Transportation schema
^^^^^^^^^^^^^^^^^^^^^

For the realisation of transportation objects two tables are provided:
TRAFFIC_AREA and TRANSPORTATION_COMPLEX.

**TRAFFIC_AREA**

Next to the common attribute triple *class*, *function* and *usage*
traffic areas can store information about their *surfaceMaterial*. In
the UML model this attribute is specified as *gml:CodeType* which makes
an additional \_CODESPACE column necessary. The representation of
geometry is handled by foreign keys LODx_MULTI_SURFACE_ID (with 2 ≤ x ≤
4). The aggregation relation between a transportation complex and the
corresponding traffic areas results from the foreign key
TRANSPORTATION_COMPLEX_ID. The foreign key OBJECTCLASS_ID indicates
whether a tuple represents a *TrafficArea* (value 47) or an
*AuxiliaryTrafficArea* (value 48) feature. If a CityGML ADE is used that
extends any of the two classes *TrafficArea* or *AuxiliaryTrafficArea*,
further values for OBJECTCLASS_ID may be added by the ADE manager. Their
concrete numbers depend on the ADE registration (cf. :numref:`ade_manager_plugin_registration_chapter`).

**TRANSPORTATION_COMPLEX**

As shown in the UML diagram, every traffic area object may have the
attributes *class*, *function* and *usage*. For differentiation between
the subclasses an OBJECTCLASS_ID column is used again:

-  42 (*TransportationComplex*)

-  43 (*Track*)

-  44 (*Railway*)

-  45 (*Road*)

-  46 (*Square*)

If a CityGML ADE is used that extends any of the classes named above,
further values for OBJECTCLASS_ID may be added by the ADE manager. Their
concrete numbers depend on the ADE registration (cf. :numref:`ade_manager_plugin_registration_chapter`).

In the coarsest level transportation complexes are modelled by line
objects. The corresponding column is called LOD0_NETWORK of geometry
type *MultiCurve* in Oracle and *MultiLineString Z* in PostGIS. Starting
form LOD1 the representation of object geometry is handled by foreign
keys LODx_MULTI_SURFACE_ID (with 1 ≤ x ≤ 4).

.. figure:: ../../media/citydb_schema_transportation_diagram.png
   :name: citydb_schema_transportation_diagram
   :align: center

   Transportation database schema