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Congestion Charging Q&A

1. What is " congestion charging"?

Congestion charging means charging cars on some specific roads and at some specific periods in order to regulate the traffic flow in time and space and lower the traffic burden on rush roads during rush hours. It is aimed at mitigating congestion and improving urban traffic efficiency. Congestion charging is a sur-charge to drivers for the use of congested roads, which aims at regulating travel demands and mitigating congestion without increasing the supply of infrastructure. London, Singapore, Stockholm and Milan are good examples in implementing congestion charging.

2. Is Congestion charging a fair method? Will it add on to the burden of middle-class car owners?

It is fair to use congestion charging. In a single trip, some parts of the cost will be paid by the traveler his/herself, while other parts will be paid by the society. If in a journey, the traveler pays $1 and the society will pay $0.01 for a pedestrian, $0.08 for a cyclist, $1.5 for a bus passenger and $9.2 for a car driver. The society has to pay for the expensive cost of emissions, traffic accidents, road infrastructure, noise as well as congestion. To the society as a whole, the price of cars is a lot higher than other green transport methods. Therefore, it is unfair to other environmental-friendly traveler if congestion charging is not implemented.

In fact, when this policy is conducted in foreign cities, the fairness problem is always taken into consideration by the governments. Taking London for example, the person who drives to downtown London is usually rich, while the majority of low-income people will use public transportation instead. Besides, when deciding the types of vehicles qualified for exemption, the interests of different groups have been considered and many types including taxis are included. Besides, private owned cars registered in charging areas can enjoy a "discount" policy. Meanwhile, revenue generated from congestion charging is used in developing urban transportation, especially public transportation, which also illustrates it is a fair policy.


Finally, the use and distribution of revenue is of vital important to the successful implementation. It should be used on improving transportation system and benefiting common residents. Meanwhile, the use of the revenue should be published so that people can get and realize the benefits from congestion charging.

3. In China, will the congestion really be mitigated through congestion charging?


In London, since congestion charging policy came into power, the mode split of private owned cars has dropped from 41% in 2003 to 32% in 2016, therefore, this policy is treated as a very efficient policy. " One thing we underestimated when we introduced congestion charge, was the number of people that would stop using their cars. Twice as many as we expected." explained the former mayor Ken Livingstone. Recent years, though congestion in London is still a problem, it was due to the increased activity and availability of for-hire services, like Uber, and the growth of delivery vans from booming e-commerce services. Street closings for pedestrian areas, sidewalk expansions and implementation of protected bike lanes have also reduced space for cars. These measures reallocate more road space to pedestrians and cyclist and decrease the space enjoyed by motorized vehicle.

However, experience cannot be implemented in China directly without any changes. When choosing the approach to implement the policy, not all advanced methods should be adopted. Only after examining and comparing different technology systems and considering local environment, should a method be chosen. Besides, it is worth to notice that, congestion charging should not be implemented alone, to fulfill the goals of the policy, a series of policies should be put into use together.

4. What policies should be launched along with congestion charging?


It is clear that congestion charging policy cannot work out perfectly on itself. The policy should not be implemented alone but should become one import part in the whole congestion mitigation policies set. Its design cannot exist alone without the company of congestion mitigation and environment improvement measures. The corresponding supporting designs need to be carried out together with the design of other congestion mitigation and emission reduction policies to provide more choices for travelers. For example, when congestion charging in London came into power, a series of policies in traffic areas were also put into use to ensure the effectiveness of the policy, including improving public transportation service, providing detour schemes, optimizing signal timing and ensuring parking for residents around the charging area. When congestion charging is implemented in China, some policies should also be considered at the same time, naming establishing an intelligent traffic management system; improving public transport services for charged areas; adjusting parking lots and parking transfer system layouts; organizing commercial facilities traffic; rationally using and allocating funds to improve social welfare; formulating public awareness policies.

5. What is the principles when design congestion charging policy?


When design congestion charging policy, the six principles below can be followed.

  1. Principle of fairness and rationality. Transport should meet the travel demand of all citizens and must reflect the principle of fairness. It should not only improve mobility for the minority of people, but also provide commuting service for all the citizens, especially ordinary employees and students. The fast speed and comfort of cars should not be pursued at the expense of the pedestrian, bicycling and public transit facilities of ordinary citizens. 

