Why Modern Cities Are Embracing Trolleybuses Again

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The humble trolleybus is enjoying an unexpected global revival, quietly returning to the spotlight in the relentless push for sustainable urban transit solutions. Once dismissed as obsolete or nostalgic, the trolley bus — now dramatically transformed by modern In-Motion Charging (IMC) technology — is proving to be a strategic and economically attractive option for cities seeking to rapidly decarbonize their transit networks.

Trolleybus systems experienced significant growth during the 20th century, with over 800 systems established worldwide at their peak. These electric buses, powered by overhead wires, were favored for their efficiency and lower emissions compared to diesel buses. However, the latter half of the century saw a decline in their usage, particularly in Western countries, due to the rise of private automobiles and the flexibility offered by diesel buses. In the mid-20th century, major U.S. automotive manufacturers, notably General Motors, deliberately acquired and dismantled trolley and streetcar systems across numerous American cities to promote car ownership and diesel buses, significantly accelerating the decline of electric urban transit.

Despite this, trolleybuses have maintained a presence in many cities, especially in Eastern Europe and parts of Asia. As of recent data, approximately 300 trolleybus systems are still in operation globally, reflecting a renewed interest in sustainable and electric public transportation options.

Far from being a simple throwback to mid-20th-century infrastructure, today’s trolleybuses leverage advanced battery systems and smart overhead management, fundamentally changing the calculus of urban electrification. And they come with all the mod-cons, including wifi, device charging, and climate control, making passengers much happier than legacy trolley systems.

IMC trolleybuses represent a substantial leap forward from their predecessors. Traditional trolleybuses were rigidly confined to routes beneath continuous overhead wires. Modern IMC-equipped models now incorporate onboard batteries capable of powering the vehicles off-wire for substantial distances, typically covering 10% to 30% of their routes independently. This off-wire capability addresses one of the trolleybus’ historical limitations, allowing for route flexibility around obstructions, reducing visual clutter in sensitive urban areas, and dramatically simplifying infrastructure installation. Additionally, modern trolleybuses harness regenerative braking, capturing kinetic energy during deceleration and returning it to either onboard storage or back to the grid, boosting overall energy efficiency.

These technological advancements are more than theoretical. A host of global cities are actively reintroducing or significantly expanding trolleybus systems, each driven by a compelling mixture of economic, environmental, and operational rationales. Tallinn, the capital of Estonia, exemplifies this pragmatic renaissance. After initially planning to completely eliminate its aging trolleybus network in favor of diesel or battery-electric alternatives, Tallinn reversed course in 2024 upon re-examining lifecycle economics and emissions targets. By committing to procure 40 new IMC-equipped trolleybuses, the city calculated significant cost advantages by leveraging its existing infrastructure and avoiding the expenses and downtime associated with large-scale battery bus charging operations.

Similarly, the French city of Nancy offers a cautionary and instructive tale of urban transit innovation. In 2000, Nancy replaced its traditional trolleybuses with an experimental guided-bus system called TVR, which proved unreliable and costly over two decades. After finally scrapping the TVR in 2023, Nancy returned to trolleybus technology, deploying bi-articulated IMC trolleybuses on its busiest urban corridors. This return was not nostalgic but rather pragmatic, leveraging partial re-use of existing overhead wiring while employing off-wire battery operation to maintain aesthetics in the historic city center. Early public feedback in Nancy has been strongly positive, citing improved reliability, comfort, and environmental performance.

Prague, capital of Czechia, provides another instructive example, reviving trolleybuses in 2023 after a 50-year hiatus. Facing a challenging airport corridor with steep grades and heavy passenger loads, Prague evaluated several transit options, including battery-electric buses and trams. The city ultimately chose IMC trolleybuses, deploying large, double-articulated models from Škoda-Solaris on the route, combining overhead wiring with battery segments to balance infrastructure investment and operational flexibility. This pragmatic deployment significantly increased route capacity and reliability, underscoring the trolleybus’ suitability for demanding urban transit environments.

