Congestion Charging - Does it Work?

Urban centres across the globe grapple with an escalating challenge: traffic congestion. This pervasive issue extends beyond mere inconvenience, imposing significant economic costs through wasted fuel, delayed deliveries, and lost productivity.1 It also contributes substantially to air pollution and greenhouse gas emissions, impacting public health and accelerating climate change.1 In response, cities worldwide have explored various strategies, with congestion charging emerging as a prominent, market-based solution.

Understanding Congestion Charging: A Market-Based Solution

Congestion pricing, or congestion charging, is an economic strategy designed to alleviate traffic bottlenecks by imposing fees for the use of roads, particularly during peak travel periods.1 At its core, this approach treats road space as a scarce resource. When this resource is offered at a zero price, demand inevitably outstrips supply, leading to congestion. By introducing a price mechanism, congestion charging aims to allocate this limited resource to its most valuable uses, as reflected by drivers' willingness to pay.3

The fundamental purpose of congestion charging is multifaceted: to improve traffic flow, reduce environmental pollution, generate revenue for infrastructure investments, and incentivise alternative travel behaviours such as carpooling, public transport use, or off-peak travel.1 Various operational models exist, including:

• Cordon Pricing: A flat fee is charged for entering a designated area, often a city centre.1
• Area-Wide Pricing: Fees are applied for driving within a specified zone.1
• Dynamic Pricing: Tolls fluctuate based on real-time traffic conditions, allowing for more precise demand management.1

The continuous evolution from simpler, fixed cordon pricing to more sophisticated, real-time dynamic adjustments, as exemplified by Singapore's advancements towards GPS-based systems, signifies a broader trend in urban management. This progression indicates a commitment to increasingly precise, data-driven strategies for optimising resource allocation. Initial implementations often serve as foundational steps, paving the way for continuous refinement aimed at maximising efficiency and fairness in urban mobility systems.

This analysis delves into the experiences of five global cities – London, Stockholm, Singapore, Milan, and Gothenburg – to evaluate the effectiveness of congestion charging. It examines their motivations for implementation, the tangible impacts observed, the environmental benefits achieved, and the crucial lessons that can be drawn for future urban planning.

The Global Experiment: Cities Leading the Way

London: The Pioneer's Enduring Legacy

London's journey towards congestion charging began decades before its implementation, with the 1960s Smeed Report first assessing the practicality of road pricing.7 Despite early studies, public and political acceptance remained elusive until the late 1990s, when declining public transport performance and severe congestion in central London brought the idea back to the forefront.7 Inspired by Singapore's Electronic Road Pricing (ERP) system, the London Congestion Charge was eventually introduced on 17 February 2003.8 Its primary objectives were to reduce high traffic flow, mitigate air and noise pollution, and generate investment funds for the city's transport system.8

The impact on traffic has been significant. Transport for London (TfL) data revealed a 39% reduction in car traffic entering central London between 2002 and 2014.7 Overall traffic levels within the charging zone were consistently 16% lower in 2006 compared to pre-charge levels in 2002.8 Initial improvements in journey times were notable, with a 30% increase in 2004, though this declined to 7% by 2006 compared to the year before the scheme.8 TfL attributes this subsequent decline not to a failure of the charge, but to deliberate interventions aimed at improving the urban environment, enhancing road safety, and prioritising public transport, pedestrians, and cyclists.8 To support the shift, an additional 300 buses were introduced on the scheme's launch date 8, leading to bus patronage in central London increasing from under 90,000 to 116,000 journeys per day by 2007.8 Underground usage also saw a 1% increase above pre-charge levels by 2007.8

Environmental gains were initially reported by TfL, with Nitrogen Oxides (NOx) falling by 13.4%, airborne particulates (PM10) by 15.5%, and Carbon Dioxide (CO2) by 16.4% within the charging zone between 2002 and 2003.8 Further reductions were observed between 2003 and 2006, though the majority of these were attributed to improved vehicle technology rather than solely reduced traffic.8 This highlights a complexity in assessing the direct environmental impact of congestion charging. While it contributes to cleaner air by reducing vehicle numbers, its effectiveness can be influenced by other factors, such as vehicle fleet modernisation or the presence of exemptions. An independent 2011 study, for instance, found limited evidence that the congestion charge alone improved air quality, citing difficulties in isolating its impact from broader regional pollutant and weather changes.8 Furthermore, a 2020 study noted an increase in pollution from exempt diesel taxis and buses, indicating that exemptions can dilute the overall environmental benefit.8