  2. Principle of economic and environmental sustainability: Urban transport is an important condition for sustainable urban economic and social development. TDM should not be introduced at the price of containing social and economic development, and transport improvement should not be achieved at the expense of environmental deterioration. Instead, sustainable environmental and economic development should go hand in hand with transport improvement. 

  3. Principle of public transit priority. In some sense, transport facilities are also a kind of product, which should be paid for use and reflect the principle of exchange at equal values. Too low charge on individual transport mode that occupies much land resources and urban space will lead to excessive user population, lower overall benefits, inadequate supply of road facilities and ultimately traffic congestion. Public transport service that occupy less space and resources should have be comfortable and fast, with proper pricing and government subsidies when necessary so that the overall benefits of urban transport system will be enhanced and the need of social and economic development and public mobility will be met. Using economic leverage can improve urban transport structure and fully release the potential of road facilities.

  4. Principle of balanced utilization of road resources. Existing road time and space resources should be fully utilized through TDM so that road network will be efficiently utilized both in terms of time and space. In that way, traffic flow will be evenly distributed in the urban road network and congestion caused by excessive traffic concentration will be minimized. 

  5. Principle of combining various measures and promoting coordinated development. Macro and micro TDM policy, measures and programs should be combined together. Overall travel demand strategic program should be drafted based on macro analysis and specific effective measures should be adopted by combining and coordinating macro strategic guidance and micro analysis. TDM for dynamic transport and static transport should also be combined and coordinated and equal emphasis should be placed on both of them.

  6. Principle of applying measures according to local conditions. TDM policy measures involve a wide range of aspects and their success hinges upon the understanding, trust and support of various related agencies and users in particular. The precondition of success is the willingness of the public to accept the measures.

6. What are the key factors in successful implementation of congestion charging policy?


Based on the experiences of London, Singapore and Stockholm, we conclude that the following factors in national and municipal government are key factors in successful implementation of congestion mitigation and emission control policies.


National Government

  • Legal Safeguard: the national government should combine the objectives of local congestion charging schemes with national transportation strategies in a clear and consistent manner. National government should also support the implementation of local congestion mitigation and emissions reduction policies through favorable legislation, regulation, and policies.


Municipal Government

  • Strong Policy Objectives: the municipal government should set clear and strong objectives before implementing the congestion charging scheme. Strong objectives are the starting point for developing an effective scheme, and can help to ensure consistency throughout policy preparation, implementation, operation, management, and monitoring. Consensus on objectives and the implementation process should be reached early, because multiple local government agencies will be involved during policy development and enforcement.

  • Comprehensive Feasibility Study: local government should conduct comprehensive studies focusing on implementation details, such as charging fees and targets. Modeling and scientific analyses are important to evaluate different scenarios and provide support to decision-making.

  • Equity and Transparency in Policy Implementation: the allocation of revenues from congestion charging is critical to policy implementation outcomes. We recommend that revenues be dedicated to transportation system improvements, and that the process be transparent, which helps to increase policy acceptability among the public.

  • Reliable Technologies: innovative and advanced technologies are not necessarily the right choice when selecting technological systems. Field-proven technologies that are appropriate to local circumstances offer the greatest chance of successful implementation.

  • Effective Public Communication: Public communication is one of the key elements in ensuring policy acceptability. Communication strategies should be effective, and updated to take account of public feedback and enable public communication to serve its purpose of improving policy acceptability.

  • Sound Complementary Measurements: The congestion charging scheme should be considered as an effort to improve transportation and the environment. A complete set of complementary measurements that offer viable alternative travel options and mitigate potentially unwelcome impacts of the scheme should be developed before implementation.

7. What are the key factors in designing congestion charging policy?


Policy Goal

Congestion charging policy is aimed at alleviating traffic congestion in targeted areas and improving traffic efficiency. City authorities may choose various indicators to measure congestion according to local conditions. 

Charging for congestion can improve travel efficiency, shorten the automobile engine idling time and help reduce the greenhouse gas and pollutant emission. However, the reduction of pollutant emissions should not be the primary goal for congestion charging policy.


