ISO 10711:2012

INTERNATIONAL ISO
STANDARD 10711
First edition
2012-01-15

Intelligent Transport Systems — Interface
Protocol and Message Set Definition
between Traffic Signal Controllers and
Detectors
Systèmes intelligents de transport — Protocole d'interface et définition
des ensembles de messages entre régulateurs de signaux de
circulation et détecteurs




Reference number
ISO 10711:2012(E)
©
ISO 2012

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ISO 10711:2012(E)

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©  ISO 2012
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ISO 10711:2012(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 2
3  Terms and definitions . 2
4  Abbreviated terms . 2
5  Interface protocol for traffic controller . 3
5.1  Relationship to other standards . 3
5.2  Identification detector index . 3
5.3  Detector classification . 4
6  Interface messages for traffic signal controller . 5
6.1  General frame structure . 5
6.2  Detector information messages structure . 7
Annex A (normative) Interface Protocol Message Set Definition between Traffic Signal Controllers
and Detectors data structure and data type definition . 16
Annex B (informative) Interface Protocol and Message Set Definition between Traffic Signal
Controllers and Detectors implementation example . 23
Bibliography . 25

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ISO 10711:2012(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 10711 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.

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ISO 10711:2012(E)
Introduction
Real-time traffic signal control systems use traffic detectors to obtain traffic flow information. Each detector
has its own method for collecting traffic information. Most popular is the loop detector which reports traffic data
through detection of vehicle occupancy. Each method supporting different forms of detection has its own
merits and disadvantages and uses a variety of message sets and protocols for communication which
complicates their integration into systems.
There are two methods for integrating different types of traffic detectors. One method is to select and/or
analyse the necessary information from detectors using their own message sets. The second method is to
standardize the message sets and protocols to be used for the interface between detectors and traffic signal
controllers. The former has the disadvantage that the signal controller must be customized each time a new
detector type is introduced. The latter approach has the advantage of supporting consistent collection of traffic
data without consideration of detectors' detection principles and characteristics. Thus, the second method has
advantages when the use of the data is known.
This International Standard defines detector message sets applicable to traffic signal control. There are three
different message sets according to the detection method: occupancy based; image processing based; and
vehicle identification based. All detectors should be assigned to one of these three categories. The message
sets do not contain hardware information and additional information that is not critical to the traffic signal
control.
Regardless of their physical functions or manufacturing methods, all current traffic detectors can use one of
the three types of message sets for communicating with traffic controllers. Using this International Standard,
there is no need to include specific manufacturer's technical codes as a part of the data exchange.
This International Standard allows the signal controller to query and change the detector settings for the
commonly applicable contents such as attributes identifying the installed location of the detector. For image
processing based detectors, this International Standard includes minimal well-known generic camera control
commands.
[2]
The encoding rules and lower layers of the OSI communications stack (e.g. transport) are left to national
standards.
The benefits are
a) all detectors can adopt one of the three types of predefined message sets, thus configuration of traffic
detector system for traffic signal control becomes more simple regardless of hardware properties and
manufacturing method,
b) it is not necessary to replace or revise traffic signal controller software when a new type of detector is
installed and a new detector adopting one of the three message sets will not have communications
interoperability problems, as all of the necessary information items for signal control have been
considered, and
c) minimizing the communications load achieved with the compact size of predefined information; this
advantage can be applicable to short range wireless communication with its weakness in the multi-
channel simultaneous communication owing to hand-shaking and frequency interference.
Annex B provides an informative example of how the interface protocol and message sets are implemented.

