UN Regulation No. 157 — Uniform provisions concerning the approval of vehicles with regard to Automated Lane Keeping Systems

Overview

UN Regulation No. 157 on Automated Lane Keeping Systems (ALKS) represents a landmark international standard, being the first binding regulation globally for the introduction of Level 3 vehicle automation. Adopted by the World Forum for Harmonization of Vehicle Regulations (WP.29) under the United Nations Economic Commission for Europe (UNECE), this regulation establishes uniform provisions for the type approval of vehicles equipped with ALKS. Its primary intention is to ensure the safety and reliability of these advanced driving systems, which control the lateral and longitudinal movement of a vehicle for extended periods without requiring continuous driver command. The regulation initially applied to passenger cars (M1 vehicles) and limited operational speed to 60 km/h, primarily for traffic jam situations. However, recognizing the rapid advancements in automated driving technology and the need for broader applicability, the regulation has undergone significant amendments. The 01 series of amendments, which came into force in January 2023, expanded the scope to include vehicles of classes M and N and notably increased the maximum operational speed to 130 km/h. This extension also introduced provisions for automated lane changes and the use of ALKS in vehicle combinations, marking a crucial step towards more comprehensive automated driving functionalities on highway-like roads. The regulation places a strong emphasis on the system's ability to maintain primary control while ensuring the driver remains available to take back control when prompted, outlining strict requirements for safe transition demands and minimum risk manoeuvres.

The development of UN Regulation No. 157 was guided by UNECE's overarching framework on automated and autonomous vehicles, which prioritizes safety in the regulatory work for future mobility. It provides a clear framework for Original Equipment Manufacturers (OEMs) and vehicle manufacturers to develop and implement SAE Level 3 automated driving systems in series-production vehicles for international markets. Beyond the core technical requirements for ALKS functionality, the regulation also mandates compliance with other critical UNECE regulations, specifically UN R155 concerning cybersecurity and UN R156 regarding software updates. This integrated approach ensures that ALKS-equipped vehicles not only perform their driving tasks safely but are also resilient against cyber threats and maintain their safety and functionality through controlled software modifications. The regulation's comprehensive nature, covering performance-based requirements, technical specifications, audit procedures, documentation, and rigorous proving ground tests, aims to build trust among consumers regarding the safety of automated lane keeping systems.

Definitions

UN Regulation No. 157 establishes clear definitions for key terms to ensure consistent understanding and application across contracting parties and manufacturers. An "Automated Lane Keeping System" (ALKS) is defined as a system that controls the lateral and longitudinal movement of the vehicle for extended periods without further driver command, where the activated system is in primary control of the vehicle. This aligns with the Society of Automotive Engineers (SAE) Level 3 of driving automation, often referred to as "conditionally automated driving," where the automated driving system performs the entire dynamic driving task under specific conditions, but the human driver must be ready to take over when requested. A critical concept is the "Transition Demand," which is a signal issued by the ALKS to the driver, indicating that the system is no longer able to continue the dynamic driving task and requests the driver to take over manual control. The regulation specifies strict requirements for the timing and nature of such demands to ensure driver readiness and safe handover.

Another important term is "Minimum Risk Manoeuvre" (MRM), which refers to a procedure automatically initiated by the ALKS in situations where the system encounters a severe vehicle or system failure, or when the driver fails to respond appropriately to a transition demand. The MRM aims to bring the vehicle to a safe stop or to a minimal risk condition, thereby mitigating potential hazards. The regulation also introduces the requirement for a "Data Storage System for Automated Driving" (DSSAD), essentially a "black box" that records crucial data points, such as when the ALKS is activated, when transition demands are issued, and when lane changes are initiated by the system. This data is vital for accident reconstruction, liability assessment, and continuous improvement of ALKS safety. Furthermore, the regulation addresses the "Human-Machine Interface" (HMI), setting requirements to prevent driver misunderstanding or misuse of the system, including provisions for automatically suspending on-board displays used for non-driving activities when a transition demand is active.

