CSIS Discussion Paper No.148

Use cases and basic concept proposal for Lane Level Location Referencing
Satoru NAKAJO**Center for Spatial Information Science, the University of Tokyo, Japan
Cw503 4-6-1 Komaba Meguro-ku Tokyo Japan 153-8505
Tel: +81-3-5252-6412 snakajo@csis.u-tokyo.ac.jp

Abstract
The needs for precise location information exchange is increasing such as for automated driving
and for safety application in ITS. Location information exchange in lane level is required broadly. In thispaper, basic concept of a lane level location referencing method is briefly explained. The main concept
explained on this paper is come mainly from the result of discussion between the authors. The purpose of thispaper is to make a reference for further research and creating a standard within the global level.

KEYWORDS:
Location Referencing, Spatial Information Distribution/Exchange, Automated Driving, Dynamic
Map

1. Introduction
The needs for location referencing method which can use in lane level is increasing because of therapid technological progress in autonomous driving and cooperative systems in ITS. On the other hand, there
are no widely used standard which can execute location referencing within lane level. Based on the situation
above, the authors have decided to create a location referencing method which can use for autonomous driving
and cooperative systems within lane level.
In this paper, Use cases in service level and function level and constituents of Location
Referencing Method are briefly described. The authors noticed that some of the ideas described in this paper
may need further research for realizing an actual use.

2. Use cases
12.1 Service level
We defined several use cases for service levels as follows based on several discussion with related
professionals in Japan and overseas. We noticed that there two types of services. One is the use cases to deliver
the location as “which lane” and the other is as “where in a lane”. We defined use cases for both types.

<Use cases for “which lane” information delivering>1) Exchange the lane information of the vehicle2) Delivering road changes or obstacles

23) Delivering lane closure at toll gates4) Delivering lane closure at road sections35) Delivering signal timing information<Use case for “where in a lane” information delivering>42.2 Function level
We defined several use cases for function level as follows. In function level, we defined type ofroad and defined the shape of road, road link, lane link and needed delivering messages. We defined the roadlink and lane link just for a reference for discussing the necessary location information. We do not intend to
standardize the road link or lane link model in this paper.

Type1) Ordinary road

Shape of road
70%(560m)

Road link

100%(800m)
lane link
：CRP
：node
：Contents：Road linknode：lane linknode

：CRP
：node
：Contents：Road linknode：lane linknode

70%(560m)

Road link

100%(800m)
lane link
Common Information
Version (100)Content (Falling Object)
Content ID (1)Content type (1)Area frag (2)Method of location referencing (2)Number of point (1)
1..n

1..n

Distance from the CRP level2

Delivering data※

Distance between CRP level 2s
and Offset

CRP level 2 ID
Δx
Δy
Δz

Start CRP level 2 ID (0001)
Stop CRP level 2 ID (0002)
Percentage along distance fromStart CRP level 2 (70)
Number of the lane (1)Mandatory items

1..n
Lane

Content type

Lane number (1)Direction of the lane (1)Percentage along distance of thelane crossing direction (30)

Point
Line
Polygon5

Type 2) Junctions●●IC▲▲ジャンクション●●ジャンクション

Shape of road

90%(4,500m)

Road link

100%(5,000m)
lane link

：CRP
：node
：Contents：Road linknode：lane linknode

：CRP
：node
：Contents：Road linknode：lane linknode

90%(4,500m)

Road link

100%(5,000m)
lane link
Common Information
Version (100)Content (Falling Object)
Content ID (1)Content type (1)Area frag (2)Method of location referencing (2)Number of point (1)1..nDistance from the CRP level2
CRP level 2 ID
Δx
Δy
Δz

Delivering data※

1..nDistance between CRP level 2s
and Offset
Start CRP level 2 ID (0001)
Stop CRP level 2 ID (0002)
Percentage along distance fromStart CRP level 2 (90)
Number of the lane (3)1..nMandatory items

Content type
Point
Line
PolygonLane
Lane number (2)Direction of the lane (1)Percentage along distance of thelane crossing direction (30)6Type 3) Small intersections

Shape of road60%(480m)

Road link

100%(800m)

lane link
：CRP
：node
：Contents：Road linknode：lane linknode60%(480m)

Road link
100%(800m)*

lane link
Common Information

：CRP
：node
：Contents

Version (100)Content (Falling Object)
Content ID (1)Content type (1)Area frag (2)Method of location referencing (2)Number of point (2)Delivering data※

