ISO 16785:2026

• Abstract:

  This document specifies requirements for an application interface between dedicated short-range communication on-board equipment (DSRC-OBE) and external in-vehicle devices to make DSRC-OBE applicable for diversified electronic fee collection (EFC) systems. This document applies to: — definitions of the application interface between DSRC-OBE and external in-vehicle devices; — definitions of data groups and data elements.

• Status: Published
• Publication Date: 18-Aug-2026
• ICS: 03.220.20 - Road transport
• ICS: 35.240.60 - IT applications in transport
• Technical Committee: ISO/TC 204 - Intelligent transport systems
• Drafting Committee: ISO/TC 204/WG 5 - Fee and toll collection
• Current Stage: 6060 - International Standard published
• Start Date: 19-Aug-2026
• Due Date: 31-Oct-2026
• Completion Date: 19-Aug-2026

• Revises: ISO/TS 16785:2020 - Electronic Fee Collection (EFC) — Application interface definition between DSRC-OBE and external in-vehicle devices
• Effective Date: 04-Nov-2023

ISO 16785:2026 is an International Standard published by ISO for electronic fee collection (EFC). ISO 16785:2026 specifies the application interface between dedicated short-range communication on-board equipment (DSRC-OBE) and external in-vehicle devices so DSRC-OBE can be used in diversified EFC systems. It is written for organizations that design, supply, integrate, test, or assess DSRC-OBE and the in-vehicle devices that extend it.

What does ISO 16785:2026 specify?

ISO 16785:2026 specifies the interface definition, data groups, and data elements used between DSRC-OBE and external in-vehicle devices. The document is focused on how the two sides exchange application data for tolling-related functions, not on the hardware itself.

The scope is organized into seven clauses and three annexes:

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	Symbols and abbreviated terms
Clause 5	Tolling models with the in-vehicle devices
Clause 6	ADUs descriptions
Clause 7	Security aspects
Annex A	Data type specification
Annex B	Protocol implementation conformance statement proforma
Annex C	Clarification of data elements

ISO 16785:2026 does not cover the internal design of external in-vehicle hardware, the physical interface between devices, value-added services (VAS), or the authentication, encryption, and key-management algorithms themselves. In practice, that means the standard tells implementers what data and interface behavior must exist, while leaving product architecture and security algorithm choices to other specifications or to the implementer’s design.

What are the key requirements of ISO 16785:2026?

ISO 16785:2026 defines a tolling model in which DSRC-OBE works with external in-vehicle devices to support both DSRC-based EFC and autonomous EFC. This matters because the same on-board equipment can be reused across different tolling environments instead of being replaced when a new road-charging scheme is introduced.

• The operating environment in Clause 5.2.1 assumes an external in-vehicle device set that includes, at minimum, a GNSS receiver and a cellular network (CN) mobile device. Optional components include HMI, motion sensors, a digital tachograph interface, and a CAN, OBD-II interface. For implementers, this means the interface has to fit both a minimum configuration and richer vehicle integrations.
• The tolling model distinguishes the roles of RSE(L) for localization augmentation, RSE(C) for compliance checking, and RSE(T) for tolling. DSRC-OBE exchanges DSRC-related data with these roadside elements, while the external in-vehicle device exchanges autonomous EFC data with the toll service provider (TSP) back end through cellular networks. This separation is important for system design and for deciding which function belongs to roadside communication and which belongs to the in-vehicle platform.
• Clause 5.2.3 defines APDU-based exchange using the ASN.1 structure InfoExchangeObe. The mandatory payload is InfoExchangeObeContent, which contains apciObe and adusObe, and an optional authenticator can be attached. In practice, the standard is fixing the content and structure of the exchanged application messages so different suppliers can interoperate.
• The ADU set in Clause 5.2.3 covers paymentMeansStatusAdus, accountUpdateAdus, paymentFeeAdus, cccAttributesAdus, and lacDataAdus. Some are optional and some are mandatory, so a supplier must implement the required ADUs for the intended role and support the relevant data types from the referenced standards. This is the core of the interface definition.
• Clause 5.3 requires conformance identification through the Protocol Implementation Conformance Statement (PICS) in Annex B. Both suppliers of external in-vehicle devices and suppliers of DSRC-OBE complete the proforma to state what is implemented. This gives buyers and test labs a standardized way to check claimed support.
• Clause 6 defines the content of the main ADUs. PaymentMeansStatus carries payment mode, account status, payment means, balance, unit, and security data; AccountUpdate supports reload, set, and add operations with authenticated variants. For a project team, this clause tells you what account and payment state must be represented and what updates can be requested.
• Clause 7 sets security expectations for authenticated entities, confidentiality, and integrity, and it points to mutual authentication based on ISO/IEC 9798-4. For deployment, this means the interface is treated as security-sensitive and should be evaluated accordingly, even though the algorithm details are outside the document.

