Indicator Assessment

Passenger transport demand - outlook from OECD

Indicator Assessment
Prod-ID: IND-35-en
  Also known as: Outlook 026
Published 08 Jun 2007 Last modified 11 May 2021
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The OECD Environmental Outlook does not provide the direct answer to these policy questions but provides an indications on the developments in the transport sector globally.
The rapid increase in transportation activity seen in recent decades is expected to continue to 2030. Although air travel has been the fastest growing transport mode in recent decades, other modes have increased as well. 

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Global Air transportation volumes and GDP (1990 = 100)

Annual new vehicle sales by region to 2030

Transport externalities in Europe in 2004

The rapid increase in transportation activity seen in recent decades is expected to continue to 2030. Between 1970 and 2003, for example, air passenger travel in the US increased by 328% - nearly twice the rate of GDP growth during the same period. Air passenger travel in the EU  increased even faster, growing by over 1 200% between 1970 and 2003. Although air travel has been the fastest growing transport mode in recent decades, other modes have increased as well. 
Road transport, in particular, has grown faster than GDP in both the EU and North America. Transport growth is not only being driven by people/goods travelling further and more often, but also by an increase in the availability and use of motorised transport. In OECD countries, the private car has been the norm for decades, so only moderate increases in car ownership are predicted over the next 20 years. In non-OECD countries, on the other hand, rapidly rising incomes are expected to lead to large increases in vehicle ownership (Figure 16.3). In some cases, the increase in motorised transport is occurring at the expense of existing modes - some of which are less environmentally damaging than road transport. For example, bicycle use in China has fallen recently, as automobile use has expanded.

In OECD countries, road transport is responsible for most of the transport sector impacts on the environment, accounting for over 80% of all transport-related energy consumption, and for most air pollutant emissions, noise and habitat degradation (OECD, 2006a). In Europe (EU15, Norway and Switzerland), total external costs of transport (excluding congestion costs and externalities related to maritime transport) have been estimated at EUR 650 billion for 2000, or about 7.3% of total GDP (INFRAS, 2004). Climate change was the most important category, contributing 30% of total costs. Air pollution and accidents were the next most significant. In terms of transport mode, road transport has the biggest impact, generating 83% of the total estimated external costs. This is followed by aviation (14%), railways (2%), and inland waterways (0.4%). Road transport accounted for over 89% of the costs in all categories, except for climate change, in which road transport accounted for only 57% of estimated costs. Almost all the remaining costs associated with climate change came from aviation (41%). Two-thirds of all transport related external costs are caused by passenger transport and one-third by freight transport.

Maritime transport, although generally associated with lower environmental impacts, continues to raise concerns, mainly due to oil pollution from major accidents, as well as (accidental or deliberate) discharges of waste products. The maritime shipping sector is also an important contributor to NOx and SO2 emissions, as well as to ozone pollution. There is also growing concern over the environmental impacts of air traffic, which continues to increase rapidly mainly due to increased tourism. The rail sector is generally the most environmentally benign form of transport, but is also the least used.

Key uncertainties, choices and assumptions
There are fundamental uncertainties in projecting transport demand and simulating future transport systems. Uncertainties in demographic, economic, technological and institutional factors will affect the actual level of future transport demand, the mix of energy supplies consumed, and the associated rates of (for example) CO2 emissions. Knowledge is limited of the complex interactions of technological, cultural and political forces that determine the development of national transport schemes. It is therefore not certain that today's relationships will persist unchanged for the next 25 years. For non- OECD countries, it is also difficult to find reliable and consistent data on which to base future projections.

Supporting information

Indicator definition

The indicator "projected passenger transport demand from OECD environmental outlook" is presented as the European transport activity by modal split (passenger cars and motorcycles). The indicator covers the period of 1990 - 2020 with 5 year intervals, in billion vehicle kilometer traveled.


Billion vehicle kilometer traveled


Policy context and targets

Context description

Pan-European policy context

The large number of non binding policy instruments have been developed under fora such as Environment for Europe process, the European Council of Ministers of Transport (ECMT) and the UNECE/WTO Transport, Health and Environment Pan-European Programme (The PEP). The PEP was set up to address the key challenges to achieve more sustainable transport patterns and a closer integration of environmental and health concerns into transport policies.

EU policy context

The EU has set itself the objective to reduce the link between economic growth and passenger transport demand ('decoupling') in order to achieve more sustainable transport.

Reducing the link between transport growth and GDP is a central theme in EU transport policy for reducing the negative impacts from transport: 

  •  The objective of decoupling passenger transport demand from GDP was first mentioned in the Transport & Environment (T&E) integration strategy that was adopted by the Council of ministers in Helsinki. Here, the expected growth in transport demand was named as an area where urgent action was needed. In the sustainable development strategy that was adopted by the European Council in Gothenburg, the objective of decoupling is set in order to reduce congestion and other negative side-effects of transport.
  • In the review of the T&E integration strategy in 2001 and 2002, the Council reaffirmed the objective of reducing the link between the growth of transport and GDP.
  • In the Sixth Community Environmental Action Programme, decoupling of economic growth and transport demand is named as one of the key objectives in order to deal with climate change and to alleviate health impacts from transport in urban areas.