Mandatory items

1..n

1..n

Distance from the CRP level2

Distance between CRP level 2s
and Offset

CRP level 2 ID
Δx
Δy
Δz

Start CRP level 2 ID (0001)
Stop CRP level 2 ID (0002)
Percentage along distance fromStart CRP level 2 (60)
Number of the lane (2)
1..n
Lane

Content type

Lane number (1)Direction of the lane (1)Percentage along distance of thelane crossing direction (10)

Point
Line
Polygon

7：Road linknode：lane linknode

Type 4) Inside in a lane

Δy=6m

Shape of road

Δx＝5m

：CRP
：Contents

Common Information
Version (100)Content (Falling Object)
Content ID (1)Content type (1)Area frag (1)Method of location referencing (1)Number of point (1)Delivering data※

Mandatory items

1..n

1..n

Distance from the CRP level2

Distance between CRP level 2s
and Offset

CRP level 2 ID (0001)
Δx （5）Δy （6）Δz （0）Start CRP level 2 ID
Stop CRP level 2 ID
Percentage along distance fromStart CRP level 2
Number of the lane
1..n
Lane

Content type

Lane number
Direction of the lane
Percentage along distance of thelane crossing direction

Point
Line
PolygonType 5) In an intersection

Shape of roadΔy=-4mΔx＝50m：CRP：Contents

Common Information
Version (100)Content (Falling Object)
Content ID (1)Content type (1)Area frag (1)Method of location referencing (1)Number of point (1)Delivering data※

Mandatory items

1..n

1..n
Distance from the CRP level2

Distance between CRP level 2s
and Offset

CRP level 2 ID (0001)
Δx （50）Δy （-4）Δz （0）Start CRP level 2 ID
Stop CRP level 2 ID
Percentage along distance fromStart CRP level 2
Number of the lane
1..n
Lane

Content type

Lane number
Direction of the lane
Percentage along distance of thelane crossing direction

Point
Line
Polygon8

Type 6) Toll gate

98%(1,960m)
Road link
100%(2,000m)*
ETC

lane link
ETC

：CRP
：node
：Closed lane

：Road linknode：lane linknode98%(1,960m)
Road link
100%(2,000m)*

ETC

lane link
ETC

Common Information

：CRP
：node
：Closed lane

Version (100)Content (Closedown of the tollgate)
Content ID (1)Content type (1)Area frag (5)Method of location referencing (2)Number of point (1)Delivering data
※

1..n

1..n

Distance from the CRP level2

Distance between CRP level 2s
and Offset

CRP level 2 ID

Mandatory items ΔxΔyStart CRP level 2 ID (0001)
Stop CRP level 2 ID (0002)
Percentage along distance fromStart CRP level 2 (60)
Number of the lane (5)

Δz

1..n
Lane

Content type

Lane number (1)Direction of the lane
Percentage along distance of thelane crossing direction

Point
Line
Polygon

9：Road linknode：lane linknode

Type 7) Accident around a tall gate

ETC

Δy＝30mETC

Δx＝-50m

lane link

ETC

ETC

：CRP
：node
：Contents

ETC

lane link
Δy＝30mETC

Δx＝-50m

Common Information
Version (100)Content (Traffic accident)
Content ID (1)Content type (1)Area frag (1)Method of location referencing (1)Number of point (1)Delivering data※

Mandatory items

1..n

1..n

Distance from the CRP level2

Distance between CRP level 2s
and Offset

CRP level 2 ID (0001)
Δx （-50）Δy （30）Δz （0）Start CRP level 2 ID
Stop CRP level 2 ID
Percentage along distance fromStart CRP level 2
Number of the lane
1..n
Lane

Content type

Lane number
Direction of the lane
Percentage along distance of thelane crossing direction

Point
Line
Polygon10

3. Requirements for a lane-level location referencing system
General requirements for a location referencing had already defined in ISO17572 Part1. On thispaper, the authors had tried to define additional requirements for a lane-level location referencing system.
There are four additional requirements are defined.

