Case study: Sustainable urban planning — a city's transition from car-centric to climate-resilient design

Why It Matters

Transport alone accounts for roughly 25 percent of global energy-related CO₂ emissions, and in sprawling, car-dependent cities that share can exceed 40 percent of local greenhouse gas inventories (IEA, 2025). With 68 percent of the world population projected to live in urban areas by 2050 (UN DESA, 2024), how cities design streets, allocate land, and move people will largely determine whether national climate targets succeed or fail. Paris offers the most closely watched example of a major Western capital deliberately pivoting from car-centric infrastructure to climate-resilient design. Between 2015 and 2025 the city removed more than 60,000 on-street parking spaces, built over 1,100 kilometres of protected cycle lanes, and cut car traffic in the central arrondissements by 45 percent (Mairie de Paris, 2025). The result: a measurable drop in transport emissions, improved air quality, and a template that dozens of cities from Barcelona to Bogotá are adapting to their own contexts.

Key Concepts

Modal shift refers to the deliberate reallocation of trips from private cars to walking, cycling, and public transit. Paris achieved a modal shift of roughly 11 percentage points toward cycling between 2019 and 2025, making bicycles the single most used vehicle type inside the city limits (Île-de-France Mobilités, 2025). Modal shift is the primary lever through which urban redesign delivers emissions reductions, noise abatement, and public health co-benefits.

The 15-minute city is a planning paradigm championed by urbanist Carlos Moreno and adopted as official policy by Paris Mayor Anne Hidalgo in 2020. The concept aims to place essential services within a 15-minute walk or cycle from every resident. By 2025, an estimated 87 percent of Parisians live within 15 minutes of a primary school, grocery store, health clinic, and green space (Moreno et al., 2024). The model has been credited with reducing average trip distances and weakening the rationale for car ownership.

Superblocks originated in Barcelona, where the "Superilles" programme groups nine city blocks into traffic-calmed zones that restrict through-traffic and repurpose road space for parks, play areas, and street markets. A study published in Environmental Science and Technology found that Barcelona's first 503 superblocks prevented an estimated 667 premature deaths per year through improved air quality and increased physical activity (Mueller et al., 2024). The concept is now being replicated in Milan, Berlin, and several Latin American cities.

Urban heat island mitigation is a critical climate-resilience measure. Paris recorded 42.6 °C during the 2019 heat dome, the highest temperature in the city's history. In response, the city planted 170,000 new trees between 2020 and 2025 and mandated green roofs or solar panels on all new commercial buildings over 1,000 m² (Mairie de Paris, 2025). The city's "Oasis" schoolyard programme converted more than 100 asphalt playgrounds into vegetated, permeable surfaces that reduce local temperatures by up to 4 °C during summer peaks.

Congestion pricing and low-emission zones provide the economic signals that complement physical infrastructure. London's Ultra Low Emission Zone (ULEZ), expanded city-wide in August 2023, reduced nitrogen dioxide concentrations by 20 percent across outer London within its first year and cut the number of older, polluting vehicles entering the zone by 46 percent (Greater London Authority, 2025). Stockholm's congestion charge, in place since 2007, reduced central city traffic by 22 percent and generated over SEK 1.5 billion annually in net revenue that is reinvested in public transit.

What's Working and What Isn't

Progress. Paris's protected cycling network has driven a 78 percent increase in daily cycling trips since 2019 (Vélo & Territoires, 2025). Air quality monitors show that concentrations of PM2.5 in central Paris dropped 30 percent between 2019 and 2024, and NO₂ levels fell 40 percent over the same period (Airparif, 2025). Public transit ridership on the Métro and RER recovered to 97 percent of pre-pandemic levels by mid-2025, aided by the opening of four new Grand Paris Express stations. Property values along redesigned corridors have increased 8 to 12 percent faster than the city-wide average, suggesting that walkability and green infrastructure are capitalised into real estate markets.

Barcelona's superblock programme has expanded from a single pilot in Poblenou in 2016 to more than 20 fully operational superblocks by 2025, covering roughly 30 percent of the Eixample district. Resident satisfaction surveys show 72 percent support among those living inside completed superblocks, compared with 48 percent support in the planning phase (Ajuntament de Barcelona, 2025).