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INTERNATIONAL STANDARD ISO 10711:2012(E)

Intelligent Transport Systems — Interface Protocol and
Message Set Definition between Traffic Signal Controllers and
Detectors
1 Scope
This International Standard defines protocols and message sets between traffic detectors and traffic signal
controllers. It is applicable to the various types of traffic detector technologies currently in use for real-time
traffic signal controls. The scope of this International Standard is limited to parameter generation to be used
for traffic signal control and for the interface between traffic signal controllers and detectors.
This International Standard defines message sets that contain data collection and control protocol for three
different types of detectors of traffic signal control systems:
 detectors that deal with occupancy information;
 detectors that deal with image information;
 detectors that deal with vehicle identification.
The scope of this International Standard does not include the following cases:
 interfaces between sensors [including tag or on-board units (OBU)] and detector controllers;
 interfaces between traffic signal controllers and centres;
 when signal controllers only relay data from field-side detectors to central computers;
 when signal controllers receive unencoded electrical signals from cable-connected detectors and not
data from detectors.
Physical scope is limited to the communication interface between traffic signal controllers and traffic detectors.
The scope does not include the interface between the traffic detector and its own controller.
Tag or OBU
Traffic
controller
assembly
Image
Detector
Controller
Loop

Figure 1 — Physical scope
This International Standard is limited to the definition of the message sets used to exchange detector
information relevant for traffic control and the logical rules governing the exchange of these messages.
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ISO 10711:2012(E)
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 15784-3:2008, Intelligent transport systems (ITS) — Data exchange involving roadside modules
communication — Part 3: Application profile-data exchange (AP-DATEX)
ISO 14827-2:2005, Transport information and control systems — Data interfaces between centres for
transport information and control systems — Part 2: DATEX-ASN
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15784-3 and the following apply.
3.1
occupancy based detector
detector that detects vehicles and traffic characteristics based on the state of the occupancy using methods
such as loop or magnetic detectors
3.2
image processing based detector
detector that detects vehicles based on the real-time image data from the digital camera which has virtual
sensing lines for estimating queue length or other parameters in approaching lanes
3.3
vehicle identification based detector
detector that detects vehicle identities based on wireless communication with tags or on-board units (OBU) in
the vehicle, which transmits the vehicle's identity information to the traffic signal controller
3.4
detection zone
area on the road surface where the target or the group of targets actuates the detector
NOTE Adapted from DS/ENV 13563.
3.5
detector information type
information type that designates the type of information from linked detectors which can be occupancy based,
image processing based or vehicle identification based
3.6
direction discrimination
direction of travel of a target within the detection zone
NOTE Adapted from DS/ENV 13563.
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
ID Identifier
IPMSTSCD Interface Protocol and Message Set Definition between Traffic Signal Controllers and Detectors
MIB Management Information Base
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ISO 10711:2012(E)
OBU On-Board Unit
OSI Open System Interconnection
PDU Protocol Data Unit
RSE Roadside Equipment
5 4BInterface protocol for traffic controller
5.1 6BRelationship to other standards
For the interface, this International Standard defines for each application the scope of the
1) framework in the protocol stack,
2) object encoding rules, and
3) transportation management protocol.
The interface defined within this International Standard secures interoperability by adopting the lower layer of
the protocol stack and specified standards for encoding rules, transport management rules and data
structures. The criteria for detector controller and traffic signal controller define the designating method for the
detectors.
The information should be exchanged according to the protocol profile defined in ISO 15784-3 and
ISO 14827-2.
5.2 7BIdentification detector index
5.2.1 11BIdentification method
A traffic signal controller collects data from each connected detector controller using the message sets defined
in this International Standard. Each detector controller reports information about its detectors, with each
detector identified by a unique sequential identifier. However, since the traffic signal controller may be
connected to multiple detector controllers, the traffic signal controller shall, where required, support a cross-
reference table that translates the local detector identifier into an identifier that is unique for the entire scope of
the traffic signal operation, as shown in Figure 2.
ID Type
1
5
1
Taffic
Image Type
6
2 Signal
Controller
detector detector logical detector
index numbers
controller index numbers
wireless
of detector controller index numbers of signal controller
device
Loop
Type
1
7
Loop
Type
2
8
2
Loop
Type
3
9
detector index
cross reference table

Figure 2 — Detector identification concept (example)
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ISO 10711:2012(E)
If and when the traffic signal controller transmits detector data to a higher level system (outside of the scope of
this International Standard), it should use the derived detector ID that is unique within the full scope of the
traffic signal operation.
5.2.2 12BRequest and response
The protocol of this International Standard supports event-driven, request-response and periodic data
exchange methods.
5.3 8BDetector classification
5.3.1 13BManaging multi-detector environments
The protocol supports the ability for a traffic signal controller to communicate with multiple detector controllers.
In such a model, the traffic signal controller does not receive a constant analogue stream, but rather receives
packets of data that managed on a cyclical basis.
5.3.2 14BOccupancy based detector
An occupancy based detector controller is able to report occupancy rate and vehicle speed to the traffic signal
control system by determining the percent of time the sensor is detecting a vehicle. The information is used for
calculating signal phases. However, if an occupancy based detector on the roadway has its own digital
communication capability, then it can be regarded as a detector controller. These detector controllers are then
linked sequentially with the traffic signal controller.
Any sensor that can detect vehicle presence can be used as an occupancy based detector. For example:
Loop Square, Loop Rectangle, Loop Circle, Magnetic, Ultrasonic, Laser, Infra-red, Microwave.
magnetic sensor with
wireless transmitter
magnetic sensor
Connection
in a sequence

Figure 3 — Occupancy based detection concept
5.3.3 15BImage processing based detector
An image processing based detector controller collects camera images and reports detection information with
respect to a virtual polygon detection zone in each lane. An image processing based controller has its own
physical detector index, which is the same as the lane ID assigned from the median with descending (or
ascending) order which is dependent upon each country's practice. Any lane without detection also has its
own ID but with no information supplied.
The image processing based detector controller collects real-time camera images, detects the traffic volume
with the change of images in the virtual detection zone and optionally transmits the queue length information
by edge detection to traffic signal control system.
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ISO 10711:2012(E)
image detection
zone

Figure 4 — Image processing based detection concept
5.3.4 16BVehicle identification based detector
A vehicle identification based detector controller reports identification (ID) information for individual vehicles,
identifies various vehicle properties and transmits the information to the traffic signal controller.
The vehicle identification based detector controller provides real-time vehicle ID information such as barcode,
license plate, electronic tag, etc. This information can then be used by a corridor-based or area-based system
to determine the real-time situation of the traffic network.
Read vehicle
information from
RSE
OBU or tag
Identify vehicle
Vehicle
from barcode
identification
information
Identify vehicle
OBU
from license plate
Identify vehicle from its
Colour, Layout etc
physical Characteristics

Figure 5 — Vehicle identification based detection concept
6 5BInterface messages for traffic signal controller
6.1 9BGeneral frame structure
Messages defined in this International Standard use a structure that consists of a detector controller's
information followed by information for each detector connected to that detector controller. This is depicted in
Table 1. However, it is noted that interfaces defined to standards such as ISO 15784-3 do not use this
structure.
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ISO 10711:2012(E)
Table 1 — Detector controller's information and IPMSTSCD_Data field
Detector controller's information IPMSTSCD_Data
(Optional) (Optional)
Detector controller's Detector controller's
index number time-location
Detector information Detector information
…
#1 #n
(Mandatory) (Optional)

Physical detector index Information Detection Detector's
of detector controller type information time-location
(Mandatory) (Mandatory) (Mandatory) (Optional)