Governance and Institutional Framework

The governance and institutional framework for UN Regulation No. 157 is rooted in the United Nations Economic Commission for Europe (UNECE) and its World Forum for Harmonization of Vehicle Regulations (WP.29). WP.29 is a unique global platform responsible for establishing regulatory frameworks concerning the safety and environmental performance of vehicles, their subsystems, and parts. It operates under the framework of three global agreements, with UN Regulation No. 157 falling under the 1958 Agreement, which facilitates the reciprocal recognition of approvals granted on the basis of UN Regulations among its contracting parties. This mechanism allows for a harmonized approach to vehicle type approval, reducing technical barriers to trade and ensuring consistent safety standards across participating countries. WP.29 convenes three times a year, bringing together representatives from member countries, regional economic integration organizations, and non-governmental organizations to discuss, develop, and amend UN Regulations.

The technical development and drafting of UN Regulation No. 157, including its subsequent amendments, are primarily conducted by subsidiary working groups under WP.29. Specifically, the Working Party on Automated/Autonomous and Connected Vehicles (GRVA) plays a crucial role in preparing global provisions for automated and autonomous vehicles. GRVA develops proposals for new regulations or amendments based on consensus among experts, which are then submitted to WP.29 for adoption. This collaborative process, involving governmental and industry experts, ensures that the regulations are technically sound, reflect the latest technological advancements, and address real-world safety challenges. The transparency of WP.29's work, with all agendas, working documents, and reports openly accessible on its website, further reinforces its role as a credible and influential body in international vehicle regulation. The framework ensures that regulations like UN R157 are not static but evolve through continuous review and amendment processes to keep pace with the dynamic nature of automotive technology and emerging safety considerations.

Key Focus Areas

UN Regulation No. 157 focuses on several critical areas to ensure the safe and reliable operation of Automated Lane Keeping Systems (ALKS). A primary focus is on the operational design domain (ODD) of ALKS, specifying that these systems can only be activated under certain conditions on roads where pedestrians and cyclists are prohibited and which are, by design, equipped with a physical separation dividing opposing traffic. This ensures that ALKS operates in controlled environments, minimizing interactions with vulnerable road users. Initial versions of the regulation limited the operational speed to 60 km/h, suitable for traffic jam scenarios, but the 01 series of amendments significantly increased this to 130 km/h, expanding the system's utility to highway driving. This higher speed capability necessitates more robust sensor systems and response capabilities, which are detailed within the regulation, including minimum forward, lateral, and rearward detection ranges.

Another key area is the interaction between the ALKS and the driver, particularly the Human-Machine Interface (HMI) and the transition of control. The regulation mandates that the driver must always be in a position to respond to a takeover request from the system and sets requirements for a driver availability recognition system. This system monitors the driver's presence and their readiness to take back control, ensuring that the driver remains attentive enough to intervene when necessary. In cases where the driver fails to respond appropriately to a transition demand, the ALKS must be capable of initiating a Minimum Risk Manoeuvre (MRM) to bring the vehicle to a safe stop. The HMI requirements also include provisions for automatically suspending on-board displays used for non-driving activities when the ALKS issues a transition demand, preventing driver distraction during critical handover periods. Furthermore, the regulation includes stringent requirements for collision avoidance, stipulating that the activated system shall not cause any reasonably foreseeable and preventable collisions and must avoid collisions if it can do so safely without causing another. The integration of a Data Storage System for Automated Driving (DSSAD) is also a crucial focus, acting as a 'black box' to record essential data for post-event analysis and liability determination. Finally, the regulation emphasizes compliance with UN R155 (Cybersecurity) and UN R156 (Software Updates) to ensure the overall security and integrity of ALKS throughout their lifecycle.

Implementation Framework

The implementation framework for UN Regulation No. 157 is built upon the principles of type approval, which is a system used internationally to ensure that vehicles, their systems, and components meet specific technical and safety standards before being placed on the market. Under the 1958 Agreement, to which many countries are Contracting Parties, manufacturers seeking to introduce ALKS-equipped vehicles must demonstrate compliance with UN R157 to a national type approval authority. This involves submitting detailed documentation, technical specifications, and undergoing rigorous testing procedures. Once a vehicle type receives approval from one Contracting Party, that approval is reciprocally recognized by other Contracting Parties, streamlining the market entry process for manufacturers across multiple jurisdictions. This harmonization significantly reduces the regulatory burden and fosters international trade in advanced vehicle technologies.