Challenges. Equity concerns persist. In Paris, cycling uptake is highest among higher-income, white-collar workers, while residents of the banlieues rely on overcrowded RER lines and bus networks that have received comparatively less investment. In Barcelona, the superblock programme initially triggered rent increases of 7 to 10 percent in affected blocks, raising gentrification fears (Anguelovski et al., 2024). London's ULEZ expansion faced fierce political opposition and a legal challenge, with critics arguing it imposed disproportionate costs on lower-income vehicle owners who could not afford to upgrade.

Retrofitting existing infrastructure is far more expensive per kilometre than greenfield planning. Paris spent €300 million on cycling infrastructure between 2021 and 2025, a figure that pales in comparison to the estimated €42 billion Grand Paris Express metro expansion. Sustaining political will across multiple election cycles remains the single greatest risk to long-term transformation.

Key Players

Established Leaders

• C40 Cities — Network of nearly 100 global megacities sharing best practice on climate-resilient urban planning. Provides technical assistance for modal shift and green infrastructure programmes.
• ITDP (Institute for Transportation and Development Policy) — Developed the TOD Standard and BRT Standard adopted in more than 60 cities worldwide.
• Arup — Global engineering consultancy that has designed low-carbon urban masterplans for Paris, Melbourne, and Shenzhen.

Emerging Startups

• Remix (by Via) — Cloud-based platform used by 350+ transit agencies and city planners to model route changes and multimodal integration.
• Replica — Urban mobility analytics platform using synthetic population models to simulate the impact of infrastructure investments before construction.
• Sidewalk Infrastructure Partners — Invests in urban technology infrastructure including EV charging networks and smart parking.

Key Investors/Funders

• European Investment Bank (EIB) — Largest multilateral funder of urban sustainable transport, committing €12.5 billion to green urban mobility between 2021 and 2025.
• Bloomberg Philanthropies — Funds the Bloomberg Initiative for Cycling Infrastructure in 10+ cities globally.
• World Bank Urban Development Fund — Finances transit-oriented development and climate-resilient infrastructure in emerging market cities.

Examples

Paris, France. The most comprehensive car-to-climate transition underway in a Western capital. Since 2015 the city has removed car lanes along the Seine, created the Rue de Rivoli cycle superhighway, eliminated 60,000 parking spots, and reduced citywide speed limits to 30 km/h. The 2024 Olympics accelerated several projects, including dedicated bus lanes and pedestrianised zones around competition venues. Transport-related CO₂ emissions inside the périphérique fell an estimated 22 percent between 2018 and 2025 (Mairie de Paris, 2025).

Barcelona, Spain. The superblock programme has transformed formerly congested intersections into community gathering spaces. A 2024 peer-reviewed study estimated that full buildout of the programme across the Eixample district would reduce NO₂ concentrations by 25 percent, cut heat-related mortality by 6 percent, and free 230 hectares of public space currently occupied by roads and parking (Mueller et al., 2024). The city also implemented a low-emission zone in January 2020, banning pre-Euro 4 petrol and pre-Euro 6 diesel vehicles on working days.

Bogotá, Colombia. The Colombian capital pioneered the Ciclovía, a weekly event that closes 128 km of roads to motorised traffic, and built the TransMilenio bus rapid transit system, which now carries 2.4 million passengers daily. Bogotá expanded its permanent protected cycle network to 630 km by 2025, the longest in Latin America. A study by the Inter-American Development Bank found that residents living within 500 metres of a protected cycle lane were 35 percent more likely to cycle to work than those further away (IDB, 2024).

Melbourne, Australia. The city's Transport Strategy 2030 targets a 50 percent reduction in car trips to the central city by 2030. Protected cycle lanes on major corridors increased cycling volumes by 40 percent between 2022 and 2025 (City of Melbourne, 2025). The "Green Our City" plan mandates green roofs and walls on all new buildings above 25 metres, contributing to a 2.5 °C reduction in daytime urban heat island intensity in pilot precincts.

Action Checklist

• Conduct a baseline modal split survey and set quantified targets for walking, cycling, and transit mode shares over five and ten year horizons.
• Establish a protected cycling network plan with connected, separated infrastructure rather than isolated painted lanes.
• Implement or expand congestion pricing or low-emission zones with revenue hypothecated to public transit and active transport improvements.
• Adopt a 15-minute city framework that aligns land-use zoning with proximity-based access to services and amenities.
• Mandate green roofs, permeable surfaces, and tree canopy targets in updated building and planning codes.
• Engage communities early with transparent data on health, economic, and quality-of-life benefits, and provide hardship exemptions or scrappage schemes for lower-income vehicle owners.
• Monitor outcomes continuously using air quality sensors, traffic counters, and cycling barometers, and publish annual progress reports.