What terms does ISO 16785:2026 define?

ISO 16785:2026 uses the terms and abbreviations in Clause 3 and Clause 4, with the definitions taken from ISO 17573-2. A few key ones are:

• ADU - application data unit, the data package exchanged for a specific application action.
• APDU - application protocol data unit, the higher-level exchange unit used between DSRC-OBE and the external in-vehicle device.
• DSRC - dedicated short-range communication, the communication family used by the on-board equipment and roadside equipment.
• OBE - on-board equipment, the vehicle equipment that participates in tolling communication.
• PICS - protocol implementation conformance statement, the completed statement used to show what an implementation supports.
• CCC - compliance check communication, the data used for compliance checking in autonomous systems.
• LAC - localization augmentation communication, the data used to improve position-related functions.

Who uses ISO 16785:2026?

ISO 16785:2026 is used by DSRC-OBE manufacturers, suppliers of external in-vehicle devices, and integrators who combine GNSS, CN, HMI, and vehicle interfaces into one tolling platform. It is also relevant to toll service providers (TSP), toll chargers (TC), and test laboratories that need to confirm interoperability.

In practice, the standard helps teams that design autonomous EFC upgrades, extend DSRC-based tolling to new roads, or build vehicle equipment that has to work across several tolling environments. Quality managers and buyers use it to compare claimed support against the PICS tables and to check whether a product supports the required ADUs and security-related behavior.

What changed in ISO 16785:2026 from the previous edition?

ISO 16785:2026 is the first edition and it cancels and replaces ISO/TS 16785:2020. The foreword states that it has been technically revised.

The stated changes are:

• Clause 3 was updated, and ISO 17573-2 became the primary source for terms and definitions.
• Information on application data units (ADUs) for information exchange between DSRC-OBE and external in-vehicle devices was added.
• The description of the external in-vehicle device in Clause 5.2.1 was modified.
• The ASN.1 code was modified, with Annex A and the attached ASN.1 file updated.
• Data elements for compliance checking communication imported from ISO 12813 were revised.
• The charge report and the reference to ISO 17575-1 were deleted.

Which standards are used with ISO 16785:2026?

ISO 16785:2026 uses several companion standards to define the data it exchanges and the way that data is encoded:

• ISO/IEC 8825-2 - provides Packed Encoding Rules (PER) for ASN.1 encoding, which Annex A uses.
• ISO 12813 - provides compliance check communication content used for CCC attributes.
• ISO 12855 - provides information exchange between service provision and toll charging, used for payment and account-related data.
• ISO 13141 - provides localization augmentation communication content used for LAC data.
• ISO 15628:2013 - provides the DSRC application layer and its ASN.1 encoding restrictions.
• ISO 17573-2 - provides the EFC vocabulary used in the terminology.
• ISO 17573-3 - provides the EFC data dictionary for items such as PaymentFee, AccountStatus, and PaymentMeans.

Annex A also relies on ISO/IEC 8824-1 for ASN.1 notation, while the security section points to ISO 19299 and ISO/IEC 9798-4 for security framework and entity authentication concepts.

What does the ISO 16785:2026 document contain?

ISO 16785:2026 contains a tolling model, APDU and ADU structures, and the data elements needed for payment means status, account update, payment fee, CCC attributes, and LAC data. Clause 5 includes figures that show the operating environment and data exchanges, plus tables that classify the external in-vehicle device configurations and the APDU/ADU contents.

Clause 6 gives the detailed data structures for PaymentMeansStatus and AccountUpdate, including the PaymentMode values and the authenticated update elements. Annex A provides the ASN.1 module and the SHA-256 reference for the attached ASN.1 file, which is what implementers use when generating or checking encoded data. Annex B provides the PICS proforma tables used for conformity statements, and Annex C explains how the data groups relate to the wider EFC system, including CCC attributes and LAC data flows.