For manufacturers, the implementation of UN R157 requires a comprehensive approach to design, development, and validation. They must ensure that the ALKS meets all performance-based requirements, including those related to operational conditions, speed limitations, driver monitoring, HMI, and failsafe responses. The regulation's emphasis on cybersecurity (UN R155) and software updates (UN R156) means that manufacturers must also implement robust processes for securing the ALKS against cyber threats and managing software changes throughout the vehicle's lifespan. The role of technical services is integral to this framework, as they conduct the necessary inspections, audits, and tests to verify the manufacturer's claims of compliance. The ongoing development of the regulation, through amendments like the 01 series, means that manufacturers must continuously adapt their designs and compliance strategies to meet evolving requirements, such as increased speed limits and lane change capabilities. The transitional provisions within the regulation specify dates by which compliance becomes mandatory for new types of ALKS-equipped vehicles and for all ALKS-equipped vehicles, providing a clear roadmap for industry adoption.

Monitoring and Evaluation

Monitoring and evaluation of compliance with UN Regulation No. 157 are critical to ensuring the ongoing safety and performance of Automated Lane Keeping Systems. The regulation outlines a multi-faceted approach, primarily centered around the type approval process. During this initial stage, manufacturers must demonstrate to a technical service that their ALKS-equipped vehicles meet all the specified requirements through a combination of documentation, audits, and physical tests. This includes detailed technical specifications of the ALKS, a comprehensive safety approach, and evidence of rigorous testing under various scenarios, including proving ground tests and simulated real-world conditions. The technical service, acting on behalf of the type approval authority, verifies the functionality and performance of the ALKS, including its ability to handle transition demands, execute minimum risk manoeuvres, and avoid collisions.

Beyond the initial type approval, ongoing monitoring and evaluation are implicitly supported by several aspects of the regulation. The mandatory inclusion of a Data Storage System for Automated Driving (DSSAD) serves as a crucial tool for post-incident analysis. In the event of an accident or system malfunction, the data recorded by the DSSAD can be retrieved to understand the system's state, driver's actions, and the sequence of events leading to the incident. This data is invaluable for identifying potential safety gaps, informing future amendments to the regulation, and contributing to continuous improvement in ALKS design. Furthermore, the requirement for compliance with UN R156 on software updates implies a need for manufacturers to maintain records of software versions and changes, allowing for traceability and evaluation of the impact of updates on system performance. The World Forum for Harmonization of Vehicle Regulations (WP.29) itself acts as a continuous monitoring body, regularly reviewing and amending UN Regulations based on new research, technological advancements, and real-world experience, ensuring that the regulatory framework remains relevant and effective.

Penalties, Liability, and Appeals

UN Regulation No. 157, like other UN Regulations, primarily establishes uniform technical provisions for the type approval of vehicles. It sets the technical standards that Automated Lane Keeping Systems (ALKS) must meet to be approved for use. However, the regulation itself does not directly specify penalties for non-compliance, nor does it lay down a comprehensive framework for civil or criminal liability, or appeal processes. These aspects are generally left to the national legislation of the individual Contracting Parties that apply the UN Regulation. Each country is responsible for enacting its own laws and regulations to enforce the UN standards, including defining penalties for manufacturers who fail to comply with type approval requirements and establishing legal frameworks for liability in cases involving ALKS-equipped vehicles. This approach allows national legal systems to integrate the technical requirements of UN R157 into their existing legal structures for product liability, road traffic offenses, and consumer protection.

