Federal Geographic Data Committee (FGDC); Public Comment on the Proposal To Develop the ``NSDI Framework Road Data Model Standard'' as a Federal Geographic Data Committee Standard

Federal Geographic Data Committee (FGDC); Public Comment on the Proposal To Develop the ``NSDI Framework Road Data Model Standard'' as a Federal Geographic Data Committee Standard

Federal Register Notice
July 8, 1998
Volume 63, Number 130

ACTION: Notice; Request for comments.

SUMMARY: The FGDC is soliciting public comments on the proposal to develop a ``NSDI Framework Road Data Model Standard.'' If the proposal is approved, the standard will be developed following the FGDC standards development and approval process and will be considered for adoption by the FGDC.

In its assigned federal leadership role in the development of the National Spatial Data Infrastructure (NSDI), the Committee recognizes that FGDC standards must also meet the needs and recognize the views of State and local governments, academia, industry, and the public. The purpose of this notice is to solicit such views. The FGDC invites the community to review the proposal and comment on the objectives, scope, approach, and usability of the proposed standard; identify existing related standards; and indicate their interest in participating in the development of the standard.

DATES: Comments must be received on or before July 25, 1998.

CONTACT and ADDRESSES: Comments may be submitted via Internet mail or by submitting electronic copy on diskette. Send comments via internet to: gdc-rdmod@www.fgdc.gov.

A soft copy version, on a 3.5 x 3.5 diskette in WordPerfect 5.0 or 6.0/6.1 format, along with one hardcopy version of the comments may be sent to the FGDC Secretariat (attn: Jennifer Fox) at U.S. Geological Survey, 590 National Center, 12201 Sunrise Valley Drive, Reston, Virginia, 20192.

SUPPLEMENTARY INFORMATION: Following is the complete proposal for the ``NSDI Framework Road Data Model Standard''.

Project Title: NSDI Framework Road Data Model Standard

Submitting Organization: FGDC Ground Transportation Subcommittee

Point of Contact: Bruce D. Spear, U.S. Department of Transportation, Bureau of Transportation Statistics (BTS), (202) 366-8870, bruce.spear@bts.gov


To provide a logical data model for identifying unique road segments which are independent of cartographic or analytic network representation. These road segments will form the basis for maintenance of NSDI framework road data (through transactions or other means), and for establishing links among road segments and attribute data.


In accordance with the FGDC Standards Reference Model, the NSDI Framework Road Data Model is being proposed under the classification of a data content standard. However, it also includes mandatory standards for assigning and reporting identification codes as well as voluntary guidelines for data collection under the classification of a process standard.

This standard will specify a conceptual model for identifying physical road segments that are temporally stable and independent of any cartographic representation, scale, level of detail or network application, and a process for combining the road segments to create topologically connected analytical networks. The model will include a set of locational descriptors for each road segment included in the NSDI framework road layer, and a format for a unique identification code to be assigned to each identified segment. The standard will also specify a process for assigning, modifying and recording road segment identification codes.

Guidelines for selecting and locating the end points of appropriate road segments will be included as an informative appendix. The user of the standard does not have to follow the guidelines to be in conformance with the standard.

The basic road data model can be extended to cover other transportation networks including railroads, commercial waterways, pipelines, and public transit guideways. Other network layers may require different process standards for assigning and recording identification codes. These additional process standards are not included as part of this initial standard.


There are currently no national standards for identifying, segmenting, or representing road segments in digital geo-spatial databases. Database developers segment road networks to satisfy their specific application needs; however, the specific segmentation scheme may not be appropriate for other applications. Furthermore, there is no standard approach for documenting the relationship between a digitized road segment and the physical road feature that it represents. Consequently, the exchange of attribute information between two different road databases representing the same geographic area is difficult, time consuming and error prone.

A national standard for identifying and documenting road segments will facilitate data exchange among different users by providing well defined, common reference segments that are tied to the physical road feature, rather than to any cartographic or network abstraction of that feature. Furthermore, the proposed standard road data model will allow users to create customized topological networks from the reference segments without modifying the properties of the reference segments themselves. This will facilitate transactional updates to framework road databases by allowing new road features to be added without changing existing road segments.

Development Approach

A Road Data Model Team will be assembled to review the technical development of the standard and to provide appropriate outreach to the transportation community. (See POTENTIAL PARTICIPANTS, below.)

An initial draft of the road data model will be prepared under contract, funded by BTS (in progress). The initial draft will be based, in large part, on the preliminary road data models emerging from the NSDI Framework Road Data Modeling Workshop, held at Wrightsville Beach, NC, in December 1997. These preliminary data models are compatible with the generic linear data model developed under the National Cooperative Highway Research Program (NCHRP) Project 20-27.