International
Standard
ISO 16785
First edition
Electronic fee collection —
2026-08
Application interface definition
between dedicated short-range
communication on-board
equipment (DSRC-OBE) and
external in-vehicle devices
Perception de télépéage — Définition de l'interface entre
l'équipement de bord à communications dédiées à courte portée
(DSRC-OBE) et des dispositifs externes embarqués
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms. 2
5 Tolling models with the in-vehicle devices . 3
5.1 General .3
5.2 Tolling model .3
5.2.1 Operating environment .3
5.2.2 Data exchanges .5
5.2.3 Application protocol data units.6
5.3 Conformance .9
5.3.1 Conformance requirements .9
5.3.2 Conformance statement .9
6 ADUs descriptions . 10
6.1 General .10
6.2 PaymentMeansStatus ADU data structure .10
6.2.1 General .10
6.2.2 PaymentMode .10
6.3 AccountUpdate ADU data structure .11
6.3.1 General .11
6.3.2 ReloadAccount .11
6.3.3 NewAccountLimit . 12
6.3.4 AddToAccount . 12
6.3.5 AuthenticatedReloadAccount . 13
6.3.6 AuthenticatedNewAccountLimit . 13
6.3.7 AuthenticatedAddToAccount . 13
7 Security aspects .13
7.1 General . 13
7.2 OBE interface profile . 13
Annex A (normative) Data type specification.15
Annex B (normative) Protocol implementation conformance statement proforma .16
Annex C (informative) Clarification of data elements .20
Bibliography .22

iii
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,
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
This first edition cancels and replaces the second edition (ISO/TS 16785:2020), which has been technically
revised.
The main changes are as follows:
— Clause 3 has been updated and ISO 17573-2 has been made the primary source for terms and definitions;
— addition of information regarding the application data units (ADUs) for information exchange between
dedicated short-range communication on-board equipment (DSRC-OBE) (see Clause 6);
— modification of information regarding the external in-vehicle device (see 5.2.1);
— modification of the ASN.1 code; see Annex A and attached ASN.1 file;
— revision of data elements related to compliance checking communication imported from ISO 12813 (see
5.2.3);
— deletion of the charge report and reference to ISO 17575-1.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
0.1  Background and motivation
For sustainable road environment, the road tolling policy in different regions of the world has spread
from conventional road tolling, such as funding for road infrastructure management and maintenance,
environmental measures, and traffic management, to other aspects. Specifically, to accommodate the
widespread use of low-fuel-consumption and electric vehicles, introduction of road user charging instead of
fuel tax, congestion tolling on urban roads and inter-urban roads is planned and implemented.
In the countries where dedicated short-range communication (DSRC) based electronic fee collection (EFC)
systems are widely deployed, upgrading and extension of the schemes, to include roads that are currently
not tolled become a significant issue to consider.
This document describes how DSRC-based EFC systems, especially on-board equipment (OBE), can be
enhanced to meet these needs.
There are three cases of introducing EFC systems to cope with these situations:
— Case-1: An existing DSRC-based EFC system is extended and introduced on new roads.
— Case-2: An autonomous EFC system is introduced on both new roads and the existing toll roads.
— Case-3: A DSRC-based EFC system continues to operate on existing toll roads, and an autonomous EFC
system is introduced on new toll roads.
For Case-1 and Case-2, the interface definitions and the test procedures are defined by existing EFC
standards. For Case-3 as shown in Figure 1, the OBE used for DSRC-based EFC can also be used for the
autonomous EFC system covering new roads and existing toll roads.
A DSRC-OBE can be applied in new EFC environments consisting of DSRC-based EFC and the autonomous
EFC system by expanding its functionality by interfacing with the external in-vehicle devices that includes
a global navigation satellite system (GNSS) module, cellular network communication (CN) module and other
related modules.
Consequently, an application interface definition between DSRC-OBE and the external in-vehicle devices is
described in this document.
Figure 1 — Image of expanding toll roads and services (Case-3)