Socio-economic impacts have been mixed. TfL estimated a neutral overall effect on businesses, but some reported significant losses in sales and increased delivery costs.8 Conversely, a study commissioned by London First found that 49% of businesses perceived the scheme as working.8 Concerns about social equity were raised, particularly regarding the flat daily charge disproportionately affecting lower-income individuals.8 However, a 2024 study suggested a progressive impact, benefiting low-skill commuters in the suburbs through reduced traffic.8 Public acceptance was initially fraught with fears of chaos and legal challenges.8 Despite a public consultation showing opposition to a proposed Western Extension, Mayor Ken Livingstone proceeded, famously stating, "A consultation is not a referendum".8 This demonstrates a crucial aspect of policy implementation: political determination and a clear vision can override initial public and business opposition, especially when the policy addresses a widely acknowledged problem like chronic congestion. The long history of considering road pricing, coupled with a strong political champion, allowed the policy to take root despite initial resistance.

Stockholm: A Referendum's Reversal

Stockholm's congestion tax, implemented permanently in August 2007 after a seven-month trial, aimed to reduce traffic congestion, improve the environment, increase accessibility, and fund new road constructions and metro extensions.11 The city's unique geography, with numerous congested bridges, made it a prime candidate for such a measure.12 Like London, Stockholm's system was inspired by Singapore's ERP.11

The trial period yielded immediate and visible results. Traffic decreased by 20% across the toll cordon, a reduction that has remained constant since permanent implementation.12 Congestion on arterial roads was reduced by 30-50%.12 These dramatic changes were widely reported in the media, showcasing almost empty streets during rush hours.12 Crucially, approximately half of the drivers who stopped entering the inner city switched to public transit.12 To accommodate this anticipated shift, Stockholm had expanded its public transit system, purchasing new buses and adding lines, prior to the trial.7

Environmentally, the scheme delivered tangible benefits. Emissions in the inner city decreased by 10-14%.12 More specifically, Nitrogen Dioxide (NO2) levels fell by 15-20%, and Particulate Matter (PM10) by 10-15%.13 This reduction in air pollution was notably associated with a 16% decrease in acute asthma attacks among young children during the trial period.13 This direct link between reduced emissions and improved public health, moving beyond abstract environmental metrics to tangible health outcomes, provided a powerful justification for the policy.

Initial public and political opposition to the Stockholm congestion tax was substantial; the Mayor had even campaigned against it, and one political leader famously called it "the most expensive way ever devised to commit political suicide".12 A referendum held after the trial period showed mixed results, with Stockholm municipality residents voting 53% in favour, while 14 other municipalities voted against.11 Despite this, political leaders proceeded with permanent implementation.11 Public support, however, dramatically increased once the trial began and the benefits became apparent, stabilising at around 70%.11 This experience vividly illustrates the transformative power of a well-executed pilot programme. Visible, immediate results can significantly shift public opinion from initial skepticism to strong support, often proving more persuasive than pre-implementation arguments or even initial referendum outcomes. The "reversal design," where the charge was introduced, temporarily abolished, and then reintroduced, further solidified the understanding of its positive impacts.12

Singapore: The Automated Trailblazer

Singapore stands as a global pioneer in congestion pricing, having introduced its Area Licensing Scheme (ALS) in 1975, which evolved into the automated Electronic Road Pricing (ERP) system in 1998.4 This initiative was driven by the city-state's limited land area, a rapidly growing car population, and the imperative for efficient road space utilisation.4 The primary objectives were to manage traffic flow, reduce congestion, and maintain optimal road speeds.4

The impact on traffic has been substantial. The ALS led to an immediate 45% traffic reduction and a 25% decline in vehicle crashes, with average travel speeds increasing significantly.14 The ERP system further decreased traffic by 15%.14 While these figures indicate clear success, one study suggested that ERP did not eliminate congestion entirely but rather shifted it in time and location, potentially increasing average travel time in some instances.5 This highlights a critical challenge: successful congestion pricing requires continuous monitoring and adaptive strategies to prevent displacement effects onto untolled roads or off-peak hours.