6.1.1 Detector controller's information
Detector controller's information consists of two data elements: the detector controller's index number; and the
detector controller's time-location. When each detector controller reports information collected from its
detectors, the detector controller's information is concurrently transmitted to the traffic signal controller to
identify from which controller the detector information comes.
6.1.1.1 Detector controller's index number
Detector controller's index number is the unique identification number of each detector controller (or a
roadside device) connected with its sensors. As shown in Figure 2, a traffic signal controller may be
connected to multiple detector controllers and, thus, in this case a unique index number is required.
6.1.1.2 Detector controller's time-location
Detector controller's time-location is a data structure supporting representation of time and location
information of each detector controller (or a roadside device) as defined in ISO 14827-2. Location information
is the spatial position of each detector controller. If included, the location information shall be expressed in
terms of the longitude, latitude and elevation where each detector controller has been installed. Time
information is the detector controller's response time when collected data is transmitted to the traffic signal
controller. The data structure for the detector controller's time-location is shown in Table 2. Detector
controller's time-location and detector's time-location use the time-location data structure object named
GeneralTimeLocationCore.
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ISO 10711:2012(E)
Table 2 — Time-location data structure object (GeneralTimeLocationCore)
Item Name Description Reference Need Format
otdv_CurrentTime Response time of ISO 14827-2 Mandatory Time Object
detector controller or
data acquisition time
of each detector
otdv_LocationLongitude Detector controller's New Optional INTEGER
or detector's
longitude (-180000000.180000000)
otdv_LocationLatitude Detector controller's New Optional
or detector's latitude
otdv_LocationElevation Detector controller's New Optional INTEGER(-8192.57344)
or detector's altitude (Optional)
6.1.2 IPMSTSCD_Data
The information from a number of sensors or detectors is organized in a row oriented structure, with
information from each detector containing physical detector index, information type, detection information, and
detector's time-location.
6.1.2.1 Physical detector index
Detector index shall be assigned by each detector controller, as shown in Figure 2.
6.1.2.2 Information type
Information type shall use one of the following types: occupancy based, image processing based or vehicle
identification based.
6.1.2.3 Detection information
The information field contains detector information (5.2). The objects for vendor oriented information collection
are permitted. The object is classified by CHOICE statement.
6.1.2.4 Detector's time-location
Detector's time-location is a data structure representing the time when spot information is collected and the
location where the detector sensor head is located. It uses the same Time-Location data structure as the
detector controller's time-location, as shown in Table 2.
6.2 Detector information messages structure
This subclause defines the message set for information from detector controller to traffic signal controller. The
message sets consist of two types with each kind of detector. One type (Type 1) is used where each detector
has only one message set for sending data to a signal controller. This type is relatively simple and efficient
due to the fixed structure. Another type (Type 2) is used where each detector uses one of several potential
message sets for sending data to a signal controller as the specific application demands. Type 2 is able to
configure the communication to support the specific application. It is noted that type 2 may not have the frame
structure such as defined in 6.1; each item is sent at an appropriate time with barebones set.
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ISO 10711:2012(E)
6.2.1 Occupancy based detection data structure
(1) Type 1
Table 3 shows the list of message sets with type 1 occupancy based detection.
Table 3 — Occupancy based message set
Item Name Description Remark
loopDataDuration Duration for collecting current data (sec) Optional
loopOccupancyState Current state of occupancy (BOOLEAN) (state) Mandatory
loopOccupancyStateDuration Current duration of occupancy (millisecond) (state) Mandatory
Duration of previous state of occupancy
loopOccupancyPreviousStateDuration Mandatory
(millisecond) (state)
loopOccupancyRate Occupancy rate of detection period (%) (cycle) Mandatory
loopSpeed Average speed of detection period (km/h) (cycle) Optional
Traffic volume of detection period (number of vehicles)
loopVolume Mandatory
(cycle)
Detected occupancy/non-occupancy list during detection
loopOccNoccHistory Optional
(cycle)
loopErrorState Malfunction information of occupancy based detector Optional
loopUserData Detector user data Optional
loopTargetType Classification of the Target Optional
loopDirectionDiscrimination Direction of the target (BOOLEAN) Optional
Occupancy state and cycle based statistical information can be utilized according to the communication
properties. State information which minimizes the data polling interval to milliseconds can be utilized. Cycle
based information is utilized as a general communication within which the data polling interval is relatively long.
Occupancy state (loopOccNoccHistory) is defined below. The loopVolume record designates the traffic
volume.
IpmstscdOccNoccHistory ::= SEQUENCE {
OccupancyTimes INTEGER,  -- msec
NonOccupancyTimes INTEGER  -- msec
}
Error information of the detector (LoopErrorState) shown in Table 4 is encoded as follows: open loop
circuit(1); short loop circuit(2); occupancy error(3); non-occupancy error(4); traffic volume error(5); parameter
invalid(6); management (maintenance) required(7).
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ISO 10711:2012(E)
Table 4 — Occupancy based error information
Data element name Description
OpenLoopCircuit Open circuit of loop detector header or feeder (Open)
ShortLoopCircuit Short circuit of detector header or feeder (Short)
OccupancyError Minimum occupancy error (lower than predefined parameter)
NonoccupancyError Minimum non-occupancy error (lower than predefined parameter)
VolumeError Traffic volume error (exceeds predefined saturated traffic flow rate)
ParameterInvalid Parameter out of range
ManagementNeeded Error that needs maintenance
loopTargetType identifies the classification of the targets to be detected on a detector. The target types can be
adequately classified and specified by standards available. For instance, a European standard, DS/ENV13563
may be referred to, in which the target type is classified into four types: pedal cycles, motor cycles, cars and
goods vehicles by target length.
'loopDirectionDiscrimination' is used to discriminate the direction of travel of a target. 'TRUE' is used to
represent the target approaching to an intersection and 'FALSE' is used to represent the target leaving from
an intersection.
(2) Type 2
Table 5 shows the lists of message sets with type 2 occupancy based detection. It is noted that all message
sets in Table 5 do not have to be implemented in detectors.
Table 5 — List of message sets for occupancy based detection
No Message Set Name Remark
1 Accumulative detection Mandatory
2 Time-series of passing vehicles Optional
3 Vehicle speed Optional
4 Specific vehicle detection Optional
5 Detector status Optional
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ISO 10711:2012(E)
Table 6 — Accumulative detection message set
Item Name Description Remark
Det-nbr Detector index number Mandatory
Det-Status Detection status Optional
Accumulation counter of traffic volume. This counter uses from 0 to the
Density Mandatory
designated maximum value cyclically.
Accumulation counter of detection status (on-pulse) by the designated
Occupancy sampling. This counter uses from 0 to the designated maximum value Mandatory
cyclically.
Accumulation counter of error pulses by the designated sampling. This
DetPulseErr Mandatory
counter uses from 0 to the designated maximum value cyclically.