Charging Methods

Based on local traffic characteristics, the present technology allows city authorities to choose suitable charging methods from charging by regions, charging in key road sections, charging by distance.


Charging Vehicles

The congestion charging policy shall follow the “Users Pay Principle” and be adapted to local traffic conditions. Generally speaking, payers are mainly vehicle users that consume more space and time resources per person and generate higher unit congestion external cost, such as private cars, light vans and taxis, and, in some cities, motorcycles and electronic bicycles.

The partial or complete exemption may directly impact on the operation efficiency of congestion charging policy, unit charging price and total income. Besides, it can guide citizens’ traveling behaviors. Therefore, the design of partial or complete exemption is significant in the implementation of the policy and can follow the principles:

  1. Avoid preferential fee or exemption as possible.

  2. No exemption should be granted if preferential charging works.

  3. Citizens’ choice of transportation vehicles can be guided by preferential policies.


Basically, exemption is applied to buses, utility vehicles, ambulance and emergency rescue vehicles, police cars and vehicles used by the disabled. Preferential toll should mainly be applied to residents living in toll regions and other special users of transportation vehicles. After the implementation of policy, the range of payer can also be adjusted to traffic conditions. 


Charging Areas

Congestion pricing policy should be implemented in areas with high land-use intensity, high traffic occupancy intensity or in regions with rare ecological landscape resources. These regions normally have the most congested traffic, mainly in the central area of a city. In these regions, it is hard to build new roads because of highly concentrated social economic activities, high road load and limited land resources. Therefore, traffic congestion in these regions has existed for years and is stillworsening. Fees can also be collected in major traffic corridors, fast road system or congested sections of expressways.  


Operation Hours

Congestion charging should be time specific, aimed at reducing peak hour traffic, and therefore its day and time period should be determined by features of traffic congestion in a city. 

Operation hours are normally morning and evening rush hours, and sometimes extended to a whole workday, holidays and other time span when congestion may occur.

It should be noted that operation hours could be adjusted to arise less objections by business and residents in the charging areas, so as to maintain and consolidate business advantages in the target area.


Charging Fees

The charging fees in different cities is subject to multiple factors such as external cost quantification of congestion, traffic volume, resilience of demand for traffic, economic development level and the environmental impact. 

External cost of congestion is the basis for the charging fees formulation and is mainly composed of additional commuting time and cost of traffic accidents. Notably, pollutant is also part of external cost of congestion. Low emission area designation and congestion charging can help together provide incentives to update vehicles and reduce emission.

The disposable income of residents and other charging on roads should also be considered to avoid excessive tolls.

The methods of charging fees calculation and reasonable verification methods are summarized as follows:

  1. Model calculation and optimization

  2. Verify rationality of congestion charging fees by the commuting time.

  3. Use income method to verify rationality of congestion charging.

  4. Use parking fee to verify the rationality of congestion charging.


Congestion Charging Technology

As the core element of congestion charging, information acquisition technologies of electronic toll system include:

  • Multi-lane free flow system based on ETC

  • Licensing plate recognition system based on image and video capture

  • Charging system based on RFID

  • Charging system based on satellite positioning


The technologies mentioned above can be used together and combined with the monitoring of pollutant emission reduction, in order to meet the dual purposes of toll and inspection and the ultimate goals of congestion elimination and pollution emission reduction.

Monitoring and Evaluation

The experience of London and Singapore in congestion charging shows that,with the development of social economy and changes in transportation policy, congestion charging may gradually lose its regulatory effects. For example, London has vigorously promoted non-motorized transportation in toll regions, by which the road area for motor vehicles reduced by 40%, and the traffic pressure of roads in charging areas has increased.

Therefore, traffic monitoring and evaluation system should be established for congested toll regions or roads, and real-time monitoring should be conducted within toll areas and in surrounding areas. Charging fees should be adjusted periodically, and transportation policy that may have impact on charging areas should be evaluated, so as to ensure the effectiveness of congestion charging policy.