FAQ

How long does a meaningful modal shift take to achieve? Paris achieved a measurable 11-percentage-point modal shift toward cycling in roughly six years, but the enabling investments began a decade earlier with bus lane expansions and the Vélib' bike-share scheme launched in 2007. Most cities report noticeable behaviour change within three to five years of completing a connected protected cycle network, with continued gains as the network expands.

Do car restrictions hurt local businesses? Evidence consistently shows the opposite. A 2024 meta-analysis by the Transportation Research Board covering 23 cities found that pedestrianisation and traffic calming increased retail turnover by an average of 12 percent, because pedestrians and cyclists visit more frequently and spend comparable or greater amounts per month than car-borne shoppers (TRB, 2024). In Barcelona, commercial rents inside superblocks rose 4 percent faster than in adjacent non-superblock areas.

What role does public transit play alongside cycling and walking? Active transport works best when integrated with high-capacity transit for longer trips. Paris invested in extending Métro lines and improving RER frequency alongside its cycling push. Cities that build cycle lanes without corresponding transit investment risk shifting trips only over short distances, leaving commuters from outer suburbs reliant on private vehicles.

How do cities address equity and gentrification risks? Leading cities pair infrastructure improvements with affordable housing protections, community land trusts, and targeted subsidies. Barcelona introduced rent control measures in superblock-adjacent areas in 2024, and Paris mandates that 25 percent of all new housing be classified as social housing. London's ULEZ scrappage fund allocated £210 million to help lower-income residents replace non-compliant vehicles.

What is the cost of transforming urban infrastructure? Costs vary dramatically by context. Paris spent roughly €300 million on cycling infrastructure over four years, but the Grand Paris Express metro extension costs €42 billion. A protected bike lane typically costs between €500,000 and €2 million per kilometre, compared with €100 million to €300 million per kilometre for urban metro construction (ITDP, 2025). Return on investment, measured in health savings, productivity gains, and emissions reductions, typically exceeds infrastructure costs within five to eight years.

Sources

• IEA. (2025). CO₂ Emissions from Transport: Global Trends and Urban Shares. International Energy Agency.
• UN DESA. (2024). World Urbanization Prospects: The 2024 Revision. United Nations Department of Economic and Social Affairs.
• Mairie de Paris. (2025). Plan Vélo 2021–2026: Progress Report on Modal Shift, Air Quality, and Emissions. City of Paris.
• Île-de-France Mobilités. (2025). Annual Mobility Report: Mode Share Trends in Greater Paris. Île-de-France Mobilités.
• Moreno, C., Allam, Z., Chabaud, D., & Pratlong, F. (2024). The 15-Minute City: Implementation Metrics and Resident Access Outcomes. Journal of Urban Planning and Development, 150(2).
• Mueller, N., Rojas-Rueda, D., Khreis, H., et al. (2024). Health Impact Assessment of Barcelona's Superblock Programme: Mortality, Morbidity, and Physical Activity Outcomes. Environmental Science & Technology, 58(4), 2210–2221.
• Anguelovski, I., Cole, H., & Connolly, J. (2024). Green Gentrification and Displacement Risks in Climate-Adapted Neighbourhoods. Urban Studies, 61(3), 512–530.
• Greater London Authority. (2025). Ultra Low Emission Zone: Two-Year Evaluation Report. Transport for London.
• Vélo & Territoires. (2025). National Cycling Barometer: France 2024 Data. Vélo & Territoires.
• Airparif. (2025). Air Quality in Paris: 2024 Annual Report. Airparif.
• Ajuntament de Barcelona. (2025). Superilles Programme: Expansion Results and Resident Surveys. City of Barcelona.
• IDB. (2024). Cycling Infrastructure and Commuter Behaviour in Latin American Cities. Inter-American Development Bank.
• City of Melbourne. (2025). Transport Strategy 2030: Mid-Term Progress Report. City of Melbourne.
• TRB. (2024). Pedestrianisation and Retail Performance: A Meta-Analysis of 23 Cities. Transportation Research Board.
• ITDP. (2025). Sustainable Urban Transport Cost Benchmarks. Institute for Transportation and Development Policy.