R-1. A Lane-level location reference will have an accuracy with location measurement errors ofσ<25cm. It is likely that maps will be used in conjunction with in-vehicle sensor information. That being thecase, the map and the in-vehicle sensor must have equivalent locational accuracy. For instance, if the vehicle
needs to detect an object of 1 meter in width, the effective detection distance will be 200 meters with current
in-vehicle sensor technology and the required relative accuracy at the distance of 200 meters will be ±1m.
Depending on the map, accuracies with location measurement errors of σ<25cm will be required for the invehicle sensor to be accurate as the map. This is because 4σ falls within a measurement error of roughly 1
meter. .
R-2. A Lane-level location reference will take into account the situation that some of the senders/receivers may not have lane information. When the sender and the receiver are different entities, they may use
different provider maps. In such a case, because the accuracy of the maps may differ, it will become necessary
to determine a common location referencing rule.
R-3. A lane-level location reference will express location reference under 3-dimensional
circumstances taking into account traverse banking. Location referencing on the map will be possible evenwhen banking exist.
R-4. A lane-level location reference will take into account that coordinate values may be off-pointdue to change over the years. For instance, it has a(n) (Earth’s) crustal movement of 20 cm/year in some point
in Japan, so there may be discrepancies between the true location determined in real-time with a high-accuracy
GPS and the location on a map created in the past.

4. General Concept of the system
This method is being adopted for lane-level location references, a level that allows for locationreferencing within lanes. Location referencing via this method will assume the use of CRP (Common
Reference Point). A CRP is a virtual point that is able to be referenced by the relative locations with regard to
real-world geographic objects. CRP contains locational information and ID. When using this method forlocation referencing, the following condition will apply: The locational information and ID of the CRP will beshared by the sender and receiver of the locational information in advance.
When locational information would like to be sent for an event, the sender will send the receiver

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the nearby CRP ID and the relative locational information from the CRP. By doing so, the sender and receiverwill be able to reference the event location on their mutual maps even if they have different maps. (See Figure1)

Location
Reference
sendingmessage

DigitalMap
displaying

Sender’s map

Display

Receiver’s map
modeling

modeling

Event

Actualworld

CRP

Figure 1 Concept of location referencing using CRP
There are two (2) ways to reference location that use this method (method 1 and 2 described below). Method 1
will be used in locations that require accuracies with location measurement errors of σ<25cm, while method 2
will be used for all other locations.
(Method 1) Delta from the CRP(Method 2) Distance between CRPs and Offset(Method 1) Delta from the CRP
The location will be referenced by using the incremental distance from CRP (Δx, Δy, Δh).
In order to achieve an accuracy with location measurement errors of σ<25cm when using this method, thefollowing condition will apply:
The location will be referenced by using the incremental distance from CRP (Δx, Δy, Δh).
(Method 2) Distance between CRPs and Offset
The location will be referenced by using distance between CRPs (the distance from the starting
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CRP within the distance between the CRPs) and offset.
As a general rule, the distance between CRPs will be measured along the centre line of the route.
Furthermore, the travel distance representation will not be uniquely defined.

Delta from the CRP△x, △y, △h CRP01
from CRP01

CRP02
Distance between CRPs and Offset

Figure 2 Explanation of lane level location referencing

5. Definition proposal of CRP
CRP is defined to be a virtual point that is referenced using the relative distances from real
geographic objects. It contains locational information and ID. AP(Anchorage Point) is a geographic point that
represents the geographic objects which exists on the road that is defined on both the sender and receiver’s
maps. The geographic objects to which they belong have the following characteristics:-

Actual objects/features that rarely change.

-

Objects/features that are detectable from vehicles using sensors (lasers, cameras, etc.) under ideal
circumstances.

(An) AP(s) is/are used to construct CRP(s) on maps which will become the basis for referencing
locational information. CRP will be the basis for referencing the locational information of events in which
determining high accuracy location is desirable. CRP will be shown by the relative distance(s) from AP(s).
Furthermore, it is desirable to have the CRP constructed from at least two (2) APs given the possibility ofsituations such as the following:-

A geographic object that is to be an AP is destroyed by phenomena such as accidents.

-

The AP may not be able to be detected from the vehicle from certain directions.
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Figure 3 indicates the relationship between AP and CRP and the elements they contain.
Furthermore, the latitude, longitude, and height of the CRP is a definite location and will be used as reference
values in determining most locations on a map.

CRP
+ CRP ID
+ Anchoring AP ID+ Delta from AP (x, y, h)+ Latitude for reference+ Longitude for reference+ Height for reference
1..*

1..*
AP
+ Kind/Name of the feature+ AP ID+ Belonging CRP ID+ Latitude+ Longitude+ Height

Figure 3 Data structure proposal of CRP

5 Specification proposal for contents delivering message
The data structure of lane-level location references is shown in Figure 4. There are two (2) ways toreference location that use this method (method 1 and 2 described below). Method 1 will be used for locations
that require accuracies with location measurement errors of σ<25cm, while method 2 will be used for all otherlocations. Both location referencing methods contain point, linear, and polygon information.