8. The openness and transparency of the fund is of great public concern. How can it be achieved in congestion charging?


How to allocate and use the revenue is of great importance in the implementation of the policy. First, government should allocate and use it rationally and reveal the information.  According to WRI's report "Analysis of Public Opinion on Congestion Charging Policy in Beijing in 2016", most interviewees and interviewed organizations hoped the revenue to be used on improving or subsiding publication to improve the public traffic infrastructure. Therefore, municipal government should clarify the managing method and use of the income and had better invest transportation system especially public transportation system and reveal the charging collecting and using information of the revenue to improve public's trust on government. Considering international experience, Transport for London was authorized to allocate the revenue, but can only spend it within the field of transportation. The income is allocated to every fields in traffic, including system operating, subsidy on public transportation, bridges and roads improvement and the building and improving of slow-moving traffic like bicycle track and pedestrians' road crossing facilities. Transport for London makes public all infrastructures built or maintained with the income of congestion charging, which illustrates the benefits of the policy to the public effectively.

Moreover, the degree of public's trust on congestion charging policy relies largely on if government can use the revenue in an open, transparent and fair way. Stockholm rises congestion charging policy to a national level's tac policy and when collected, the revenue is included in the national budget and is controlled by the parliament, which is used mainly to build infrastructures in Stockholm and surrounding counties. The investment flow of each fee is indicated on the public annual tax return. This makes the revenue and expenditure of congestion charges very transparent, ensuring the credibility of the policy.

9. How to ensure the participation of the public in the process of implementing the congestion charging policy?

As a public policy, many interest groups are involved in congestion charging policy. The participation of the public in the formulation of the congestion charging policy can improve the fairness of the policy and the public's adaptability and support to the policy. According to the Public Survey covered 10 thousand people conducted by the World Resources Institute and Beijing Jiaotong University in 2016, about 33.0% of respondents expressed their wish to participate in the formulation of policies. In addition, there is a significant positive correlation between the level of understanding of policies by the people and the organizations and the support for the policies.

In the process of designing congestion charging policy, municipal governments can design clear and effective public communication and publicizing measures and build up smooth communicating approach, like setting up website and hotlines, holding hearings and making public details of policy on time. Governments should also hear the voice of public, ensure people's participation and have positive contact with the masses. Singapore government has broken through the tradition when promoting the electronic road charging system to the public by adopting innovative public communication methods, communicating relevant information to the public in an open and transparent manner, and consistently integrating public participation into the electronic road charging system. In the whole process of implementation, operation and management, this provides a favorable condition for obtaining public support to congestion charging policies and establishes a good image of the government. In terms of the scale and coverage of public participation, Singapore fully absorbs the opinions from “unofficial”, so that as many groups and the public as possible can participate in the whole process of policy making, thus avoiding “forced hearings” after policy making and before the implementation. Conducting social communication and publicizing in this way, which emphasizes communication first, uses different strategies and considers different periods, also promotes the acceptance of society.


10. What other experiences have been successful in implementing congestion charging policies?


In Stockholm, the ruling Social Democratic government decided to conduct a trial of the congestion tax for a period of time before the referendum in order to fulfill its commitment to the Green Party. In January 2006, Stockholm officially began to test the congestion tax, and collected taxes on different times in the warning line around the inner city. The main reason for the public to oppose the congestion tax is that it does not think that the congestion tax can reduce congestion. During the test period, the traffic flow inside the warning line during the charging period has dropped by 20%~25%, and the pollutants within the warning line (CO2, NO and PM) emissions are reduced by approximately 14%. With the gradual emergence of the test results, the public and media support rates have also undergone earth-shaking changes. The trial was a great success and received a public support rate of 51.3% in the referendum. In August 2007, the congestion tax policy was officially implemented, and the effect has been good so far. According to Swedish experience, it is recommended to conduct a trial operation of the policy before the congestion charging policy is officially implemented, so that the public can experience the benefits brought by the policy, including the improvement of traffic congestion and the improvement of air quality, and also reduce the negative concern impact on congestion charging.

During the implementation of the policy trial, all relevant departments can also find defects in theoretical research, so as to timely adjust the policy and formulate a more complete formal implementation plan. After the pilot, the local government can conduct a scientific assessment of the effectiveness of the policy and publicize the results in due courses. The pilot provides a buffer zone for the public to accept the policy, allowing the congestion charging policy to be implemented step by step.

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