Shifting transport from road to rail is an important strategic element in the EU transport policy. The objective was first formulated in the Sustainable Development Strategy (SDS). In the review of the T&E integration strategy in 2001 and 2002, the Council states that the modal split should remain stable for at least the next ten years, even with further traffic growth.

In the White Paper on the Common Transport Policy (CTP) "European Transport Policy for 2010: Time to Decide", the modal shift is central and the Commission proposes measures aimed at the modal shift.

The White Paper on the Common Transport Policy also says that common transport policy alone will not provide all the answers. It must be part of an overall strategy integrating sustainable development, to include: a) economic policy and changes in the production process that influence demand for transport; b) land-use planning policy and in particular town planning; c) social and education policy;  d) urban transport policy; e) budgetary and fiscal policy to, to link the internalisation of external, and especial environmental, costs with competition of trans-European network; f) competition policy, to ensure, in line with the objectives of high-quality public services, and in particularly in rail sector, that the opening-up of market is not harmed by the dominant  companies already present on market; g) research policy for transport in Europe.

The European Neighbourhood Policy stressed that generating more trade and tourism between the Union and its neighbours, requires efficient, multimodal and sustainable transport systems. EU should develop an Actions plan for cooperation with its neighbors to improve the physical transport networks connecting the Union with neighboring countries, to step up aviation relations with partner countries with the aim to open up markets and to co-operate on safety and security issues.  The Action Plans will also contain specific provisions to address the vulnerability of transport networks and services vis-A-vis terrorist attacks. The highest attention will be paid to enhance the security of air and maritime transport.

EECCA policy context

EECCA Environmental Strategy recognizes the need to incorporate environmental concerns into transport policies and sets this action as one of the Strategy objectives.

One of the actions selected by THE PEP is 'demand side management and modal shift and with special attention to the needs of the countries of Eastern Europe, Caucasus and Central Asia (EECCA) and of South-Eastern Europe, as well as issues related to ecologically particularly sensitive areas'.


Structural goals and targets

  • Implement transport strategies for sustainable development (WSSD

Pan-European level


  • To increase railway passenger share from 6 to 10% by 2020  (COM 2001/ 370)
  • '...a shift in transport use from road to rail, water and public passenger transport ... '  the share of road transport in 2010 is no greater than in 1998" (EU Sust. Dev. Strategy, 2001)
  • modernization of transportation facilities, including use of less energy intensive transport modes ( EECCA Strategy)

Efficiency targets


  • Decouple transport growth significantly from GDP   ( 6th EAP)
  • A switch to more efficient and cleaner forms of transport including better organisation and logistics" ( '6EAP')


Link to other policy goals and targets


  • '...develop transport infrastructure further through ... networks, better trafic management ... An intermodal approach' (ECMT, Council of Ministers, 1997)


  • Noise from transport is reduced and is no longer presents a health concern (reference policy document?)
  • 140g CO2 average passenger car fleet emissions by 2008
  • 120g CO2 by 2012 (EC/industry agreement)
  • '...give priority to infrustructure investments for public transport and railways...' (EU Sust. Dev. Strategy, 2001)
  • Open up rail markets and support new rail infrastructure
  • '...Link sea, inland water and rail transport...' (COM 2001/ 370)
  • Extention of pan-European transport corridors to neighbouring areas (2004 Santiago de Compostela Conference)
  • Motorways of the Sea: operating by 2010  (TEN)
  • 'introduction of road pricing' (EU Sust. Dev. Strategy, 2001)
     "promoting measures to reflect the full environmental costs in the price of transport" (6EAP)
     Promote more balanced regional development (EU 2001 Sust. Dev. Strategy)
     Link sea, inland water and rail transport
     Improve efficiency of intermodal services (2001 White Paper on Transport)


  • Develop and implement national transport strategies for sustainable development to: improve affordability, efficiency, convenience, GHG emissions, urban air quality, health ( EECCA Strategy)
  • introduction of incentives for sustainable transport, including public transport  ( EECCA Strategy )
  • Introduce vehicle and fuel standards ( EECCA Strategy)

Related policy documents



Methodology for indicator calculation

The projections of the European transport activity by modal split are based on the results of the MOVE II model under reference case scenario presented in the OECD Environmental Outlook, 2001.