v
0.2  Purpose of this document
The purpose of this document is to provide support for enhanced functionalities of DSRC-OBE by means of
external in-vehicle devices.
This document intends to define:
— a tolling model with the external in-vehicle devices (see in subclause 5.2);
— data groups and data elements (see Clauses 5 and 6);
— data types and the protocol implementation conformance statement (PICS) proforma (in Annexes A
and B).
0.3  Applicable dedicated short-range communication on-board equipment (DSRC-OBE)
There are five major DSRC standards currently being deployed for EFC around the world: CEN-DSRC, UNI-
DSRC, ARIB-DSRC, TTA-DSRC and GB-DSRC. In standardizing an application interface between DSRC-OBE
and an external in-vehicle devices, the interface should be applied for every type of DSRC as shown in
Figure 2.
Figure 2 — Applicable DSRC-OBE
Due to its operational reliability, DSRC-OBE is suitable for EFC. On the other hand, each component of
an external in-vehicle devices typically has a shorter product life than DSRC-OBE to meet changing user
demands for multi-functional and high-performance components.
Once an application interface has been standardized, DSRC-OBE can be used seamlessly in a variety of EFC
environments with an enhanced new external in-vehicle devices as shown in Figure 3.
Figure 3 — Applicability for future upgrading

vi
International Standard ISO 16785:2026(en)
Electronic fee collection — Application interface definition
between dedicated short-range communication on-board
equipment (DSRC-OBE) and external in-vehicle devices
1 Scope
This document specifies requirements for an application interface between dedicated short-range
communication on-board equipment (DSRC-OBE) and external in-vehicle devices to make DSRC-OBE
applicable for diversified electronic fee collection (EFC) systems.
This document applies to:
— definitions of the application interface between DSRC-OBE and external in-vehicle devices;
— definitions of data groups and data elements.
The scope of this document is illustrated in Figure 4:
Figure 4 — Scope of this document
This document is not applicable to:
— definitions of hardware components in the external in-vehicle devices such as GNSS receiver, CN mobile
device;
— definitions of the physical interface between DSRC-OBE and the external in-vehicle devices;
— definition of value-added services (VAS);
— definition of algorithms for authentication, encryption and key management for security aspect.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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/IEC 8825-2, Information technology — ASN.1 encoding rules — Part 2: Specification of Packed Encoding
Rules (PER)
ISO 12813, Electronic fee collection — Compliance check communication for autonomous systems
ISO 12855, Electronic fee collection — Information exchange between service provision and toll charging
ISO 13141, Electronic fee collection — Localization augmentation communication for autonomous systems
ISO 15628:2013, Intelligent transport systems — Dedicated short range communication (DSRC) — DSRC
application layer
ISO 17573-2, Electronic fee collection — System architecture for vehicle related tolling — Part 2: Vocabulary
ISO 17573-3, Electronic fee collection — System architecture for vehicle-related tolling — Part 3: Data dictionary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17573-2 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols and abbreviated terms
ADU application data unit
APDU application protocol data unit
ARIB Association of Radio Industries and Businesses
NOTE 1 ARIB is a communication standardization organization in Japan.
ASN.1 abstract syntax notation one
CAN controller area network
CCC compliance check communication
CN cellular network
DSRC dedicated short-range communication
EFC electronic fee collection
GB Guojia Biaozhun
NOTE 2 GB is a national standard published by Standardization Administration of China.
GNSS global navigation satellite system
HMI human-machine interface
IUT implementation under test
LAC localization augmentation communication
OBE on-board equipment
OBD on-board diagnostics
OBU on-board unit
PICS protocol implementation conformance statement
RSE roadside equipment
TC toll charger
TSP toll service provider
TTA Telecommunications Technology Association
NOTE 3 TTA is a communication standardizing body in the Republic of Korea.
UNI Ente Nazionale Italiano di Unificazione
NOTE 4 UNI is a communication standardizing body in Italy.
URL uniform resource locator
VAS value added services
5 Tolling models with the in-vehicle devices
5.1 General
The DSRC-OBE with the external in-vehicle devices can support various EFC environments and further VAS
as shown in Figure 1.
There are two kinds of settlement method in EFC, one is the on-board account system, and the other method
is the central account system. In the case of on-board account system, payment means may be connected
to DSRC-OBE as shown in Figure 5, and the toll amount determined by the tolling transaction processes
is directly deducted from payment means in the case of pre-payment. In the case of post payment system,
the toll amount is posted to the central system with a personal account number transmitted from payment
means.
Figure 5 — Arrangement of payment means
5.2 Tolling model
5.2.1 Operating environment
The system in which DSRC-OBE is connected to the external in-vehicle devices should support the diversified
tolling system that supports both the autonomous EFC system and DSRC-based EFC system as shown in
Figure 6. In the figure, RSE(L), RSE(C) and RSE(T) are equipment to communicate with DSRC-OBE via DSRC
communication. RSE(L) is used for localization checking by toll charger (TC) to verify the existence of the

