Latest Drafts

2001 May

Technical material on the data model is now available at the ESRI web site,

2001 March

Our most recent activity has been at the nuts and bolts level, linking UNETRANS to Arc8.1 — connecting the shell to the chassis, so to speak.  There's been some back and forth as a result, hence the prolonged silence from our end.  The packages are now quite different from what we presented in Redlands last December, and we invite your comment once more.

Reference network
Activities & incidents
Mobile objects
Linear referencing

Q: “Why are these separate units?  Don't they link together at some point?”
A: “The Arc8 geodatabase is the umbrella under which these exist.  The hooks are Arc8 Network Features and Objects.”

Earlier Drafts

Round 4 (2000 December, Redlands)

At the highest level, the model consists of 4 packages:
  1. transportation infrastructure — navigable objects
  2. assets
  3. vehicles
  4. business processes
Supporting packages deal with locators (including linear referencing), relationships and interfaces (collections of methods).  The best place to look for this draft is under the Redlands consultation — comments on the drafts are also available there.

Round 3 (2000 October)

In the third round we have unified the first two approaches, and implemented the model on a small test data set.

Round 2 (2000 September)

Over the last few months we have been gathering data models, requirements, feature descriptions, transportation entity labels, use cases and “nightmare pathologies” (difficult to model) from various users and previous efforts, including The first round was top-down construction of the model, considering the major entities and operations.  The second round was bottom-up, starting with the principal entities, objects, labels, spatial and operational relationships.

Round 1 (2000 August)

This is a conceptual overview that unifies the components that follow.  It was the first piece developed, and you'll find instances where the components differ from it.  In those cases the components reflect more recent thinking, and take precedence.

How You Can Help

To make the model most useful to a broad range of user needs, we're now looking for your contributions and feedback in the following areas:
  1. Application storyboards and scenarios — details on how you currently use (or would like to use) transportation data in specific applications, from data capture to output and decision.
  2. Difficult pathological cases — nightmare topologies that seem impossible to model (e.g. divided urban roads with parallel service roads and slip lanes linking them, prohibited turns, etc).
  3. Critique of the model above — try to capture your local geography using the model.
  4. Participation in the forum