1. vers. 20070524 national spatial data infrastructure training program An introduction to the Federal Geographic Data Committee (FGDC) Framework Data Standard (FDS) Part 7, the Transportation Model, with overview of the base model and the road system. Serving Transportation Data Through the NSDI The Framework Data Standard, Part 7: Transportation

2. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 1 Purpose of Lesson Purpose of this Lesson: To provide an overview and introduction to the Federal Geographic Data Committee (FGDC) Framework Data Content Standard (FDS) Transportation Theme and explain the tables, diagrams, controlled vocabularies, feature specifications and other references used within the standard

3. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 2 Learning Objectives After completing this lesson the student can: list the features of the Transportation Base model describe the role of each feature in characterizing a transportation system explain the use of Transportation Events, and the difference between Attribute Events and Feature Events, as well as point vs. linear events define the relationship of the Transportation Road Model to the Transportation Base Model comment upon the general characteristics of the models all four adopted transportation modes

4. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 3 Source Documents: The Standards Before beginning this lesson the reader is encouraged to download the following documents and have them ready for reference: Geographic Information Framework Data Standard, Part 7, Transportation Base, which we’ll call “FDS 7” Geographic Information Framework Data Standard, Part 7c, Road, which we will call “FDS 7c” Both of these documents may be found at: http://www.fgdc.gov/standards/standards_publications/

5. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 4 GML Implementations of the FDS The reader is also encouraged to download the GML implementations that implement the FDCS Transportation Model. Both full and simple schemas can be downloaded as a zip file from a link on: http://www.fgdc.gov/standards/projects/incits-l1-standards- projects/framework/models There are also validated schemas at http://frameworkwfs.usgs.gov/framework/schemas/gmlsf1/ Note: the schemas for BaseTransportation and Roads are of most interest to the material presented in this document.

6. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 5 Terms and Definitions A variety of terms are defined in Clause 5 of the Transportation Base Standard document (FDS 7) Please refer to this glossary if any questions arise about the meaning of terms Two terms of specific interest, which we will encounter later in this lesson and others, are: entity: a feature that has separate and distinct existence and objective or conceptual reality event: a mechanism for locating an attribute value or feature along a transportation feature

7. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 6 The FDS Transportation Theme (Part 7) The Transportation Theme is one of 7 Themes that comprise the FDS Context and descriptions may be found at http://www.fgdc.gov/training/nsdi-training-program/online- lessons#standardshttp://www.fgdc.gov/training/nsdi-training-program/online- lessons#standards under the heading “Topic: NSDI Data Themes” Objects in the FDS are based upon the Feature Model, and encoded as GML Features. The Transportation Base model and schema define parent classes for the more specialized components This course focuses on implementation of the Road network for the NSDI

8. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 7 Five Modes of Transportation There are Five modes of transportation modeled by the Framework Data Standard: Air, Road, Rail, Transit, and Inland Waterways Our examples will focus primarily on the Road network, for several reasons: the Transportation Theme is a large model, but similar principles apply to all of it this document is a guide to assist implementers, not a comprehensive reference the road model is fairly straightforward, so makes a good introductory example road network data are voluminous, and useful for many applications

9. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 8 Review What are the five modes of transportation supported by the Framework Data Standard? Air Road Rail Transit Inland Waterways

10. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 9 FDCS Transportation Theme Schemas Recall from Module 2 that there are different versions of GML (comment at end of Module 2) There are also different versions of the FDS Transportation Theme Schemas Two GML schemas for the Transportation Theme have been defined: one for Full GML, and one for the Simple Features Profile of GML, GML3L0 This lesson focuses on the Simple Features version

11. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 10 Transportation Base Model The concepts and definitions in the Transportation Base Model are the basis of object models for each of the five modes of transportation The Transportation Base Model defines the Transportation Feature (TranFeature) object. In addition to this, there are two main parts or submodels within the Transportation Base Model: the Transportation Segmentation Model, and the Transportation Event Model

12. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 11 Transportation Feature Model The Transportation Theme supports a Feature Model, derived from the ISO General Feature Model, and embodied in the TranFeature object.

13. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 12 Things to Note About TranFeature TranFeature inherits all properties from the abstract Feature of the General Feature Model Properties of TranFeature worth noting: TranFeature is nearly the same as the ISO Feature; only one property has been added: lastUpdateTime TranFeature can be instantiated; it is not abstract TranFeature is subclassable  the models for all modes of transportation in the FDS (Road, Rail, …) include classes built upon (i.e., that are subclasses of) TranFeature  users can also define their own TranFeature subclasses

14. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 13 Transportation Segmentation Model The Transportation Segmentation Model describes the topology and scale of the transportation network. The Segmentation Model is built upon three kinds of Transportation Feature: paths (“TranPath”) that traverse a series of … segments (“TranSeg”) that are connected by … points (“TranPoint”) These three feature types and their topological relationships define all possible movements through a transportation system.

15. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 14 Segmentation Model Classes Source: FDS Part 7, Figure 3 This (annotated) UML description of the Transportation Segmentation Model shows that TransSeg, TranPoint, and TranPath are all subclasses of TranFeature, and that a TranPath consists of an aggregation of TranSegs. aggregation subclass

16. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 15 Review What three kinds of Transportation Feature make up the Transportation Segmentation Model? - paths (TranPath) that traverse a series of … - segments (TranSeg) connected by … - points (TranPoint)

17. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 16 TranSeg A TranSeg is the transportation feature class that defines segments in the FDCS Transportation Model TranSeg is an abstract Feature: i.e., instances of TranSeg itself are not allowed, only of classes that inherit from it, such as:  RoadSeg - road network segment  RailSeg - railroad transportation segment  HydroSeg - water transportation segment  AirSeg - air transportation segment  TransitSeg - transit segment a TranSeg instance always represents a segment of some physical component of a transportation network.

18. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 17 TranPoint: the Connector TranPoint plays one and only one role in the FDCS Transportation Model: it provides the topological connection between TranSegs. “It is …recommended that each TranSeg in a transportation network have exactly one start TranPoint, and one end TranPoint.” [FDS Part7] TranPoint connects TranSegs TranPoints can connect any kinds of TranSeg, whether of the same or different concrete classes TranPoints do not represent physical entities, just connection information TranPoint is not abstract: it can be instantiated - this supports multimodal connection (e.g., road to rail connections)

19. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 18 Using TranPoints TranPoints are intended only to connect TranSegs, and should not be used to represent real-world entities For example, TranPoints on a road network should not represent intersections, even though they may be located at intersections

20. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 19 The figure below shows a TranSeg bounded by two TranPoints, A and B Points C and D represent some real-world entity, one on and one off the segment C and D may be represented as point features with no geometry, but they should not be represented as TranPoints The locations of C and D along the TranSeg can be specified via an event, a topic to be discussed later in this lesson, and in D’s case, an offset Proper Use of TranPoint Source of diagram and analysis: FDS Part 7 Figure 4

21. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 20 Definition: TranPath TranPath: a collection (formally, an ordered array) of TranSegs and the TranPoints that connect them TranPath is the fundamental means of modeling a route, including administrative routes (e.g., U.S. 101) multimodal routes: a single TranPath may include multiple kinds of TranSegs: e.g., transit, rail, and waterway different paths can include the same segments, e.g., in cases where state or county routes traverse the same section of road

22. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 21 Properties of Transportation Features Like other Features, TranFeatures may have properties Like other Features, the values of these properties may be literal values (numbers, text strings, booleans) Features in their own right (which have their own properties)`

23. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 22 TranSeg Value Properties A property of a TranSeg that is a value applies to the entire TranSeg, not just part of it Mandatory properties of a TranSeg include: length of the segment status character string  e.g., segment is closed, under construction, open, …

24. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 23 TranSeg Feature Properties A Feature property of a TranSeg, like a value property, applies to the entire TranSeg One important Feature property is the geometry of the TranSeg Geometry of a segment is always modeled as a GML Curve. Curve, like Feature, is associated with a substitution group

25. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 24 TranSeg Geometry The geometry property is optional for TranSegs A TranSeg may have multiple geometries, each for a different application e.g., for representation at different scales If the Simple Features model is used to represent the segment, the GML Curve used to model it must be implemented as a line string (polyline). the Full GML model provides more varied curve descriptors

26. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 25 Other TranSeg Properties Table 1 in FDS Part 7 details the properties for TranFeatures, TranSegs, TranPaths, and TranPoints This table indicates whether the properties are mandatory how many instances of the property are allowed (either just one or an unlimited number) The table of properties defines a data dictionary, an essential component of semantically well-defined systems

27. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 26 TranPath Geometry TranPath includes an aggregate of TranSegs, in the property “segment” TranPath has its own geometry - in concept the combined geometries of its TranSegs TranPath’s own geometry might be simpler than the combined segment geometries TranPath’s own geometry is modeled as a GM_MultiCurve, which allows for: discontinuities in the path a variety of ways to express the geometries of its different parts

28. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 27 TranPath UML The UML model of TranPath shows its inheritance from TranFeature, as well as the aggregate of TranSegs it represents, and its own, optional geometry property Source: FDS 7, Fig. 6

29. vers. 20070524 national spatial data infrastructure training program Transportation Event Model

30. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 29 Transportation Events The means of identifying the location of features or characteristics on a segment of the transportation network is called an event This terminology is used throughout the transportation industry Practical systems use events to describe the locations of characteristics, conditions, and non-network features (e.g., signs, signals) that are part of the transportation system

31. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 30 Transportation Event Model An Event in the FDS Transportation model is a data object that identifies the location of attributes or entities on a TranSeg or a TranPath Like the Segmentation Model discussed above, the Event Model can be applied in various ways depending upon the data the tools and applications that the local transportation information system supports standard practice at the data modeler’s institution

32. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 31 Transportation Event Class The TranEvent class embodies the elements of the FDS Transportation Event Model TranEvent inherits from TranFeature, and is abstract

33. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 32 TranEvent TranEvent: a mechanism for locating an attribute value or feature along either a TranSeg or a TranPath. A transportation feature is one of the properties of the TranEvent - it specifies where the attribute value or located feature occurs the transportation feature property is called LocatingFeature LocatingTranFeature is either a TranSeg or a TranPath Events can be attributes or Features; accordingly, there are two subclasses of TranEvent: AttributeEvent FeatureEvent Feature event has a property whose value is the Feature it locates; its name is linearlyLocatedFeature.

34. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 33 Tran Event and Offspring are Abstract TranEvent and its offspring AttributeEvent and FeatureEvent cannot be instantiated they are abstract like TranSeg Instantiable subclasses are either of a point or linear type Four instantiable classes inherit from AttributeEvent and FeatureEvent: PointAttributeEvent PointFeatureEvent LinearAttributeEvent LinearFeatureEvent

35. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 34 Transportation Event Model - UML This UML diagram shows the relationships among the TranEvent family Note that the point and linear events, the concrete classes in this model, are the only ones that have position properties. The point events have a single position property; the linear events have a start and end position. Source: FDS 7, Fig. 6

36. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 35 Review Q: Can TranEvent be instantiated? A: No, it is abstract Q: Can AttributeEvents and FeatureEvents, which are subclasses of TranEvent, be instantiated? A: No, they are also abstract Q: What concrete TranEvent classes have been defined? A: PointAttributeEvent, LinearAttributeEvent, PointFeatureEvent, LinearFeatureEvent

37. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 36 Using TranEvents If a feature or value property is constant and applies to an entire TranSeg or TranPath, it should be modeled as a property of the segment or path itself E.g., width if it is constant, or geometry If a feature or value property can change along a TranSeg or TranPath, or is present at only one location, an event should be used to document its position or linear extent on the locating feature E.g., speed limits (linear value), signs (point feature) Events can be used to document changes in physical aspects of the segment or path, such as curb material or curb lateral offset from the segment or path

38. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 37 TranEvent Data Dictionary The properties for transportation events may be found in the Data Dictionary in FDS Part 7, Table 2 Note that most of the properties are mandatory, and only one is allowed per instance An exception is the LocatingTranFeature, the segment or path along which the event is positioned - such a feature may be associated with multiple events

39. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 38 Linear Reference Systems Position on a one-dimensional path is specified in terms of distance from a specified point (the origin) on the path. The position is expressed in terms of measures in a Linear Reference System (LRS) An LRS consists of the origin, and a distance measure for expressing the offset or displacement from the origin. Linear transportation features and the curves that depict their geometry are oriented: location is measured as distance from origin the location consistently increases in one direction, and decreases in the other. the linear features are said to come from their starting point and extend to their endpoint

40. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 39 Linear Reference Systems - 2 Fundamental point: there are many units in which distance can be measured, and infinitely many points of origin along any line or curve. This course material assumes that the student is familiar with Linear Reference Systems For more information, please refer to Appendix B of FDCS 7, page 22

41. vers. 20070524 national spatial data infrastructure training program Application of the Roads Model Road System Model

42. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 41 Reference: FDS Part 7c - Roads The student is encouraged to download the Road System part of the FDS from http://www.fgdc.gov/standards/standards_publications/ the document is entitled “Part 7c, Transportation - Road, FGDC-STD-014.7c-2008” the document will be referred to as FDS Part 7c, or simply FDS 7c The remainder of this lesson will refer extensively to this document

43. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 42 Terms and Definitions Terms and definitions for the Transportation Road Model may be found in Section 2 of FDS part 7a It will be helpful for the student to briefly read the following definitions: anchor section (NOTE: these state the official surface length of a road segment [NCHRP 20-27(2)]) equivalence relationship (between road points) equivalence relationship (between road segments)

44. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 43 Road System The transportation road model has three main components: Road segmentation model Road event model Linear reference model (See Slide 48xxx of Module 3, or Annex B of the Transportation Base Model document [FDCS 7a]) The road segmentation and event models build upon the transportation base segmentation and event models - and inherit their semantics and use Thus roads are a fairly straightforward extension of the Transportation Base Model

45. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 44 Road Segmentation Model The Road Segmentation Model closely reflects the Transportation Base Model. The primary objects are: road segments (RoadSeg) road points (RoadPoint) road paths (RoadPath) These inherit from and fill equivalent roles to their counterparts in the Transportation Base Model The properties of road system objects are listed in Table 1 of FDS Part 7c

46. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 45 Road Segmentation Model UML Note that the only difference in properties between the base and road segmentation models is the addition of anchor points and anchor sections Source: FDS Part 7c, Figure 1

47. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 46 Use of Road Model Objects The semantics and therefore the appropriate use of the Road Model objects RoadSeg, RoadPoint, and RoadPath are essentially the same as for their Transportation Base equivalents Thus the student has already been introduced in some depth to the Road Model

48. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 47 Anchor Points and Anchor Sections The Road segmentation Model differs from the Transportation Base segmentation model in that it incorporates the notion of anchor points and anchor sections An anchor point represents a physical location in the the real world that can be identified unambiguously The location of a Road Point is to be taken as its measured, real-world position An anchor section represents the section of road between two anchor points the anchor section states the official length of the road section the anchor points at its termini are the official positions where the section stops and starts

49. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 48 Road Segment Equivalence Different organizations might have different names or different models for the same real-world entity Equivalencies like this can be indicated by using the “from” and “to” role names for RoadPoints and RoadSegs, inherited from the Base Transportation Features Equivalencies are discussed at length in Annex A of FDS Part 7 We mention them here because they apply in particular to road modeling situations Source: FDS Part 7, Annex A Models from different organizations can be integrated by designating points and between them as equivalent. In the diagram, points A and B are anchor points, and section 1-1 is equivalent to the combination of sections 2-1 and 2-2

50. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 49 The Road Event Model The Roads part of the FDS Transportation Theme includes an event model that is much the same as the generic Transportation Event Model The biggest difference between Road Events and the Transportation Events is the size of the data dictionary The data dictionaries for RoadAttributeEvent and RoadFeatureEvent may be found in FDS Part 7c, Tables 2, 3, and 4

51. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 50 Road Event As in the Transportation Base event model, RoadEvent and its immediate offspring (RoadAttributeEvent and RoadFeatureEvent) are abstract Their offspring, which model point and linear attributes or events, are concrete The following slides contain UML diagrams for the Road Event model

52. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 51 RoadAttributeEvent - UML Source: FDS Part 7c, Figure 4 Note that the Road Event Model is identical in form to the generic TranEvent model.

53. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 52 RoadFeatureEvent - UML Source: FDS Part 7c, Figure 5 As in the the generic TranEvent model, only the Point and Linear events are concrete. As with TranEvent, point events apply to one point location on the LocatingRoadFeature. Linear events apply to a segment.

54. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 53 RoadFeatureEvent Semantics Note that for point or linear RoadFeatureEvents, only the location information is part of the event object itself All the feature’s attributes remain with the feature Moreover all the feature’s attributes apply to the event For a linear event, the feature’s attributes apply to the entire linear segment with which the event is associated Linear events may be linear objects, e.g. guardrails

55. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 54 Codelists for Event Type The Event Model supports many feature types: see the codelists for RoadLinearEventType and RoadPointEventType, FDS Part 7c, Tables 3 and 4

56. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 55 Example: Analyzing a Road Network See Annex A, FDS Part 7c: how to analyze and express a small road network using the FDS Transportation Model Shows how to use both the Road Event model and the Road Segmentation model

57. vers. 20070524 national spatial data infrastructure training program Brief comments about Rail, Transit, and Waterways Application of the Roads Model The Other Parts of the Transportation Model

58. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 57 Remaining FDS Transportation Models The FDS Transportation Theme nominally includes five parts, or transportation modes: Road Rail Transit Waterways Air - however the model for air transportation has not been adopted as of August, 2010 Brief comments on the other transportation modes follow

59. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 58 Brief Sketch: Rail Model The FDS Rail Model is similar to the Roads Model, but a bit more complex The Rail Model includes a segmentation model and an event model, both of which closely mirror the structure of the Road Model and the Transportation Base However, the Rail Model has additional features and properties that describe the ownership of various facilities, including the rail itself, that are part of the system

60. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 59 Brief Sketch: Transit Model The FDS Transit Model is considerably more complex than the models for the other modes of transportation. Transit does include a TranPath in its feature model The class that inherits from TranSeg is ConnectionSeg, which has additional properties and semantics related to stops, and incorporates issues of accessibility There is no TranPoint subclass, but a number of features subclassed directly from TranFeature The Data Dictionar reflects issues involving ownership and various aspects of transit systems’ operations

61. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 60 Brief Sketch: Waterways Model The Waterways transportation model is simple relative to the others The Waterways Model does not subclass TranPath The Waterways subclass of TranSeg is SailingLine The subclass of TranPoint is MileMarker A subclass of TranFeature models the area in a waterway bounded by specified depth contour There is no Waterways Event Model

62. national spatial data infrastructure training program The Framework Data Standard, Part 7: Transportation 61 Harmonizing Your Data with the FDS Transportation Model Next Lesson