Stop Places
For EPIP stop data, the primary entity is the STOP PLACE. However, this entity inherits its properties through quite a deep hierarchy, and a basic knowledge of the hierarchy is required in order to have an accurate understanding of the model.
The top object in the inheritance tree is a ZONE, describing a generic two-dimension object. A ZONE may be defined by a GROUP OF POINTS belonging to the ZONE, and may also be defined as a geometric area, bordered by a polygon (based on the GML Linear Ring feature).
A ZONE may nest other smaller ZONEs (this nesting may be multilevel). This is expressed by the reflexive relationship on ZONE (so a STOP PLACE may include other STOP PLACEs).
A ZONE may be represented by a single POINT (by the Centroid attribute of a Zone attribute). A centroid point defines a special kind of point that can be used as a point reference to the ZONE itself. This is useful for representing flexible transport systems (where a stop is often a ZONE).
The second level of the hierarchy is the PLACE, which represents any significant place that a transport model may wish to describe, and for which the possibility of travel may exist between. A PLACE can be specialised variously into a TOPOGRAPHIC PLACE (a named city, town or region) with a wide extent, or a specific ADDRESSABLE PLACE having an ADDRESS that is either a ROAD ADDRESS, or a POSTAL ADDRESS.
A SITE ELEMENT specialises ADDRESSABLE PLACE to add accessibility (see ACCESSIBILITY ASSESSMENT) and other properties common to any place that may be navigated through by a passenger.
A SITE specialises SITE ELEMENT to provide a general description of common properties of a physically situated location, such as a station or point of interest, including its entrances, levels, equipment, paths, accessibility properties, etc. The SITE is refined by specific subtypes such as STOP PLACE, POINT OF INTEREST, PARKING, etc.. The basic elements making up a SITE are:
¾ SITE COMPONENT (not shown): an element of a SITE describing part of its structure, such as a platform, concourse, ticket hall, entrance hall forecourt, room, retail area, etc. These may be specialised in submodels. (QUAY and STOP PLACE ENTRANCE are examples shown above)
¾ LEVEL (not shown): an identified storey (ground, first, basement, mezzanine, etc.) within an interchange building or SITE on which SITE COMPONENTs reside.
¾ ENTRANCE (not shown): a physical entrance or exit to/from a SITE. Each type of site will have its own ENTRANCE TYPEs (E.g. STOP PLACE ENTRANCE, POINT OF INTEREST ENTRANCE, etc).
The STOP PLACE describes different aspects of a physical point of access to transport, such as a stop or station. For a complex interchange, such as a station, this includes all the component areas of the station: the entrances, concourses, platforms, the levels they are on, etc. It also allows detailed accessibility attributes to be recorded at both the element and the station level.
A STOP PLACE represents a physical stop or station. Note that a STOP PLACE is a distinct concept from the representation of the stop in a timetable – the SCHEDULED STOP POINT. The two can be linked using a STOP ASSIGNMENT.
Physically, the SCHEDULED STOP POINT may correspond either to a whole STOP PLACE or to a specific QUAY (i.e. a SCHEDULED STOP POINT is a “logical stop” whose spatial position is conventionally assigned to the centroid of the STOP PLACE for journey planning purposes). Conversely, a physical STOP PLACE or a QUAY may be viewed in different functional contexts and be subject to several different assignments to different SCHEDULED STOP POINTs (see 7.4.1-StopAssignment).
The physical point of access to transport is always a QUAY. STOP PLACE ENTRANCEs describe the internal and external entrances to the STOP PLACE.
Because they inherit an “includes” relationship from ZONE, STOP PLACEs can be organised into a hierarchy so describe clusters of transport interchanges, such as a paired rail and tube station.
QUAYs can be nested; this allows one to represent composite platforms with two or more sides or named sections. One can thus journey plan to any required level of detail.
STOP PLACE ENTRANCEs describe points at which a passenger can access a stop place, normally on foot – an ACCESS MODE can be used to identify other permitted modes of entries such as cycle or car. (STOP PLACE VEHICLE entrance ENTRANCEs can be external, for example the main entrance, or internal, for example from an entrance concourse to a platform.
Example from the Austrian NeTEx Profile:
