ISO 17572-3:2015

INTERNATIONAL ISO
STANDARD 17572-3
Second edition
2015-01-15
Intelligent transport systems (ITS) —
Location referencing for geographic
databases —
Part 3:
Dynamic location references
(dynamic profile)
Systèmes intelligents de transport (SIT) — Localisation pour bases de
données géographiques —
Partie 3: Localisations dynamiques (profil dynamique)
Reference number
©
ISO 2015
© ISO 2015
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms and attribute codes . 4
4.1 Abbreviated terms . 4
4.2 Attribute codes . 5
5 Objectives and requirements for a location referencing method . 6
6 Conceptual data model for location referencing methods . 6
7 Specification of dynamic location references . 6
7.1 General specification . 6
7.2 Location referencing building blocks . 7
7.2.1 General. 7
7.2.2 Points . 7
7.2.3 Attributes . 8
7.2.4 Next-point relationship .15
7.2.5 Attribute type list .15
8 Encoding rules .15
8.1 General .15
8.2 General point representation and selection rules .21
8.3 Location reference core encoding rules .21
8.3.1 Location selection .21
8.3.2 Location reference core point selection .22
8.3.3 Core point selection — Location points.22
8.3.4 Core point selection — Intersection points .23
8.3.5 Core point selection — Routing points .25
8.3.6 Intersection point attributes .27
8.3.7 Routing point attributes .28
8.3.8 Location reference core encoding parameters .29
8.4 Location reference extension encoding rules .29
8.4.1 General.29
8.4.2 Location reference extension necessity rules .30
8.4.3 Location reference extension point selection rules .30
8.4.4 Location reference extension encoding parameters .31
8.5 Coding of point locations.32
8.6 Coding of area locations .32
8.6.1 Coding of explicit area .32
8.6.2 Coding of implicit area .34
9 Logical data format specification .37
9.1 General .37
9.2 Data model definition.37
9.2.1 General.37
9.2.2 General data model .38
9.2.3 Linear location data model .38
9.2.4 Implicit area data model .39
9.2.5 Explicit area data model .40
Annex A (informative) Dynamic location reference, TPEG2 logical structure .41
Annex B (normative) Dynamic location reference, TPEG2 binary representation .58
Annex C (normative) Dynamic location reference, TPEG2 XML representation .66
Annex D (informative) Coding guidelines for dynamic location references .73
Annex E (informative) Compressed data format specification .79
Bibliography .103
iv © ISO 2015 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 204, Intelligent transport systems.
This second edition cancels and replaces the first edition (ISO 17572-3:2008), which has been technically
revised. It also incorporates Technical Corrigendum ISO 17572-3:2008/Cor1:2009.
ISO 17572 consists of the following parts, under the general title Intelligent transport systems (ITS) —
Location referencing for geographic databases:
— Part 1: General requirements and conceptual model
— Part 2: Pre-coded location references (pre-coded profile)
— Part 3: Dynamic location references (dynamic profile)
Introduction
A location reference (LR) is a unique identification of a geographic object. In a digital world, a real-
world geographic object can be represented by a feature in a geographic database. An example of a
commonly known location reference is a postal address of a house. Examples of object instances include
a particular exit ramp on a particular motorway, a road junction, or a hotel. For efficiency reasons,
location references are often coded. This is especially significant if the location reference is used to
define the location for information about various objects between different systems. For intelligent
transport systems (ITS), many different types of real-world objects will be addressed. Amongst these,
location referencing of the road network, or components thereof, is a particular focus.
Communication of a location reference for specific geographic phenomena, corresponding to objects in
geographic databases, in a standard, unambiguous manner is a vital part of an integrated ITS system,
in which different applications and sources of geographic data will be used. Location referencing
methods (LRMs, methods of referencing object instances) differ by applications, by the data model used
to create the database, or by the enforced object referencing imposed by the specific mapping system
used to create and store the database. A standard location referencing method allows for a common
and unambiguous identification of object instances representing the same geographic phenomena in
different geographic databases produced by different vendors, for varied applications, and operating on
multiple hardware/software platforms. If ITS applications using digital map databases are to become
widespread, data reference across various applications and systems has to be possible. Information
prepared on one system, such as traffic messages, has to be interpretable by all receiving systems. A
standard method to refer to specific object instances is essential to achieving such objectives.
