Frequently Asked Questions

  • How were the rankings calculated?

    In short, all cities were assigned a percentage relative to the other 99 cities, and ranked on that percentage. The lowest scoring city (e.g. the city with the highest number of traffic fatalities per 100,000 inhabitants or the highest delays) receives a 0% and the highest receives 100%. All cities in between are assigned a proportional score. The city that is assigned an 100% in the public finance indicator does not commit 100% of its city budget to transport spending, rather it commits a larger share of its city budget to transport than the other 99 cities. The indicators were weighted and then each city is given a ranking in the sub-index. Then a city’s ranking across all three sub-indices is averaged to give the city its overall ranking.

    In more detail, The Sustainable Cities Mobility Index is constructed with a three-stage averaging process to create a composite score and corresponding ranking for each of the 100 cities.

    The overall Index score for each city is based on the city’s performance in 23 individual indicators listed in the Appendix. For each indicator, the same set of steps is followed which allows us to assign a value between 0 percent and 100 percent to each city:

    Firstly, in each indicator, raw scores are found for each city. For example, in the modal split indicator, the percentage of all trips taken by public transport is given for each of the 100 cities on the Index.

    • • All raw scores are compared and the standard deviation for the statistical dataset is computed. To account for outliers, each data point is checked to determine if it falls outside of 2 standard deviations (s.d.) from the mean. If a data point for a specific city does fall outside the mean +/- 2 s.d., the city is assigned a value equal to either the mean +2 s.d. or the mean – 2 s.d.
    • • To calculate an Index score for each city, a minimum-maximum approach is used to assign a city a score between 0 percent and 100 percent. The lowest scoring city (after accounting for outliers) is assigned a score of 0 percent and the highest scoring city is assigned a score of 100 percent. All city scores in between the minimum and the maximum are assigned a proportional score specifically using the formula (data point – series min) / (series max – series min).
    • • Given that a higher overall Index score indicates a better performance, for indicators where a lower figure is deemed positive (such as traffic fatalities), the inverse of the data point or its negative equivalent were used.
    • • In the rare case that a data point for a particular city was not available, the average score of the indicator was used in its place.

    Once scores between 0 percent and 100 percent were assigned to each city in each indicator, the individual indicators are then grouped into one of three broader sub-indices – People, Planet and Profit. Of the 23 individual indicators, 10 sit within the People sub-index, seven within Planet, and six within Profit.

    The People sub-index measures the social and human impacts of the city’s mobility system, such as coverage of the transport network and wheelchair accessibility, efficiency and upkeep of a metro system, and digital capabilities on the city’s trains and buses.

    The Profit sub-index assesses the economic aspects of a city’s mobility system. This encompasses key metrics for commuters, such as time taken to get to work and affordability of the public transport network, as well as the city’s financial commitment to their transport infrastructure.

    The Planet sub-index measures the environmental implications of the city’s mobility system, including metrics such as air pollution, greenhouse gas emissions, electric vehicle incentives, and green space.

    A weighting system is applied to the calculation of sub-index scores. To determine the weightings, the individual indicators are ranked from most important to least important in terms of how appropriate and reflective the indicator is as a metric for urban mobility. The most important metric is then assigned the highest weighting while the least important receives the lowest. The weights for the variables in between are spread evenly. To see the highest to lowest rankings for each indicator, please see Table 2 in the Appendix of the report. After sub-index scores were calculated for each of the 100 cities, a simple average is taken of all three to create the final Index scores and rankings.

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  • Who did the research?

    Arcadis commissioned the Centre for Economics & Business Research
    (www.cebr.com) to conduct the research. They are a well-respected economics consultancy based in the UK.

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  • How were the cities chosen?

    The cities were chosen as a representative sample of 100 leading cities in the world spread across the continents. They represent a wide geographical, political and economic range as well as varying urban sustainability challenges. They were also chosen as cities that have sufficient available data to allow for international comparison.

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  • What sources were used to compile the Index?

    For the Index, Arcadis commissioned the Centre for Economic and Business Research (Cebr), a recognized and established research firm and their team of senior economists to compile the information. Cebr used their vast databases and connections to compile the data from globally credible sources (i.e. the World Health Organization, CDP, Siemens etc.) Most sources are publicly available and all are listed in Table 1 in the Appendix of the report.

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  • Why is Hong Kong first?

    Boosted by its innovative and well-connected metro network and a high share of trips taken by public transport, Hong Kong manages to achieve many of the aims of an effective urban transport system – enabling comprehensive mobility, creating economic opportunity and enriching the lives of citizens, business and tourists alike. Hong Kong ranks first in the overall Index and in the People sub-index, 53rd in Planet, and sixth in the Profit sub-index.

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  • What are the most balanced cities between People, Planet and Profit?

    We do not see a single city make the top ten in all three pillars (People, Planet and Profit). Only London, Singapore and Paris make the top twenty in all three pillars. Hong Kong is first in people, 53rd in planet, and sixth in profit.

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  • What exact indicators were used?

    These 23 criteria were selected by Arcadis subject matter experts. The indicators used to reflect the criteria were sourced by Cebr who was commissioned by Arcadis to conduct the actual research. The indicators were selected on the basis of the information being available across all cities, the source credibility, and more. All indicators, explanations, and weightings justifications are in the Appendix of the report.

    People: Fatalities, Access to Transport Services, Modal Split of Trips Taken, Upkeep of the Metro System, Wheelchair Access, Uptake of Active Community, Transport Applications and Digital Capabilities, Airport Passengers, and Hours of Metro Accessibility

    Planet: Transport Greenhouse Gas Emissions, Provision of Green Space, Congestion and Delays, Bicycle Infrastructure, Air Pollution, Efforts to Lower Transport Emissions, and Electric Vehicle Incentives

    Profit: Commuting Travel Time, Economic Opportunity, Public Finance, Efficiency of Road Networks, Affordability of Public Transport, Utilization of the Transport System.

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  • How are the indicators weighted?

    A weighting system is applied to the calculation of sub-index scores. To determine the weightings, the individual indicators are ranked from most important to least important in terms of how appropriate and reflective the indicator is as a metric for urban mobility. The most important metric is then assigned the highest weighting while the least important receives the lowest. The weights for the variables in between are spread evenly. To see the highest to lowest rankings for each indicator, please see the Appendix of the report. After sub-index scores were calculated for each of the 100 cities, a simple average is taken of all three to create the final Index scores and rankings.

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  • Does the Index measure metropolitan areas or the area within the geographical bounds of the city?

    The data availability limits to the city limits in most cases.

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  • How many of the indicators are city level and how many are national?

    City-level data are used wherever possible, though in some cases only national-level data exists. Where there is no comparable city-level data across countries, the national value is taken and a national database is used to scale the cities so that they are given a spread around the national average. There were no indicators in this Index that rely solely on national level data for all cities. Two indicators, Greenhouse Gas Emissions from transport and Bicycle Infrastructure are a combination of city and national level data.

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  • How do I get in touch?

    If you still have more questions or are a member of the press looking to get in touch, please e-mail us at cities@arcadis.com

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