Singapore's success is inextricably linked to its heavy investment in public transport, which provides a viable and attractive alternative to driving.4 Currently, 65% of commuters use public transport, a nearly 20% increase attributed partly to the scheme.14 The ERP system also encourages car-pooling.5 Environmentally, ERP has contributed to a lowered environmental impact from vehicle emissions 4, with a reported 176,400-pound reduction in CO2 emissions within the charging zone.14 The city's air quality now meets health-based standards.14

Public acceptance, initially low, has generally improved over time.4 Singaporean officials proactively built public support by equipping 98% of vehicles with necessary electronic transponders free of charge and conducting extensive public education campaigns and demonstration periods.14 This proactive engagement helped familiarise drivers with the system and build confidence. Singapore's unique status as a small, densely populated city-state with strong political will and a highly centralised government has been a crucial factor in the effective and comprehensive implementation of ERP.4 This contrasts with larger, more fragmented governance structures, suggesting that the political and administrative context significantly influences the feasibility and success of such schemes. Unlike many other cities, Singapore's ERP revenues are directed into a general fund rather than being specifically earmarked for transport improvements.4

Milan: From Pollution Charge to Congestion Solution

Milan's Area C congestion charge, introduced in January 2012, replaced the earlier Ecopass pollution charge.15 The city faced severe traffic jams and some of Europe's highest car ownership rates, coupled with persistent air pollution problems.15 The preceding Ecopass, implemented in 2008, aimed to reduce polluting vehicles but became less effective at alleviating congestion as cleaner, exempt cars gained free access.15 This policy evolution demonstrates a crucial learning curve in urban management: policies must adapt to changing circumstances, such as advancements in vehicle technology, to maintain their intended impact on congestion, not just pollution. Area C's objectives were to drastically reduce chronic traffic jams, promote sustainable mobility and public transport, and mitigate dangerously unhealthy smog.15

Area C has achieved a significant and consistent reduction in daily vehicle entries into Milan's central zone. Immediately after its introduction in 2012, there was a 31.1% drop in entries compared to 2011.16 By April 2012, the traffic reduction within Area C was 34.3%, with a 7% reduction across the broader Milan area.15 This downward trend continued, resulting in a 38.45% reduction from 2011 to 2021.15 The reduced congestion also led to an increase in the average speed of public transport, particularly buses during peak hours, where speeds were approximately 10% higher than pre-Area C levels.15 All net revenues from the scheme are reinvested into promoting public transport and sustainable mobility, funding initiatives such as metro service increases and bike-sharing extensions.15

Environmental gains have been substantial. Area C has led to a significant decrease in air pollutants and a notable improvement in air quality.16 PM10 exhaust emissions decreased by approximately 87% between 2010 and 2021, and total PM10 emissions by about 60%.16 Nitrogen Oxides (NOx) plummeted by over 75%, and Carbon Dioxide (CO2) by 35%.16 The policy has also driven a significant shift towards cleaner Euro class vehicles and cleaner fuel types entering the zone.16

Public acceptance of Area C was initially met with considerable criticism, similar to its predecessor.15 Despite a 79% majority vote in a 2011 referendum favouring traffic limits and cleaner vehicles 17, the scheme faced protests and even legal challenges.15 Protests from car parking facility owners, who experienced reduced profits, led to a temporary suspension in 2012.15 The programme was also temporarily suspended during the COVID-19 pandemic to prevent public transport overcrowding, only to be reactivated later due to rising pollution levels.15 Milan's experience highlights the inherent tension between different policy objectives and the conflicting interests of various stakeholders. The temporary suspensions underscore the political vulnerability of such schemes to public pressure and unforeseen events, emphasising the need for robust political backing and clear communication of benefits.

Gothenburg: Sweden's Smaller City Success

The Gothenburg congestion tax, introduced on 1 January 2013, was modelled after Stockholm's successful system.19 Its core purposes were to reduce traffic congestion, improve the environmental situation in central Gothenburg, and provide financing for major road and rail construction projects, such as the West Link railway line.19 Gothenburg presents a unique case study as it is a smaller city than Stockholm, with lower initial congestion levels and a smaller public transport market share.20 Its success broadens the applicability of congestion charging beyond mega-cities, suggesting its viability across a range of urban scales and existing transport conditions.

