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Public Sector ITS Datum Workshop

Knoxville, Tennessee, March 16-17, 1998

Proceedings of the Breakout Group for GIS-T and Planning

Participants in the GIS-T and Planning breakout group:

Fred Latham, Viggen Corp., Knoxville, TN, moderator

Marvin Garland, Knoxville/Knox Co. MPC, Knoxville, TN

Steve Lewis, BTS, Washington, DC

David Siegel, GIS/Trans, Boston, MA

Wende O'Neill, BTS, Washington, DC

Kevin Little, Vanderbilt University, Nashville, TN

Kim Henry Begg, Knoxville/Knox Co. MPO, Knoxville, TN

The task of the GIS-T and Planning breakout group was to determine the possible utility of the ITS Datum across the public sector continuum from federal to local. The following qualitative observations help identify a number of issues that concern the agencies charged with implementing ITS.

Use of spatial data

The recurring issue concerning spatial data is that of the appropriate scale and resolution. For city planning and GIS-T applications, data with a resolution of ± 160 meters, is, of course, inappropriate. Conversely, modeling and planning at the state or regional level do not require data or datums with sub-meter accuracy.

Locational accuracy is imperative at the local level.
Data must be collected at the bottom level (i.e. local) and aggregated up rather than generated at the top (i.e. federal) level down.
The need for greater resolution is always application driven, with more exacting requirements at the local level.

Ambiguity

Public participation is extremely important for successful planning. Imprecise data can hinder public participation by prejudicing the public agencies acceptance of planning initiatives.

Precision is needed for public acceptance and participation.
Effects of ambiguity are application dependent; again, an artifact of the spatial extent of the area of operation.

Observations about operations and planning needs

Better information is needed for planning needs.
Planning needs should be considered during the design of data collection methods.
Emergency Management Systems (EMS) sites are now located with the use of Advanced Traffic Management Systems (ATMS) define planning data.
Issues - migration of legacy data into current specs and systems.
At state level, initial ITS deployment is chiefly for construction zones and service patrols, indicating less of a need for high accuracy.

Requirements for datum to be useful in GIS-T and Planning -- Observations

Node placement within a lane introduces uncertainty and, eventually, inaccuracy. For example, accuracy will be lost or altered whenever lanes are widened or whenever lanes are re-striped.
Support for interoperability is locally driven, with bottom up needs.
Milepost points must be viewed as reference points rather than datum points.
Arial coverage requirements are application driven -- e.g., data used for routing analysis, or for display purposes.
Events must be referenced to anchor sections rather than anchor points or datum points.

Obstacles to Interoperability

Guidelines should not be standards - local and state agencies are very concerned about unfunded mandates.
Lack of uniformity of the resolution of basemaps.
Datum should act as a framework for registration and possibly conflation.

Implementation Issues

Technologies are compartmentalized in various agencies. One department may be responsible for ITS implementation, another may house the GIS-T activities. Without an integrated, enterprise GIS capability, implementation of ITS initiatives like the ITS datum will languish.
Adoption of any new technology must overcome political hurdles, and the expense must be justified.
Implementation depends on public relations and education -- cost justification must be clearly expressed. Benefits of participation must be specifically articulated, based upon sound cost-benefit analysis. Business interests must be made clear.
Friction caused by top-down rather than bottom-up approach.
Implementation of standards or recommendations should come from AASHTO, which has an ITS committee, rather than from the federal level.