In the era of Software-Defined Vehicles (SDVs), the world’s dual driving conventions, the right-hand and left-hand drive, present unforeseen complexities. While traditional vehicles simply mirrored controls to suit regional norms, SDVs must integrate vast, localised datasets, encompassing everything from road rules and signage to traffic behaviour and infrastructure design in order to navigate safely across jurisdictions.
This complexity intensifies as ADAS (Advanced Driver Assistance Systems), V2X (Vehicle-to-Everything) communication, and autonomous capabilities become more prevalent. These systems are highly sensitive to local road conventions, requiring OEMs and SDV platforms to engineer for seamless cross-border adaptability.
“As SDVs gain traction, this historical bifurcation underscores the need for region-aware vehicle intelligence and infrastructure harmonization,” says Sundar Ganapathi, Chief Technology Officer – Automotive, Tata Elxsi.
He explains, “The coexistence of left- and right-hand driving significantly affects new-age vehicles, especially those equipped with V2V (Vehicle-to-Vehicle) and V2X (Vehicle-to-Everything) communication technologies, which depend on real-time spatial awareness and synchronised signalling.”
Consider aspects like lane-change algorithms, overtaking behaviour, and roundabout navigation, they vary significantly based on which side of the road is the standard. “Without harmonisation, vehicles may misinterpret manoeuvres or prioritise incorrect threat vectors. This becomes more critical with SDVs, where split-second decisions are made based on digital input rather than human instinct,” Ganapathi emphasizes.
A Historical Split, A Modern Challenge
Historically, the choice between left-hand and right-hand drive stems from colonial, military, and trade influences. India, for example, retained the British practice of left-hand traffic (LHT), while the U.S. adopted right-hand traffic (RHT) for logistical efficiency in wagon and later automotive design. Today, about 65% of the world, including the U.S., China, and most of Europe follow RHT with left-hand drive (LHD) vehicles, whereas countries like India, the UK, Australia, and Japan follow LHT with right-hand drive (RHD) vehicles.
This global split makes RHT-LHD the majority standard, creating technical efficiencies for SDV development, as most autonomous driving software, simulation models, and datasets are trained and validated in RHT regions.
“The geographic fragmentation creates interoperability challenges for autonomous systems, especially those involving cross-border logistics or vehicle exports,” notes Ganapathi. While switching a country’s driving orientation is an enormous infrastructural and cultural undertaking, historically, only a few nations, such as Sweden in 1967, have transitioned. Today, such changes are rare due to cost and complexity.
“Regulators are more inclined to mandate region-specific compliance for SDVs than overhaul national traffic systems. Therefore, while logically consolidating to a single driving norm may seem efficient, the pragmatic solution lies in creating SDV platforms with multi-modal capabilities.”
The Role of Simulation and AI in Bridging the Divide
Ganapathi points to the simulation-first approach, enhanced by Generative AI, as a game-changer in enabling SDVs to operate across diverse traffic systems.
“These simulations allow virtual validation of scenarios across geographies, reducing dependence on physical prototypes and ensuring faster compliance with local laws,” he explains.
The solution lies in developing adaptive SDV software architectures that can seamlessly toggle configurations based on GPS location and local laws. “Additionally, global standardisation efforts for V2X protocols, while still nascent, must accelerate,” he urges.
Agrees, Prof. Chandan Chowdhury, Executive Director, Munjal Institute for Global Manufacturing, Indian School of Business (ISB), who adds, “Academia must adapt automotive curricula to address these dual standards, especially in control algorithms, digital twin simulations, and regional regulation modules.”
India, for instance, remains early in its V2X journey, highlighting the need for scalable, regionally compliant solutions. “Overall, a layered AI-driven system that accommodates geo-specific datasets will be central to ensuring safe and efficient cross-border SDV functionality. Ultimately, regulatory focus is shifting toward software flexibility and validation frameworks rather than altering age-old national systems.”
Legal Perspectives and Regulatory Focus
From a legal standpoint, a unilateral transition to a global traffic norm isn’t under consideration. “Regulators are not contemplating a switch in traffic orientation,” says Divyangna Malik, Advocate Supreme Court of India. “Instead, the legal focus globally is on fostering software modularity and harmonized regulatory standards to ensure interoperability of SDVs across both systems, primarily through platforms like UNECE WP.29 (United Nations Economic Commission for Europe).”
She notes that while no imminent legal transition is foreseen in drive-side norms, “strategic investments are being made to bridge localisation gaps for LHT countries within the SDV ecosystem.”
Highlighting the need for regulatory frameworks that can keep pace with the rapid evolution of automotive technologies, David Kidd, Senior Research Scientist at the Insurance Institute for Highway Safety (IIHS), says, “Every region is unique and requires a hyperlocalised approach in terms of safety, technology, and solutions.” He adds, “Driving cultures vary significantly across the world. To make SDVs truly successful, we need customised processes and algorithms that are optimised for local realities.” Kidd emphasizes on the need for flexibility and adaptability in SDV ecosystems, especially when addressing diverse cultural nuances, regulatory mandates, and behavioural patterns across geographies.
Adaptability Over Uniformity
In the context of SDVs, which depend on standardized, data-intensive software systems, the RHT-LHD model offers stronger logical and technological alignment. As the majority of SDV development, training data, and regulatory frameworks emerge from LHD markets, deployment is inherently more efficient in RHT jurisdictions.
However, true global scalability lies in adaptability and not in enforcing a singular norm. The future of autonomous mobility depends on intelligent, region-aware software systems, robust simulation tools, and cross-border standardisation efforts that bridge the left-right divide without forcing nations to rewrite the rules of their roads.