Japan, Korea, Australia, Canada, the US, and European ITS bodies are all supporting activities of location
referencing. Japan has developed a Link Specification for VICS. In Europe, the RDS-TMC traffic messaging
system has been developed. In addition, methods have been developed and refined in the EVIDENCE
and AGORA projects based on intersections identified by geographic coordinates and other intersection
descriptors. After the publication of the first edition of this International Standard in 2008, TPEG had
changed to TPEG2. Modifications related to this change are captured in this second edition. In the US,
standards for location referencing have been developed to accommodate several different location
referencing methods.
This International Standard provides specifications for location referencing for ITS systems (although
other committees or standardization bodies can subsequently consider extending it to a more generic
context). In addition, this version does not deal with public transport location referencing; this issue will
be dealt with in a later version.
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this part of ISO 17572 can involve the use of a patent concerning procedures,
methods and/or formats given in this part of ISO 17572 in Clauses 8 and 9 and Annexes A, B, and C.
ISO takes no position concerning the evidence, validity, and scope of this patent right.
The holder of this patent right has ensured ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In
this respect, the statement of the holder of this patent right is registered with ISO. Information can be
obtained from:
vi © ISO 2015 – All rights reserved

Panasonic, OBP Panasonic Tower, 2–1-61 Shiromi, Chuo-ku, Osaka, 540–6208,
Japan
Matsushita Electric Co., Ltd.
Blaupunkt GmbH Robert-Bosch-Str. 200, 31139 Hildesheim, Germany
Siemens AG Philipstr. 1, 35576 Wetzlar, Germany
Tele Atlas NV Reitscheweg 7F, 5232 BX ‘s-Hertogenbosch, Netherlands
Toyota Motor Co. (et al.) 1 Toyota-Cho, Toyota City, Aichi Prefecture 471–8571, Japan
INTERNATIONAL STANDARD ISO 17572-3:2015(E)
Intelligent transport systems (ITS) — Location referencing
for geographic databases —
Part 3:
Dynamic location references (dynamic profile)
1 Scope
This International Standard specifies location referencing methods (LRMs) that describe locations
in the context of geographic databases and will be used to locate transport-related phenomena in an
encoder system as well as in the decoder side. This International Standard defines what is meant by such
objects and describes the reference in detail, including whether or not components of the reference are
mandatory or optional, and their characteristics.
This International Standard specifies two different LRMs:
— pre-coded location references (pre-coded profile);
— dynamic location references (dynamic profile).
This International Standard does not define a physical format for implementing the LRM. However, the
requirements for physical formats are defined.
This International Standard does not define details of the location referencing system (LRS), i.e. how the
LRMs are to be implemented in software, hardware, or processes.
This part of ISO 17572 specifies the dynamic location referencing method, comprising
— attributes and encoding rules
— logical data modelling
— TPEG physical format specification for dynamic location references,
— coding guidelines for dynamic location references;
— compressed data format specification.
It is consistent with other International Standards developed by ISO/TC 204 such as ISO 14825.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 17572-1, Intelligent transport systems (ITS) — Location referencing for geographic databases — Part 1:
General requirements and conceptual model
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17572-1 and the following apply.
3.1
bearing
angle between a reference direction and the direction to an object measured clockwise
Note 1 to entry: Unless otherwise specified, the reference direction is generally understood to be geographic north.
3.2
connection angle
CA
difference between side road bearing (3.23) and bearing (3.1) at a point
3.3
connection point
location point captured in the location reference core, which forms the start point of a path external
to the location
Note 1 to entry: Connection points are used to connect a location reference extension to a location reference core and
to connect linear locations to form a subnetwork. The connection point is identified using its connection point index.
Note 2 to entry: The connection point index is implicitly defined by the order of the points in a location reference.
3.4
connectivity
status of being topologically connected
Note 1 to entry: In a graph, two or more edges are said to be connected if they share one or more nodes.
3.5
coordinate pair
set of two coordinates (one longitude value and one latitude value), representing a position on the earth
model
Note 1 to entry: Within the scope of this International Standard, the earth model is embodied by ITRS and by
ITRF coordinates.
