting. The groups are working for maximum commonality with CEN-278, the European standard at the air interface and systems operation level. However members of the American writing groups say bluntly they think the work of their European colleagues is excellent in conceptualization but quite shoddy in implementation.

Brusseltalk: They are working to incorporate as much as they can of the applications layer (L-7) of the European CEN-278 standard into North American standards, both to limit the amount of international differences and to take advantage of the European work. But have been slowed down by what they say is a mess of confused, unnecessarily verbose and obscure writing. The more the experts here get into a detailed examination of CEN-278 the more problems they find. The N.Am group hired a CEN expert who came over from Europe to try and interpret its more obscure sections.

They are going through the European standard — which was unsuccessfully pushed (see TRnl#21 Jan 98 p1) for adoption as-is at the ISO — section by section, rewriting it in clearer English for the specifications of data links and the IEEE P1455 standard describing the applications or layer 7.

Lee Armstrong who is in charge of the North American standards building exercise for an ASTM standard under contract to USDOT said that the European standard writing together with the push for international standards have been a positive influence in accelerating the North American standards work and of getting the CEN-278 document reviewed in great detail by the American writing groups. The threat of having CEN-278 adopted as an ISO standard has spurred the N.Am examination of it and the American effort to complete layers 2 and 7.

But Armstrong said much of CEN-278 is very poorly written.

“Six different engineers sit around read a given section (of CEN-278) and you will get 4 or 5 different plausible interpretations of what it means. We need far clearer language to have something we could take to a professional standards organization here.”

The N.American writing group has had discussions with their European counterparts, who agree the CEN-278 document is obscure on many issues. Unable to clarify what it means, or uninterested in literal adherence to the standard, they told Armstrong that European designers have simply ignored a lot of the purported standard in designing what is describe as CEN-compatible equipment. One European at the meeting in Reston said that the American efforts to understand and clarify the CEN document were helpful, and that if they are incorporated into an international standard, they will improve it. With so many parts of CEN obscure you could have different companies making their own interpretations and claiming it as CEN-compatible, but being incompatible with one another out on the road!

The N.Am Layer 7 work led by Peter Houser of Signal Processing has proceeded rapidly and is complete except for the possible handling of message fragmentation from Layer 2. Its main purpose is to put maximum functionality in the roadside equipment, allowing for a wide range of onboard equipment all the way from simple read-only account or registration identifier devices able to be built for cents all the way up to elaborate onboard computers costing thousands of dollars. Privacy and security is handled in the applications at Layer 7, not in the transponder itself, allowing both unencrypted and encrypted messages. Different amounts of memory and different interfaces are provided for, but the trnasponder is designed to be just “modem and memory on wheels.” A Resource Manager next to the reader (or ‘beacon’ the IEEE having adopted the European term) handles the different resources on the tag and handles operations with different back office applications. It is a switch between the reader and the various applications.

This approach is thought to offer much lower cost and give greater flexibility than the European, while taking advantage of the best parts of their work. Houser said that a successful system will have to take account of the fact that while hardware gets cheaper software keeps getting more expensive, and to limit the need to write special applications code for DSRC products.

IEEE has one more meeting and will wait for the fragmentation handling issue at ASTM to be resolved and then will ballot. It is still accepting people wanting to join the voting roll. USDOT suggested that the toll agencies might join with the manufacturers to support some ASTMv7 equipment testing and Ray Starsman of ITSA suggested the feds consider a ‘super-MDI’ a model deployment initiative fusing two or more regions and demonstrating interoperability.

Lee Armstrong heading up the whole ASTMv7 effort was however concerned about getting paid. As a consultant he ended the conference with “about $100” left in his USDOT budget and no more money in sight because of various highway funding impasses on Capitol Hill. (Contacts Rick Schuman ITSA 202 484 4543, Lee Armstrong ASTM work 617 261 7151 LRA@tiac.net Pete Houser IEEE work 619 679 6466 peter.houser@sps.globalus.com)