Despite not directly addressing liability, UN Regulation No. 157 provides crucial elements that will inform national liability frameworks. The regulation's clear delineation of responsibilities, particularly regarding the ALKS being in "primary control" of the vehicle while the driver remains "available" to take over, is fundamental. The requirements for the Human-Machine Interface (HMI), transition demands, and minimum risk manoeuvres establish specific performance expectations for both the system and the driver, which can be critical in determining fault or responsibility in an incident. Moreover, the mandatory Data Storage System for Automated Driving (DSSAD) is a vital tool for liability assessment. By recording key operational data, the DSSAD provides objective evidence of whether the ALKS was active, when transition demands were issued, and how the system and driver responded, which can be used in legal proceedings to establish facts and assign liability. While the regulation sets the technical baseline for safe ALKS operation, the ultimate responsibility for establishing and enforcing penalties, determining liability, and providing appeal mechanisms rests with the national governments that have adopted and implemented UN R157 into their domestic legal systems.

Relationship to Other Instruments

UN Regulation No. 157 does not exist in isolation but is part of a broader ecosystem of international and national legal instruments governing vehicle safety and automated driving. It is specifically developed and administered by the UNECE World Forum for Harmonization of Vehicle Regulations (WP.29) under the 1958 Agreement, which aims to create a globally harmonized regulatory framework for vehicles. This means that while UN R157 sets specific technical requirements for Automated Lane Keeping Systems, it is designed to be consistent with and complementary to other UN Regulations. Notably, UN R157 is intrinsically linked to two other crucial UNECE regulations: UN Regulation No. 155 on Cybersecurity and Cybersecurity Management System, and UN Regulation No. 156 on Software Update and Software Update Management System. Compliance with both UN R155 and UN R156 is mandatory for ALKS-equipped vehicles seeking type approval under UN R157, ensuring that automated systems are not only functionally safe but also resilient against cyber threats and maintain their integrity through controlled software modifications.

Furthermore, UN Regulation No. 157 is a foundational step within UNECE's broader framework for automated and autonomous vehicles. This framework aims to progressively introduce regulations for higher levels of automation, with WP.29's Working Group on Automated/Autonomous and Connected Vehicles (GRVA) continually preparing global provisions for more advanced automation levels, such as SAE Level 4. The regulation also interacts with national road traffic laws and regulations in Contracting Parties. While UN R157 sets technical standards for the vehicle system, national laws govern driver behavior, road rules, and the legal operational conditions for ALKS on public roads. The regulation explicitly states that its measures are without prejudice to driver behaviour rules on how to use these systems in the Contracting Parties, acknowledging the ongoing discussions by bodies like the Global Forum for Road Traffic Safety (WP.1) on integrating automated driving systems into existing traffic rules. This layered approach ensures that international technical standards are harmonized with national legal and operational frameworks, creating a comprehensive regulatory environment for automated driving.

International Alignment

International alignment is a core objective and a significant achievement of UN Regulation No. 157. Developed by the UNECE World Forum for Harmonization of Vehicle Regulations (WP.29), it represents the first internationally agreed-upon regulation for SAE Level 3 automated driving systems. The regulation's adoption by 42 countries initially, and its subsequent application by 54 Contracting Parties to the 1958 Agreement, underscores its global significance in establishing uniform type approval requirements for ALKS. This harmonization is crucial for the automotive industry, as it provides a consistent legal framework for manufacturers developing automated driving functions for international markets, thereby reducing the complexity and cost associated with complying with diverse national regulations. By setting a common standard for safety and performance, UN R157 facilitates the cross-border deployment of ALKS-equipped vehicles and promotes consumer confidence in these advanced technologies worldwide.

The continuous evolution of UN Regulation No. 157, through its 01 series of amendments and subsequent supplements, further demonstrates the commitment to international alignment. The process involves extensive collaboration among experts from various countries, industry stakeholders, and technical organizations within the WP.29 framework, particularly through the Working Party on Automated/Autonomous and Connected Vehicles (GRVA). This collaborative approach ensures that the regulation remains technologically neutral where possible, adaptable to regional specificities, and responsive to emerging safety concerns and technological advancements. The reciprocal recognition of type approvals granted under the 1958 Agreement is a direct benefit of this alignment, allowing vehicles approved in one Contracting Party to be accepted in others, fostering a global market for ALKS technology. This international cooperation not only enhances road safety and environmental protection through shared standards but also promotes innovation by providing a clear and stable regulatory environment for the development and deployment of cutting-edge automotive technologies on a global scale.

Implementation Timeline

Compliance Checklist

Sources and References