The initial draft will be reviewed by the Road Data Model Team and revised based on concerns and recommendations expressed by team members. Depending on the nature of the review comments, one or more meetings may be convened to resolve differences among the team. Team members will also be responsible for informing their constituencies about the road data model standard and for collecting and summarizing the requirements of their respective stakeholders groups.

The road data model development effort will be closely coordinated with NCHRP Project 20-27 (Phase 3), which focuses in the development of implementation guidelines for multimodal transportation location reference systems. It will also provide a focus for possible follow-up workshops to Wrightsville Beach.

Once there is general agreement among the Road Data Model Team that the model meets agreed-upon requirements, the model will be submitted for formal public review through the FGDC's Standards Development Process.

Development and Completion Schedule

  • Solicitation and selection of Road Data Model Team--May 1998.
  • Initial draft of road data model by BTS contractor--June 1998.
  • Review and revisions to road data model--summer and fall 1998.
  • At least one meeting of the full team will take place after the initial road data model has been delivered and distributed to team members.
  • Team members will be responsible for informing and soliciting feedback from their constituencies about the standards development effort through presentations at annual meetings, articles in newsletters, etc.
  • The road data model will be prototyped on one or more road databases to assess implementation and maintenance issues, requirements for additional tools, etc.
  • Revised draft of road data model prepared by BTS contractor and approved by majority of road data model team--December 1998
  • Road Data Model Standard submitted for public review through FGDC--January 1999
  • Informational presentations on road data model to be made at major transportation and GIS conferences, including TRB, GIS-T Symposium, etc.
  • Final Road Data Model Standard approved as FGDC standard-- June 1999.

Resources Required

Funding support for contractor to prepare initial road data model and to revise model in response to review comments will be borne by the Bureau of Transportation Statistics.

Participation on the Road Data Model Team will be on a voluntary basis. Time spent by team members to familiarize themselves with the NSDI framework and linear data models, review draft documents, participate in team meetings, and serve as liaison to their respective constituencies will be borne by each member's agency or organization. Some additional FGDC funding may be needed to support travel to meetings for some team members.

Potential Participants

Team members will include representatives from the FGDC Ground Transportation Subcommittee, Facilities Working Group, Base Cartographic Subcommittee, Cultural and Demographic Subcommittee, and Framework Focus Group. Additional representation will be sought from key transportation and spatial data stakeholders, including the Transportation Research Board (TRB) GIS-T Task Force, the Intelligent Transportation Systems (ITS) standards working group, the American Association of State Highway and Transportation Officials (AASHTO), the Open GIS Consortium (OGC) Transportation Work Group, NSGIC, NaCO, and other interested stakeholders.

Related Standards

There are a number of standards for roads and other transportation currently being promulgated by different stakeholders. In general these standards have been designed to meet the specific requirements of the stakeholder groups sponsoring their development, and do not generally satisfy the basic NSDI requirements for database sharing and transactional updating. Nevertheless, these standards will be investigated as part of this development effort to determine commonalities and opportunities for integration.

The ITS Standards and Protocol Subcommittee has proposed adoption of the Geographic Data Files (GDF) as its standard for digital road databases. This standard does not meet all of the requirements of the broader GIS for transportation (GIS-T) community, particularly with respect to location referencing.

The DIGEST/Vector Product Format standard is an interchange standard for spatial data used by the U.S. Department of Defense, NATO, and the Transportation Association of Canada. DIGEST/VPF. This standard, like GDF does not meet all of the requirements of the GIS-T community.

A draft Transportation Network Profile (TNP) was developed for the Spatial Data Transfer Standard (SDTS) several years ago, but was never submitted for formal adoption due to a number of unresolved issues. Adoption of a standard road data model may help resolve many of these outstanding issues, and lead to resumption of the SDTS TNP development.

A Ground Transportation Data Content Standard is being proposed to provide a common set of entity/attribute/domain definitions for transportation features. These two efforts will be closely coordinated, and the road data model will provide the foundation on which transportation features in the content standard will be defined.

ITS is also proposing the establishment of a national linear datum, consisting of well defined and accurately located control points from which linear measurements can be made along a road segment. The proposed road data model is compatible with the ITS linear datum. Every effort will be made during the development of the road data model to maintain this compatibility so that framework road segments can fully utilize the linear datum, if it is actually implemented.

Other Targeted Authorization Bodies

None at this time. However, depending on the acceptance of the proposed road data model by the transportation community, it may be appropriate to submit it to ANSI and ISO at a later date.

Dated: June 29, 1998.

Richard E. Witmer,
Chief, National Mapping Division.

[FR Doc. 98-18071 Filed 7-7-98; 8:45 am]