In its first year, the total traffic volume across the affected area during charged hours decreased by approximately 10%.19 Inner-city streets specifically saw a 9% reduction during charged hours.19 However, some circumferential roads experienced increased traffic, indicating that drivers altered their routes to avoid tolls, a common challenge that requires continuous monitoring.19 Public transport trips for affected routes increased by 9% in the initial months following implementation.19

Environmentally, the congestion tax has contributed to improving the air quality in central Gothenburg.19 Studies found that NO2 emissions were reduced by 6.3% and PM10 by 11%.22 A comparative study further associated the congestion tax with reductions of up to 17-19% in NOX and PM10 levels in Gothenburg compared to Malmö, a control city without the tax.24

Socio-economically, the tax provides crucial financing for large road and rail construction projects, contributing approximately half of the necessary funding for infrastructure development.19 However, studies indicate the system is weakly regressive.20 The ability for company car users, who often have higher incomes, to deduct the charge implies negative equity effects.20 Public acceptance was initially low, with a consultative referendum in 2014 showing 57% voting against the charge.20 Nevertheless, the newly elected city council opted to disregard the referendum result and maintain the charges.20 Support for the charge did increase after its introduction.20 This case starkly highlights a scenario where strong political will, influenced by institutional settings and control over revenues, can override a negative public referendum result, demonstrating that the mechanism of policy adoption can be as crucial as public sentiment itself.

The Verdict: Does Congestion Charging Work?

The evidence from London, Stockholm, Singapore, Milan, and Gothenburg overwhelmingly suggests that congestion charging, when implemented thoughtfully, can be an effective tool for urban management.

Common Threads of Effectiveness:

• Traffic Reduction: All five cities demonstrably reduced traffic volumes within their charged zones, with reductions ranging from 10% in Gothenburg to 39% in London (2002-2014 data) and 45% in Singapore (ALS).7 This directly addresses the primary objective of alleviating road crowding and improving traffic flow.1
• Environmental Benefits: Tangible improvements in air quality were reported across all cities, with significant reductions in key pollutants such as PM10, NOx, and CO2.1 Stockholm's experience even linked these reductions to improved public health, specifically a decrease in childhood asthma attacks.13
• Revenue Generation and Reinvestment: These schemes consistently generate substantial revenue, which is often strategically reinvested into public transport infrastructure, fostering a virtuous cycle that further supports sustainable mobility.1
• Encouraging Behavioural Change: By pricing road use, these schemes incentivise shifts to public transport, carpooling, cycling, or off-peak travel, fostering long-term changes in urban mobility patterns.1

The success of congestion charging is not merely about reducing traffic in isolation; it initiates a cascade of interconnected benefits. Traffic reduction directly leads to environmental improvements, which can then translate into public health benefits. The revenue generated from the charge, when reinvested into public transport, reinforces the shift away from private car use, creating a self-sustaining positive feedback loop for urban sustainability.

Persistent Challenges:

Despite these successes, several hurdles persist:

• Public Acceptance: Initial public and political opposition is almost universal.4 While acceptance often grows after visible benefits emerge, it can remain fragile and subject to political shifts or external events, as seen with Milan's COVID-19 suspension.15
• Equity Concerns: The flat daily charge can disproportionately affect lower-income individuals or essential workers, raising fairness concerns.4 While some studies indicate progressive impacts 8, the regressive nature remains a recurring critique, particularly evident in Gothenburg.20
• Traffic Displacement: Congestion may not be eliminated but merely shifted to untolled roads or off-peak hours, necessitating careful monitoring and adaptive strategies.5
• Ongoing Congestion: Even with charges, congestion can persist or rebound due to other urban planning interventions, such as repurposing road space for pedestrians, or general traffic growth.8

The consistent pattern of initial political and public resistance, often followed by increased acceptance once benefits are realised, suggests a "political courage" paradox. Implementing such a policy often requires significant political determination to push through an initially unpopular measure, trusting that its eventual success will justify the initial backlash.

Table 1: Congestion Charging at a Glance: Key Metrics Across Five Cities

Lessons for the Road Ahead: Paving the Way for Future Implementations

The global experience with congestion charging offers invaluable insights for cities considering or refining such policies:

• The Crucial Role of Public Transport Alternatives: The availability of reliable, accessible, and affordable public transport is not merely a desirable outcome but an essential enabling condition for successful congestion charging.1 Without viable alternatives, tolls are likely to be perceived as punitive rather than beneficial.1 Cities like Stockholm proactively expanded their public transit systems before implementing the charge, demonstrating that robust alternatives reduce the burden on drivers and enhance the policy's acceptability and effectiveness.7 Investment in expanding public transport networks is thus a prerequisite and often a direct outcome of congestion charging revenues.5
• Strategic Revenue Reinvestment: Earmarking revenues specifically for transport infrastructure improvements, such as metro extensions or bus network upgrades, is crucial for gaining and maintaining public support.2 This ensures that the programme is perceived as a collective investment in a better transport system, rather than simply an additional tax.28 The Gothenburg case, where public support was low partly because the real reason for the charge (revenue for projects with low social returns) was perceived, underscores the importance of transparently communicating how funds are utilised.27 When citizens observe direct benefits from the funds collected, it transforms the perception of the charge from a burden to a shared investment in urban improvement.
• Transparent Communication and Public Engagement: Initial public resistance often stems from fear of the unknown or perceived unfairness. Transparent communication about the purpose, benefits, and operational details is critical for public understanding and support.1 Pilot programmes, as seen in Stockholm, and comprehensive public education campaigns, as implemented in Singapore, can be highly effective in demonstrating tangible benefits and building public confidence.12 This approach helps bridge the perception gap by allowing citizens to experience the advantages firsthand, thereby fostering acceptance. Direct experience of reduced congestion and improved travel times often proves more persuasive than theoretical arguments or pre-implementation forecasts.
• Addressing Equity and Socio-economic Impacts: While congestion charging is economically efficient, its social acceptability hinges on addressing equity concerns. Careful consideration of the distributional effects, particularly on lower-income individuals and essential workers, is essential.4 Policies that fail to mitigate the disproportionate impact on vulnerable groups risk significant public backlash and undermine long-term success. Mechanisms such as discounts for residents, exemptions for certain vehicle types (e.g., disabled, taxis), or transit subsidies can effectively alleviate negative impacts.4 Milan's resident discounts and Stockholm's finding that lower-income individuals benefited from lower transit fares illustrate that proactive measures can address these concerns, requiring a holistic approach that balances economic efficiency with social justice.
• Leveraging Technology and Adaptive Pricing: Efficient toll collection systems, utilising electronic tags, cameras, and Automatic Number Plate Recognition (ANPR), are vital for minimising disruption and ensuring seamless operation.1 The evolution towards dynamic pricing models, which adjust charges based on real-time traffic conditions, offers greater flexibility and effectiveness in targeting congestion hotspots.1 Continuous monitoring and evaluation are necessary to adapt pricing structures and zone boundaries to changing traffic patterns, such as the shifting of congestion to untolled roads or off-peak hours.2 This iterative approach allows cities to refine their schemes for maximum effectiveness and efficiency over time, moving beyond static policy implementation to continuous, data-driven optimisation.
• Political Will and Long-Term Vision: The recurring theme of political courage overriding short-term public unpopularity, evident in London, Stockholm, and Gothenburg, suggests that congestion charging is not merely a transport policy but a significant urban transformation initiative.7 Its success often depends on political leaders' willingness to commit to a long-term vision, even in the face of immediate opposition, understanding that the systemic benefits outweigh the initial political cost. The ability to frame the charge as a long-term solution for urban sustainability and quality of life, rather than just a tax, is crucial for fostering broader acceptance.1 This implies that the policy's implementation is as much about political strategy and leadership as it is about economic rationale or technical feasibility.

Conclusion: A Path Towards Sustainable Urban Mobility

The global experience with congestion charging demonstrates its significant potential as a vital tool for managing urban traffic, reducing pollution, and generating revenue for public transport improvements. While challenges persist, particularly concerning initial public acceptance, equity, and the potential for traffic displacement, the case studies of London, Stockholm, Singapore, Milan, and Gothenburg provide compelling evidence that these schemes can work effectively.

Success hinges on thoughtful implementation, underpinned by a robust public transport network, strategic reinvestment of revenues, transparent communication, proactive addressing of equity concerns, and continuous adaptation through technological advancements. Ultimately, the political will to commit to a long-term vision for urban sustainability, even in the face of immediate opposition, is paramount. By embracing these lessons, cities worldwide can pave the way for more livable, sustainable, and economically vibrant urban environments for generations to come.