3.6
core point
CP
point belonging to the location reference core
3.7
destination location
location to be used as the end location of a journey for a route guidance application
3.8
extension point
EP
point belonging to the location reference extension
3.9
great circle
circle on the surface of a sphere that has the same circumference as the sphere
Note 1 to entry: The connection between two points on a sphere along the great circle passing through the said
two points is the shortest connection (airline distance or distance ”as the crow flies”).
2 © ISO 2015 – All rights reserved

3.10
intersection point
IP
core point representing an intersection, located at places where the road section signature at the
location changes
Note 1 to entry: The intersection point is one of the three defined core point types.
3.11
location point
LP
core point that bounds or is located on the location
Note 1 to entry: Location points can coincide with intersection points or routing points. The start and the end of
the location are always represented by a location point. Additional intermediate location points can be created to
represent the shape of the location. The location point is one of the three defined core point types.
3.12
location reference core
point or set of points that is available in any location reference
Note 1 to entry: The rules in Clause 8 control the data to be stored in the location reference core.
3.13
location reference extension
additional point or set of points, not belonging to the location reference core, available in a location
reference under special conditions
Note 1 to entry: The rules in Clause 8 specify the conditions under which a location reference extension is to be
used and control the data to be stored in a location reference extension.
3.14
next point
point that is directly (topologically) connected to a given point, in a direction that is defined by the
defined direction of the location
Note 1 to entry: A point can have zero or more next points.
3.15
next point relation
ordered pair of points (A, B) for which a direct connection exists from A to B along the path of the
referenced location
Note 1 to entry: In the road network, a direct connection between points A and B exists when point B can be
reached from point A via part of the road network, without visiting intermediate points in the location reference.
This excludes points connected in a GDF graph via a node representing an intersection-not-at-grade. Such points
are not considered to be directly connected.
3.16
parallel carriageway indicator
non-negative integer which indicates if a road segment contains more than one carriageway in parallel
in the direction of interest, and how many
3.17
precise geometry description
shape along the location, coded on the most detailed level of the digital map, lying in a corridor with a
defined perpendicular distance to the great circle connection between two successive points on a location
3.18
road descriptor
full road number, or a significant substring of the official road name
Note 1 to entry: The road descriptor is ideally three to five characters in length.
3.19
road network location
location which has a one-dimensional and continuous structure, being part of a road network
Note 1 to entry: It is a continuous stretch of that road network as realized in the database, which can cover
different roads, and can be bounded on either side by an intersection. Alternatively it can be bounded on either
side by a position on a road.
3.20
road section signature
road signature
value of the attribute quadruple {functional road class, form-of-way, road descriptor, driving direction}
3.21
routing point
RP
point used to reconstruct the location by route calculation
Note 1 to entry: RPs are intended to allow point-based matching to the map database of the end user. When such
an RP match is found, the location then can be further reconstructed using the connectivity of the road network
as represented in the map database of the end user. The routing point is one of the three defined core point types.
3.22
side road section
road section which is not part of the location to be referenced, but connected to it via an at least
trivalent junction
3.23
side road bearing
bearing of the side road section
3.24
side road direction
driving direction of the side road section
3.25
side road signature
road section signature of a side road section
3.26
status location
location to be used to position location-based status information
EXAMPLE A location for speed limit information or traffic level information.
4 Abbreviated terms and attribute codes
4.1 Abbreviated terms
AGORA Implementation of Global Location Referencing Approach
(Name of a European project 2000–2002)
DLR dynamic location reference (also known as DLR1 because this is the first LRM under
dynamic profile)
4 © ISO 2015 – All rights reserved

GCId generic component identifier
GDF Geographic Data Files (data model, data specification, and exchange standard for geo-
graphic data for road transport applications)
ISO International Organization for Standardization
ITRF International Terrestrial Reference Frame
ITRS International Terrestrial Reference System
ITS intelligent transport system
LR location reference
LRM location referencing method
LRS location referencing system
NLR network location reference
RDS Radio Data System (digital data channel on FM subcarrier)
RFU Reserved for Future Use
SSF Syntax, Semantics, and Framing Structure (TPEG ISO/TS 18234-2)
TMC Traffic Message Channel [system for broadcast of (digitally encoded) traffic messages
on RDS]
UML Unified Modelling Language
VLC Variable Length Coding
XML Extensible Markup Language
4.2 Attribute codes
AFR accessible for routing flag
BR bearing
CA connection angle
CPI connection point index
DCA distance measure CA
DD driving direction
DMB distance measure bearing
DSF destination flag
FC functional road class
FCM functional road class minimal
FW form of way
IT intersection type
PCI parallel carriageway indicator
PD point distance
PDM D (attribute to measure distance on shapes)
perp-max
RD road descriptor
RDI road descriptor of intersection
RP routing point
SNI subnetwork index
5 Objectives and requirements for a location referencing method
For details, see ISO 17572-1:2014, Clause 4.