(Method 1) Delta from the CRP
The sender of the locational information will send the CRP ID(s) necessary for locationreferencing and the incremental distance from the appropriate CRP(s).
In defining the incremental distance, the CRP will be defined as the origin, the positive Y-axis will extend
14northward from the CRP, the positive X-axis will extend perpendicular to the Y-axis to form the coordinate
plane, and Δx and Δy will be measured from the origin. Positive Δh will be defined as the direction oppositethat of gravity with the road surface as the origin. All incremental distances will be measured in meters.
The receiver of the location information will determine the location of the event from the incremental distancefrom the appropriate CRP(s) on its own map by referencing the CRP ID(s) received.

(Method 2) Distance between CRPs and Offset
The sender of the locational information will send the Start CRP ID, Stop CRP ID, Percentage
along distance from start CRP, Offset direction, and Offset distance meter, and Direction of the road.
Furthermore, the transfer of Position on the road and Number of the lane will be optional. This is because astandardized definition of these elements is difficult to establish due to differences in each country’s roadstructure.
The determination of Start CRP and Stop CRP will use Direction of the road. The two (2) points
nearest in the forward and backward direction of Direction of the road from the location referencing point will
be Start CRP and Stop CRP. Of the two (2) CRPs, the point closer to the location referencing point will beStart CRP.
Furthermore, the forward and backward direction of Direction of the road will not be dependent
on the directions used in highway operation.
The receiver will determine the location of the event sent from the information received, Start
CRP ID, Stop CRP ID, Percentage along distance from start CRP, Offset direction, and Offset distance inmeter. In cases that involve multi-lane roads, Number of the lane is used to determine in which lane the event
is located.

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Lane level
ProfileBasic Description+ Location referencing
express patterns+ Content Type

0..1
Delta from the CRP

0..1
Distance between CRPs
and Offset+ CRP ID

0..n

1..n

Delta

Along Distance

+ Δx
+ Δy
+ Δh

+ Start CRP ID+ Stop CRP ID+ Percentage along
distance from start CRP+ Offset direction+ Offset distance in meter+ Position on the road
+ Direction of the road
+ Number of the lane

Content Type+ Point+ Linear+ Polygon

Figure 5 Contents delivering message data structure proposal

6. Conclusion
In this paper, the authors briefly discuss the basic concept of lane level location referencing
method. To realize and to be widely used in the world, it will be necessary to enhance the discussion between

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various kinds of experts related to location information and autonomous driving. It will be needed tostandardize this method officially internationally is also needed.
To make this method useful, at least two challenges of the following should be conquered.
First is the definition for distinguish the lanes. At this moment, the proposed data structure
contains the element of lanes but the details are not defined yet. This part should be clearly defined.
Second is the definition for deploying for CRPs and APs. In this paper, the concepts of CRP and
AP are described but how to deploy to the real world is sitill remaining as a challenge. A rule should be defined
under real world field test.

References
1) ISO 17572-1:2015, Intelligent transport systems (ITS) -- Location referencing for geographic databases -Part 1: General requirements and conceptual model, 2015
2) ISO 17572-2:2015 Intelligent transport systems (ITS) -- Location referencing for geographic databases -Part 2: Pre-coded location references, 2015
3) ISO17572-3:2015 Intelligent transport systems (ITS) -- Location referencing for geographic databases -Part 3: Dynamic location references, 2015
4) ISO 19148:2012 Geographic information -- Linear referencing, 20125) Satoru NAKAJO, -Personal Perspective- Location Referencing for lane level information,
ISO/TC204/WG3 meeting, 13 October 2015 (Personal Access)6) Satoru NAKAJO, Ryosuke SHIBASAKI, Realizing for Lane Level Location Referencing, 13th ITS
Symposium in Japan, 3 December 2015 (Japanese)
7) Ryuichi IMAI, Satoru NAKAJO, Mitsuaki MATSUYAMA, Koichi SHIGETAKA, Minoru ISHIDA and
Takahiko HAMADA, Location Referencing Method for Distribution for Various Road Related Data, April.
2012, Journal of Japan Society of Civil Engineers. (Japanese)
8) Kees WEVERS, Transport Network ITS Spatial Data Deployment Platform Purpose, status and prospects,
Joint UNECE-Belgium Workshop on ITS, 18 November 201417