References

1. Understanding Congestion Pricing: What It Is, When It Works, and Its Purpose, accessed on May 29, 2025, https://frontlineadvisorygroup.com/understanding-congestion-pricing-what-it-is-when-it-works-and-its-purpose/
2. Can Congestion Pricing Help Solve Urban Traffic Problems? - Econofact, accessed on May 29, 2025, https://econofact.org/can-congestion-pricing-help-solve-urban-traffic-problems
3. Congestion pricing - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/Congestion_pricing
4. Made In Singapore: ERP, the traffic solution pioneered by the ..., accessed on May 29, 2025, https://www.straitstimes.com/life/made-in-singapore-erp-and-the-polarising-traffic-solution-pioneered-by-the-republic
5. Electronic Road Pricing - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/Electronic_Road_Pricing
6. Singapore's Innovative Approach to Traffic Management and Pollution Control - RP World, accessed on May 29, 2025, https://econ.sites.northeastern.edu/wiki/microeconomics/markets-and-government/singapores-innovative-approach-to-traffic-management-and-pollution-control/
7. www.sfcta.org, accessed on May 29, 2025, https://www.sfcta.org/sites/default/files/2020-02/Congestion-Pricing-Case-Studies_2020-02-13.pdf
8. London congestion charge - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/London_congestion_charge
9. The London Congestion Charge - American Economic Association, accessed on May 29, 2025, https://pubs.aeaweb.org/doi/10.1257/jep.20.4.157
10. London's congestion charge and its low emission zones - OECD, accessed on May 29, 2025, https://www.oecd.org/en/publications/ipac-policies-in-practice_22632907-en/london-s-congestion-charge-and-its-low-emission-zones_c6cd48e9-en.html
11. Stockholm congestion tax - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/Stockholm_congestion_tax
12. Stockholm Congestion Pricing - Tools of Change, accessed on May 29, 2025, https://toolsofchange.com/en/case-studies/detail/670
13. Congestion Pricing, Air Pollution and Children's Health - National Bureau of Economic Research, accessed on May 29, 2025, https://www.nber.org/system/files/working_papers/w24410/w24410.pdf
14. Singapore: A pioneer in taming traffic - Environmental Defense Fund, accessed on May 29, 2025, https://www.edf.org/sites/default/files/6116_SingaporeTraffic_Factsheet.pdf
15. Milan Area C - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/Milan_Area_C
16. Milan's Area C Statistics – Impact on Traffic & Polution - Area C Milano, accessed on May 29, 2025, https://www.areacmilano.it/en/milan-area-c-statistics-iImpact-traffic-polution.html
17. Effectiveness and Monetary Impact of Milan's Road Charge, One Year After Implementation, accessed on May 29, 2025, https://www.researchgate.net/publication/282449843_Effectiveness_and_Monetary_Impact_of_Milan's_Road_Charge_One_Year_After_Implementation
18. Milan's Area C reduces traffic pollution and transforms the city center, accessed on May 29, 2025, https://www.c40.org/case-studies/milan-s-area-c-reduces-traffic-pollution-and-transforms-the-city-center/
19. Gothenburg congestion tax - Wikipedia, accessed on May 29, 2025, https://en.wikipedia.org/wiki/Gothenburg_congestion_tax
20. The Gothenburg Congestion charges: CBA and equity - Trafikverket, accessed on May 29, 2025, https://fudinfo.trafikverket.se/fudinfoexternwebb/Publikationer/Publikationer_003001_003100/Publikation_003042/gbg%20cba%20v09.pdf
21. Congestion tax in Gothenburg - Transportstyrelsen, accessed on May 29, 2025, https://www.transportstyrelsen.se/en/road/vehicles/taxes-and-fees/road-tolls/congestion-taxes-in-stockholm-and-gothenburg/congestion-tax-in-gothenburg/
22. The Gothenburg congestion charge. Effects, design and politics - ResearchGate, accessed on May 29, 2025, https://www.researchgate.net/publication/275060309_The_Gothenburg_congestion_charge_Effects_design_and_politics
23. Congestion Charging Model in Sweden - WSP, accessed on May 29, 2025, https://www.wsp.com/en-gl/projects/congestion-charging-model-in-sweden
24. The Gothenburg congestion tax and air quality - GUPEA, accessed on May 29, 2025, https://gupea.ub.gu.se/bitstream/handle/2077/61946/gupea_2077_61946_1.pdf?sequence=1&isAllowed=y
25. The Gothenburg congestion tax and air quality-A difference-in-difference analysis - GUPEA, accessed on May 29, 2025, https://gupea.ub.gu.se/handle/2077/61946
26. Who Pays Congestion Charges?, accessed on May 29, 2025, https://www.wu.ac.at/fileadmin/wu/s/MANDANT_X_-_NUR_F%C3%9CR_KURSE/Assets/Who_congestion_charge.pdf
27. The Gothenburg congestion charge. Effects, design and politics, accessed on May 29, 2025, https://fudinfo.trafikverket.se/fudinfoexternwebb/Publikationer/Publikationer_002901_003000/Publikation_002940/B%C3%B6rjesson%20Kristoffersson%202015.pdf
28. Why The Battle Over NYC's Congestion Charge Matters To The Future Of Work, accessed on May 29, 2025, https://allwork.space/2025/03/why-the-battle-over-nycs-congestion-charge-matters-to-the-future-of-work/