For an inventory of location referencing methods, see ISO 17572-1:2014, Annex A.
6 Conceptual data model for location referencing methods
For details, see ISO 17572-1:2014, Clause 5.
For examples of conceptual data model use, see ISO 17572-1:2014, Annex B.
7 Specification of dynamic location references
7.1 General specification
Dynamic location referencing is also known as the AGORA-C method and relies on specific attributes
that are mostly available in current digital map databases. Consequently, this LRM is adequate for LRSs
that have a physical format specification based on GDF. The method relies on real-time access by the
software to the original or translated values of the relevant attributes from its own digital map. This
LRM will also be called “on-the-fly referencing” because the location reference code can be immediately
discarded after internal definition of the location has been decoded. The dynamic location referencing
concept is designed to compensate for differences that might exist between the map used at the sending
system (the encoding side) and the map on board the receiving system (the decoding side). Such map
differences can be caused by the receiving system using an older map data set of the same supplier, or
vice versa, or the receiving system using a map data set from a different supplier.
Dynamic location referencing is often not as compact as pre-coded location coding. However, it is generally
accepted that if dynamic location reference codes can on average stay within 50 bytes for problem and
status locations, this would be acceptable in terms of bandwidth occupation. The specification focuses
on LRSs for two purposes, and hence provides two building blocks.
— Location reference core
The location reference core is applicable to problem and status locations, e.g. road traffic messages.
The location reference core is intended to provide location information much like ALERT-C location
[10]
referencing for which this specification actually intends to provide a lightweight dynamic
location reference (not requiring pre-coding and the use of location tables). The location reference
core prepares a function for additional robustness called precise geometry description in cases
where a lack of information elements in the decoder’s map is expected or under conditions defined
in the following clause.
6 © ISO 2015 – All rights reserved

— Location reference extension
The location reference extension is applicable to use in routing to destination locations, i.e. the
location of interest is to be used as the destination of a route guidance application. The location
reference extension augments the location reference core to an extended location reference, in
which the location reference extension is provided to ensure that a path from the location of interest
to the nearest part of the road network defined in the location reference core exists.
A dynamic location reference is constructed as a set of information elements, which consists of points
and related attributes. All points in both building blocks of the location reference (location reference
core and location reference extension) together constitute a linear set, i.e. they form a list where each
point in the list except the last one relates to the next point in the list, and to no other points. Each point
can have one or more attributes.
On reception of this location reference, the receiving system needs to reconstruct the location as intended
by the sending system. The encoding rules provided in Clause 8 provide the necessary semantics both for
creating the location code at the sending system and for interpreting this code in the receiving system.
Thus, the role of the encoding rules is both to provide constraints for selecting and creating this set of
information elements at the sending system and to provide a consistent interpretation basis for the
receiving system to reconstruct the location reference as intended by the sending system.
This clause describes the building blocks for the dynamic location reference and specifies different types
of attributes. Clause 8 defines the Dynamic Profile LRM as a set of rules. These rules are mandatory, and
any shall adhere to these. Clause 9 defines the minimum requirements for any physical data format,
which is for storing Dynamic Profile Location References of this LRM. Annex D describes hints to add
optional attributes to the dynamic location reference and proposes a coding procedure, which can
serve as a basis for the creation of a coding algorithm. Through application of the rules and the coding
procedure, the sending system should be able to create a location reference that can be interpreted
consistently by a variety of receiving systems if the physical format is well-known. For this reason two
physical formats (binary and XML) are defined in Annexes B and C, based on the logical format in Annex
A. This presents the opportunity to have at least one exchange format usable for the variety of LRS. If
application of an LRM cannot implement either physical format of Annex B or Annex C, the LRS might
specify its own proprietary physical format, still fulfilling all format requirements defined by Clause 9
of this International Standard. A third physical format defined in Annex E is specifically optimized for
implicit areas and location references with precise geometry description and allows storing the location
references in a very size efficient way.