vehicle in the serviced area. RSE(C) is used for compliance checking done by TC to verity the validity of
OBE via DSRC communication. The information can be exchanged through these transactions with the toll
service provider (TSP) via the external in-vehicle device.
NOTE RSE(T) is used for DSRC tolling by TC, no relation with the external in-vehicle device.
Key
RSE(L) RSE for localization augmentation via DSRC communication
RSE(C) RSE for compliance checking via DSRC communication
RSE(T) RSE for tolling via DSRC communication
Figure 6 — Tolling model for the diversified tolling
In the diversified tolling system, the external in-vehicle devices consist of the various components listed in
Table 1.
Table 1 — Configurations for tolling system
Tolling system DSRC-OBE Major components of the external in-vehicle devices
GNSS re- CN mobile HMI Motion Interfaces to vehicle
ceiver device sensors
Digital CAN
tachograph (OBD-II)
DSRC-based EFC m — — — — — —
Autonomous tolling m m m o o o o
m: mandatory, o: option, —: not applicable

As a minimum configuration, the external in-vehicle devices should include GNSS receiver and CN mobile
device. The following components should be considered as optional parts for implementation that depends
on the requirements of autonomous EFC system:
a) HMI;
b) motion sensors;
c) digital tachograph interface;
d) controller area network’s on-board diagnostics (CAN, OBD-II) interface.
The external in-vehicle devices shall connect to the back end of the TSP to exchange the required autonomous
EFC related data through cellular networks. DSRC-OBE shall be connected with individual RSE that exchange
the related data for DSRC tolling, compliance check and localization through DSRC.
Whereas Figure 6 shows the configuration in which the external in-vehicle devices and DSRC-OBE are
physically separated, these can be integrated into a single OBE device.
5.2.2 Data exchanges
Figure 7 shows the general data exchanges between the external in-vehicle devices and the DSRC-OBE. As
shown in the figure, external in-vehicle devices and the DSRC-OBE transfer the following information:
— information exchanged between TSP (back end) and DSRC-OBE, e.g. charge report, charge report
response, context data and context data response;
— information exchanged between DSRC-OBE as a processing result done by TC and the external in-vehicle
devices, e.g. payment means status, account update, payment fee, compliance check communication
(CCC) and localization augmentation communication (LAC) data.
For the communications, this document defines data interface between the external in-vehicle devices and
DSRC-OBE.
The relationship of the data groups in the entire EFC system is explained in Annex C.

Key
RSE(L) RSE for localization augmentation via DSRC communication
RSE(C) RSE for compliance checking via DSR communication
RSE(T) RSE for tolling via DSRC communication
Figure 7 — Data exchanges for the diversified tolling
5.2.3 Application protocol data units
Between the DSRC-OBE and the external in-vehicle devices, information exchanges are performed by means
of APDU transfers.
The structure of the APDU is shown in Figure 8.

Figure 8 — Structure of APDU (InfoExchangeObe)
The ASN.1 data type that shall be used can be found via the URL in Annex A.
The APDU is specified as ASN.1 data type InfoExchangeObe, which is described in Table 2.
Table 2 — Data elements of InfoExchangeObe
Data element Data type/data description Status
infoExchangeObeContent
InfoExchangeObeContent (see Table 3). m
This data element shall contain the actual content of the
APDU.
infoExchangeAuthenticator
Data type is AuthenticatorEfc. Record (ASN.1 SEQUENCE) o
made of three fields of types tbsAuthenticatorEfc,
signatureAlgorithm and signatureValue.
This data element may optionally contain an authen-
ticator calculated over the content of data element
infoExchangeContent
m: mandatory, o: option, —: not applicable
The mandatory data type InfoExchangeContent is described in Table 3.
Table 3 — Data elements of InfoExchangeObeContent
Data element Data type/data descri
...