Consider the risk that draft ITS standards will not remain stable through further development when deciding whether to use them in an ITS deployment.
Hampton Roads, Virginia's experience with immature data-exchange standards for its Advanced Traveler Information System
At the time of the proposal, the contractor had a Beta version of a DATEX Toolkit product at version 8 of the standard. This standard is specifically an NTCIP Center-to-Center (C2C) DATEX-ASN draft ITS standard (NTCIP 2304: Application Profile for DATEX-ASN). Unfortunately, the draft base standard (ISO DATEX documents 14827, parts 1 and 2) had at the time over 100 international comments against it. This situation created uncertainty regarding the future direction of DATEX-ASN and reflected in part some of the contractor's difficulties with earlier versions of the standard.
- Retrofit to a mature standard rather than build to fit a developing standard. A decision was made that it was inappropriate to use ITS standards in the HRATIS, at least initially. Information on the practicability/ operational feasibility of the standards and protocols suggested for ATIS systems seemed to be very sparse. There was high risk in implementing a developing suite of standards now, as they were not finalized. As they mature, the risk will decrease. It is easier to retrofit to a mature standard than to build to fit a developing standard. Building to fit these standards as they developed would also prove impractical in terms of the cost.
- Find a work around non-proprietary solution. The primary reason for including DATEX-ASN in the proposal was to allow an open (i.e. non-proprietary) future interface of Regional Multi-modal Management System (RMMS) with HRATIS. This capability would still exist, but without utilizing DATEX-ASN. The contractor provided the simple interface details for exchanging data between the RIS and HRATIS, to Virginia DOT (VDOT). In effect, the same open interface could be used by the RMMS later.
- Identify standards that will provide the best fit for the project. Besides the DATEX-ASN protocol standard, the message sets and data dictionaries were still not mature. For data transfer to message sets, ATIS standards did not seem to fit best. Instead, Incident Management standards were found to provide the best fit. Therefore the data content for ATIS had to be changed to fit those standards.
As for protocols, DATEX and CORBA were the NTCIP protocols that existed for use in Center-to-Center data exchange. CORBA was more suited for enterprise wide data distribution and hence DATEX was considered for use in the beginning. Since DATEX was also found to be complicated, data exchange is currently carried out in an open format. DATEX V.8 was what the contractor used in the beginning, during development of the Data Fusion Engine. Using DATEX was perceived to be of high risk.
Overall, it was considered inappropriate to use draft ITS standards in the HRATIS at the time of the project. The practicability / operational feasibility of the standards and protocols suggested for ATIS systems seems to be very sparse. There is high risk in implementing a developing suite of standards now, as they are not finalized. As they mature, the risk will decrease. It is easier to retrofit a mature standard than to build to fit a developing standard. It also proves impractical in terms of the cost. Deciding not to use high-risk standards and finding a work-around non-proprietary solution could fulfill the intent of the initial proposal while reducing the risk of expensive modifications later if the standards were significantly changed.
Author: Demetsky, Michael J.; Park, B. Brian; Venkatanarayana, Ramkumar (UVA Center for Transportation Studies, Center for ITS Implementation Research)
Published By: Center for Transportation Studies, University of Virginia
Source Date: 10/1/2001
EDL Number: 13634
Other Reference Number: UVA-CE-ITS-03-1URL: http://ntl.bts.gov/lib//jpodocs/repts_te/13634.html
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