The message set defined in Table 6 is sent in response to a request from a signal controller. Therefore, signal
controller needs to do subtraction of previous data values from the current ones for use in signal control
parameter generation. It is possible to realize flexible communication as the specific application demands as
each signal controller has the ability to set the interval of detector data collection.
Table 7 — Time-series of passing vehicles message set
Item Name Description Remark
Det-nbr Detector index number Mandatory
Det-Status Detection status Optional
Each bit in the octet strings shows passage of vehicles for the
SerialInfo Mandatory
designated seconds.
Table 8 — Vehicle speed message set
Item Name Description Remark
Det-nbr Detector index number Mandatory
VehicleType Vehicle classification Mandatory
Velocity Vehicle speed (km/h) Mandatory
Table 9 — Specific vehicle detection message set
Item Name Description Remark
detInfo Detection of buses and high-speed vehicles Mandatory
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ISO 10711:2012(E)
The information identified in Table 10 denotes the data element of Det-Status in Table 6, Table 7, and
Table 17.
Table 10 — Detection status information
Data element name Description
Normal Shows normal detection
Failure Shows detector failure
DataInvalid Shows invalid data (for example, data just after reboot of detector)
Table 11 — Detector status message set
Item name Description Remark
IDetStatus Status of processing and operating Optional
The item (IDetStatus) in Table 11 is encoded as follows.
Table 12 — Detector status information
Data element name Value Domain
Processing Status Flag 0: n
...