The outputs of the following models are used as an input in MOVE II model:

- JOBS for economic developments

- MOBILE 6, COPERT and others for detailed emission calculations

Overview of the MOVE II Model

The system is based on a calculation of the number of kilometers driven in a given region for each technology and each vehicle type in a given calendar year. For a given region and vehicle type, the age distribution vehicles were also estimated. Based on the age distribution, and knowledge of the emissions standards adopted or expected to be adopted in each country, a table was created which determined the technology type for each model year, the number of vehicles of that technology type in a given calendar year and the number kilometers driven by vehicles using that technology. Vehicle categories included light duty gasoline vehicles (passenger cars), light duty diesel vehicles, light duty gasoline trucks (including so called sport utility vehicles), light diesel trucks, heavy duty gasoline trucks and buses and motorcycles (including scooters). Emissions of each pollutant (CO, VOC, NOx, N2O, CH4 and PM were then combined for each vehicle type for calendar years between 1990 and 2030. The emissions were calculated with the results of the detailed emission calculation models (e.g. MOBILE 6, COPERT an others).

The three primary drivers leading to increases in world's vehicle fleets are population growth, increased urbanization and economic improvements. The development of these drivers for the reference case was projected based on the eco-classical equilibrium model JOBS (see more about the model here).

Reference scenario:

The Reference Scenario is based on current activities and trends. It does not take into account the adoption or implementation of new policies.

The base year for the outlook was 1995. The historical data for the vehicle stock were takes from the OECD statistics for OECD countries. Statistics for other regions where taken from the UNECE and The International Organization of Motor Vehicle Manufacturers. The total fuel use and fuel split was taken from the IEA statistics (based on the phone interview with Mr. Peter Wiederkehr).

The base year data used in JOBS model were mostly taken from GTAP (Global Trade Analysis Project, Version 4) data base developed by Purdue University with 1995 as a base year. In addition to the base year data, assumptions are made in the Reference Scenario concerning:
- total GDP developments (based on OECD Economic Developments projections);
- population growth (based on UN median fertility estimations).

Methodology for gap filling

1) Ideally one would calculate emissions for each country of the world separately, recognizing the reality that every country is different at least in some important respects. However, such an approach would be prohibitively burdensome and time consuming. Instead the World was divided into regions where the similarities between them were broad enough to provide reasonable emissions estimates. Major factors which were considered were emissions regulations, vehicle types, economic conditions and growth forecast, etc.

2) The data for vehicle stock in non-OECD regions is rather poor. In order to fill the gap the UNECE data were combined with the data from the International Motor Vehicle Association.

Methodology references

  • OECD Environmental Outlook The Methodology for the Move II model is describes in the Annex 2. In order to find out some specific information regarding the reference case and the data input an interview with Mr. Peter Wiederkehr was conducted. (15 September, 2006) Dr. Peter Wiederkehr Federal Ministry of Agriculture, Forestry, Environment and Water Management Division V/5, Transport, Mobility, Human Settlement, Noise Stubenbastei 5 , A-1010 Wien Tel: +43 (0)1 515 22 1205; Fax: +43 (0)1 515 22 7208 e-Mail:


Methodology uncertainty

To answer the policy question 'Is there in Europe a trend of decoupling of passenger transport demand from economic growth?' it is necessary to calculate the decoupling indicator, e.g. as the relation between the total volume of passenger transport (inland modes) and GDP (Gross Domestic Product). Ideally, it should be possible based on the data from the volume of transport activity for a region. However with the existing data it is hard to construct such decoupling indicator for the Former Soviet Union. This region is presented as a part of non-OECD countries together with together with Latin America, China, South East Asia, Africa. Should the methodology spreadsheets be available it should be possible to obtain there data.

In order to answer the specific policy question: 'Is there in Europe a trend of reduction of car passenger transport and increase of rail passenger transport in total inland passenger transport in relative to other modes?' a modal split of a passenger transport should be presented for all transport categories. In the existing in OECD Outlook 2001 data the passenger transport include only road transport. Information for the rail passenger transport as well maritime transport is missing. It should also be noted that the modal spilt data are presented at the global level. Should the methodology spreadsheets be available it should be possible to obtain these data.

Model related uncertainty: The Move II model is static in the sense that all changes are introduced by the user. This provides on the one hand more flexibility to the user, but on the other hand, no checks for consistency or plausibility of the changes are done by the model. (based on the phone interview with Mr. Peter Wiederkehr).

Data sets uncertainty

1) Input data to Move II model:
The historical data taken from the international sources for the countries of the Former Union were not always accurate; some assumptions had to be made. It is unclear what these assumptions were. (based on the phone interview with Mr. Peter Wiederkehr).

More on the uncertainties regarding input data can be found in the Outlook indictors from IEA/SPM model.

2) Output data from MOVE II model:
In the OECD Environmental outlook the outlook data for transport activity by modal split is presented at global level. Disaggregated datasets for Europe should be requested.

Rationale uncertainty

No uncertainty has been specified

Data sources

Other info

DPSIR: Driving force
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • Outlook 026
EEA Contact Info