Robustness of the codes is acquired by uniqueness. The information elements used and (certain aspects
of) their combination shall be unique for these different parameters are defined as thresholds, e.g.
the certain area around a point by the default distance D . These parameters are specified in
search_area
different rules and the best known values are given in Table 3.
7.2 Location referencing building blocks
7.2.1 General
In 7.2.2 to 7.2.5, the building blocks for dynamic location reference encoding are defined and specified.
These are points and attributes.
7.2.2 Points
The basis of the dynamic location reference is a set (or list) of points, which can be described as follows.
Point in general
A point can reference an intersection or can reference a position on the road network away from
intersections. The set of points in a location reference constitute a next point relationship such that each
point except the last one refers to one and only one other point (its “next point”).
Furthermore, points are distinguished as to which part of the location reference they belong to, the
location reference core or the location reference extension.
Core Point (CP)
Point belonging to the location reference core, which consists of a combination of three types of core
points: location points, intersection points, and routing points.
a) Location Point (LP)
A core point that represents the start, an intermediate, or the end point of the real-world location
to be referenced.
b) Intersection Point (IP)
A core point representing an intersection, located at places where the road section signature at the
location changes.
c) Routing Point (RP)
A core point used to reconstruct the location by route calculation.
Each core point in the set of points in the location reference core shall represent at least one of the three
core point types defined in this part of ISO 17572.
Extension Point (EP)
Point belonging to the location reference extension. All points in the set of points in the location reference
extension are, by definition, extension points.
7.2.3 Attributes
7.2.3.1 General
Table 1 lists the defined attribute types for dynamic location references and their possible values. Note
that some attributes relate to points and other attributes, to stretches of road network between points
(possibly the whole length of the referenced location). An attribute that describes a characteristic of
a linear stretch is linked in the location code to the point that is at the start point of the stretch. The
following subclauses define some attributes in detail.
7.2.3.2 Functional Road Class
GDF defines this attribute with the purpose of “a classification based on the importance of the role that
the road section or ferry connection performs in the connectivity of the total road network.” It is an
[5]
enumerated list of 10 different values as follows:
— main roads: the most important roads in a given network;
— first class roads;
— second class roads;
— third class roads;
— fourth class roads;
— fifth class roads;
— sixth class roads;
— seventh class roads;
8 © ISO 2015 – All rights reserved

— eighth class roads;
— ninth class roads: the least important roads in a given network.
NOTE 1 Dynamic location referencing uses this classification for distinguishing the parts of the road network,
having a certain higher probability of existence in different databases. A standard map database will deliver this
attribute as defined in GDF; however, the attribute is quite differently used between countries and providers. The
location referencing method considers this in the rules by leaning only on categorizations with high congruence
between different map databases.
NOTE 2 The attribute FC cannot be stored in some databases, but the encoder and decoder need to be able to
derive it from other information available (speed, lanes, routing tables, etc.). For this purpose, Table D.1 provides
an interpretation of the most-used functional road classes in Clause 8.
7.2.3.3 Bearing at a point
The bearing at a given point along a location is the angle between the geographic north and the straight-line
connection from the given point to the intersection of the location with a measuring circle in the location
direction (Pm), as depicted in Figure 1. The radius of the measuring circle is defined with the attribute
“Distance for Measure of Bearing” (DMB), and if it is not provided, with the (parameter) D .
m-bearing
NOTE 1 See Table 3 for values of defined parameters.
The bearing is measured in clockwise direction. The measuring distance of at least attribute DMB, or
respectively, (parameter) D , ensures robustness for observed interpretation differences.
m-bearing
NOTE 2 Road segments of less than 10 m length do not provide sufficient real-world semantics. Frequently,
differences occur between maps of different map vendors due to interpretation differences allowed by GDF.
Once a point along a location has a bearing assigned, then there is a natural way of associating one and
only one road segment with the point. The road segment associated with the point except for the last
point is the road segment leading away from the point in the location direction of the point’s bearing.