In Italy, multiple medium-sized cities have quietly become pioneers of modern trolleybus deployment. Avellino, in southern Italy, reintroduced trolleybuses in 2023 after nearly 50 years of absence, capitalizing on European Union green mobility funding. Branding its new trolleybus line as a “Metro Leggera” (light metro), the city emphasized its clean and quiet operation, successfully overcoming political skepticism. Nearby Lecce similarly introduced a completely new trolleybus network, carefully designed to preserve its heritage streetscape, demonstrating that modern IMC trolleybuses can coexist harmoniously with historical urban fabric. Meanwhile, Pescara is actively developing an ambitious trolleybus-based Bus Rapid Transit (BRT) line along the Adriatic coast, signaling growing national confidence in the trolleybus as a high-capacity urban transit solution.

Across the Atlantic, Mexico City’s recent trolleybus resurgence is arguably one of the most striking global examples. Rather than starting anew, Mexico City opted to dramatically modernize its extensive legacy trolley network, acquiring hundreds of new IMC-capable vehicles to retire its aging fleet. In 2021, it opened a pioneering elevated trolleybus BRT line, achieving impressive ridership and emission reductions. This innovative approach demonstrated that existing trolleybus systems could not only be revitalized but substantially expanded, improving urban mobility and air quality without the need for extensive charging infrastructure typical of large battery-electric fleets.

Not all stories of trolleybus reintroduction have proceeded smoothly. Marrakesh in Morocco ambitiously launched Africa’s first trolleybus-based BRT system in 2017. Initial operations were promising, attracting significant ridership and attention. However, the system experienced a significant operational failure in 2022 when a truck damaged part of the overhead wire network, revealing that the city lacked adequate technical expertise and spare parts to quickly manage repairs. The line remained inactive for several months, demonstrating the critical need for robust institutional capacity and technical readiness when adopting advanced infrastructure technologies. Marrakesh’s experience, though cautionary, does not diminish the potential utility of trolleybuses, but rather underscores the importance of proper preparation and maintenance capacity.

Unsurprisingly, China has some of the biggest trolleybus systems in the world. Beijing operates one of the world’s most extensive and technologically advanced trolleybus networks, a system that has evolved significantly since its inception in 1957. Today, the network encompasses 31 routes, serviced by a fleet of over 1,250 dual-mode trolleybuses capable of operating both on overhead electric lines and on battery power. The system includes three high-volume bus rapid transit lines, a common intersecting pattern.

Beyond individual city examples, trolleybuses stand out in comparative analysis with other bus technologies, particularly on high-demand urban corridors. Their continuous power supply from overhead wires means they can handle steep hills and sustained high-frequency operations better than battery-electric buses, which face range limitations and downtime for recharging. Furthermore, trolleybuses typically demonstrate higher overall energy efficiency, not burdened by the battery packs as heavy as those in stand-alone battery-electric buses. Lifecycle cost analyses in cities such as Seattle and Tallinn have consistently shown trolleybuses to offer competitive total ownership costs, particularly when considering their longer vehicle lifespans and lower energy consumption per kilometer.

Trolleybuses are also exceptionally well-suited to dense urban environments where installing extensive battery charging infrastructure would be difficult or disruptive. They excel on routes with intensive usage, providing near-continuous service without interruption for charging. Importantly, trolleybuses represent a robust energy resilience strategy, leveraging existing electrical infrastructure and enabling straightforward integration with renewable power sources, substantially contributing to urban emission reduction targets.

Looking ahead, trolleybuses appear set to retain and possibly expand their role as a strategic element of urban electrification. Their adoption trajectory is likely to vary geographically — strong in Europe, selective yet significant in Asia and Latin America, and potentially emergent in Africa, provided technical and institutional capacities are adequately addressed. Trolleybuses will probably coexist synergistically alongside other electric bus technologies rather than replacing them outright, complementing battery-electric buses on lower-demand routes while often managing the high-capacity, high-frequency urban corridors where their continuous power delivery and energy efficiency shine brightest.

The global resurgence of trolleybuses, thus, is not merely a return to an older transit mode. Instead, it represents cities thoughtfully recalibrating their electrification strategies, choosing pragmatic solutions that blend proven reliability, improved flexibility, economic prudence, and environmental responsibility. As urban areas worldwide strive toward sustainability, trolleybuses offer not nostalgic novelty but rather a tested, sophisticated, and quietly effective tool to accelerate the transition to clean transit.