Therefore, if the point is not a junction, then the associated road segment is simply the road segment on
which the point is located. If the point represents a junction, then the associated road segment is one
of the road segments incident at this junction and leading away from it in the direction of the point’s
bearing (see Figure 1).
north
D
m-bearing
location
Pm 1
location
direction
point of
location
bearing at a point
reference
Figure 1 — Bearing at a point (general case)
In a case where a point is the last point of the location, the bearing is the angle from the intersection of
the circle and the location reverse to the location direction (see Figure 2).
10 © ISO 2015 – All rights reserved

north
location
end point
of location
location
reference
direction
Pm 2
D
bearing at a end point m-bearing
Figure 2 — Bearing at a point (special case for last point)
7.2.3.4 Connection angle
In a case where, in addition to the bearing, a side road bearing is calculated, the attribute stored is the
connection angle. The connection angle is the difference of the side road bearing (Ps) and the bearing
at a point (Pm) (see Figure 3). Because, especially in intersections, differences in maps are potentially
bigger, the connection angle is calculated with a higher measuring distance DCA than for the bearing. The
attribute “Distance for measuring of Connection-Angle” (DCA), respectively (parameter) D ,
m-co-angle
ensures robustness for observed interpretation differences at intersections.
NOTE 1 See Table 3 for values of defined parameters.
NOTE 2 Road segments of less than a given length do not provide sufficient real-world semantics. Frequently,
differences occur between maps of different map vendors due to interpretation differences allowed by GDF.
7.2.3.5 Location direction
A location reference has an implicit direction, which is defined by the order of the points in the set of
points that constitute the location reference core. The positive direction or from-to direction is from the
first point in the set to the last point in the set. Note that this direction shall coincide with the direction
to be referenced, if only one direction is referenced.
The attribute Location Direction (LD) has the following values:
— aligned The location has one direction, corresponding to the implicit direction defined by the
order of the points.
— both The location has two directions, both in the implicit direction and in the reverse
direction.
north
side road
Ps location
Connection angle
Pm
location
direction
point of
location
D
m-co-angle
reference
Figure 3 — Connection angle at a point
7.2.3.6 Location type
A location reference defines the type of the object to be referenced. The decoder will use this information
to optimize its effort of decoding the location by a first presumption what type of object it is supposed to
search for in its database. For this reason, the following values are defined (based on GDF and adapted
for this context) with given purpose:
— Intersection The location is part of an intersection.
— Restricted access road The location is part of a road that is subject to restricted access for cer-
tain categories of road users (e.g. pedestrian zone).
— Ferry The location is part of a ferry connection.
— Settlement The location is part of a settlement (i.e. area with a residential, recrea-
tional, industrial, or military character).
— Point-of-interest The location is a point of interest (e.g. a specific route destination for a
service).
— Road The location is a part of a road, without specific character, including
motorways or other types of limited access roads.
12 © ISO 2015 – All rights reserved

7.2.3.7 Driving direction at a point
The driving direction (DD) at a point (along the location) expresses the legally permissible driving
direction under normal conditions for passenger cars at the point relative to the bearing at the point.
Stated in terms of the rule above, it expresses the driving direction of the road segment leading away
from the point along the path in terms of the point’s bearing. Alternatively, using the definition of the
bearing of a point along a path of non-zero length, it can be determined as follows.
If the point is not the end point of the path, then the driving direction pertains, in terms of the most
detailed level geometry, to the driving directions of the road segment pointing away from the point in
location direction.
If the point is the end point of the path, then the driving direction pertains, in terms of the most detailed level
geometry, to the driving directions of the road segment pointing towards the point in location direction.
NOTE In GDF 4.0 terminology, the attribute “Direction of Traffic Flow” for vehicle-type passenger cars. In a
revision of the GDF standard (GDF5.0), this attribute is replaced by the attribute “Conditional Traffic Flow”, which
specifies direction of traffic flow per direction separately.
The driving direction can have the following values:
— none Driving is not allowed on the road segment.
— aligned The only allowed driving direction coincides with the bearing.
— reverse The only allowed driving direction is opposite to the bearing.
— both Both driving directions are allowed on the road segment.
— undefined Driving direction information is not available in the database.
7.2.3.8 Accessible for routing flag
The accessible for routing (AFR) flag at a point represents information for routing on road segments
connected to a point. The flag is set to 0 (false) if the segment following the point is not access
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