The A-S-I approach - A holistic and sustainable
transport planning approach

Prof. Dr. Peter Heck, Man - aging Director of IfaS
(FH) Patrick Marx, Head of Department for Sustainable Mobility
Prof. Dr. Eckard Helmers, Director of IfaS
Dr. Michael Knaus, Head of Department for International Project Management
University for applied Sciences Trier, Environmental Campus Birkenfeld
Institute for Material Flow Management (IfaS) - Birkenfeld / Germany

(giz – German Service Provider in the Field of International Cooperation) proposed an interesting systemic transport planning approach. The A-S-I approach is based on the three consecutive steps Avoid, Shift and Improve (See Figure 1). In contrast to the traditional supply-oriented-approach in transport planning, the A-S-I approach is focused on the demand side and offers a more holistic approach for an overall sustainable transport system design.

   Figure1: A-S-I Approach (Deutsche Gesellschaft für Internationale Zusammenarbeit (giz) GmbH)

Figure (2) visualize how this concept concentrates on the mobility needs of individuals and tries to direct their decisions towards a more environmentally friendly option. In the first step “avoid” travelling should be reduced whereas in the second step “shift” citizen should be encouraged to use public transport instead of their own cars. The third step “improve” reflects the aim of reducing the car size and to offer a well-equipped infrastructure in the cities. (Deutsche Gesellschaft für Internationale Zusammenarbeit (giz) GmbH).

Please find a more detailed explanation of the A-S-I approach below.

Figure2: A-S-I approachexample(Deutsche Gesellschaft für Internationale Zusammenarbeit (giz) GmbH)


Before improving the transport infrastructure in a city the demand for travelling should be reduced as far as possible. That could be achieved by an intelligent urban planning concept lowering the distances between the facilities important for daily live. The Canadian city Vancouver serves as an example for sustainable urban planning. The policy maker avoided not only land use but also focused on improving the quality of live in the city. Aside greening the city and ecologic oriented construction, the number of cars in the inner city had been reduced during the last 20 years despite increasing population. Currently, Vancouver ranges among the most lively cities around the world. The secret behind is to prioritize first pedestrian circulation followed by cycling, third public transport and as a least option cars. (Steffen & Gore, 2008).

Furthermore reducing the need for mobility has an important social aspect. Especially lower-income citizen are less disadvantaged when main facilities such as shopping malls and facilities for health care and education are within walking or cycling reach. (Runge & Becker, 2006) Another possibility for an avoidance strategy is to encourage teleworking.


The city authorities have two basic possibilities to influence the behavior of their citizen. There are so called push and pull measures. While pull measures gives incentives push measures force with penalties. Figure 3 shows the results of behavioral effects of push and pull measures in an experiment of the Helmholtz Center for Environmental Research (UFZ). (Helmholtz Centre for Environmental Research, 2007)

Figure 3: Behavioral effects of the introduced policy measures, Modified according(Helmholtz Centre for Environmental Research, 2007)

In this experiment the UFZ analyzed the impact of offering an express bus to the inner city as a pull measure and as another option the introduction of an inner city toll. Although this experiment is not representative it could demonstrate that with both measures the behavior could be influenced significantly. The use of public transport increases likely in both scenarios while bike usage is higher with an inner city toll and less when an express bus is offered.

Another instrument to shift decisions to a more environmental benefit is to link these decisions with positive emotions. Following a publication as an output of the EU project “Trendy Travel” supported by the program Intelligent Energy Europe more than half of human decisions are emotional. Consequently, the choice for a specific transport mode is not always a rational decision. It is not sufficient to provide information only about the impacts of the different mobility possibilities. Walking, cycling and the use of public transport should be associated with positive emotions. (EU project Trendy Travel)


Aside reducing the car size and improving the infrastructure for pedestrian circulation, cycling and public transport, it is also essential to optimize automobiles with respect to fuel efficiency, fuel type and emissions. There are few technical alternatives so far. The production of biofuels suffers from food competition (“tank-plate-discussion”), while the usage leads partly to toxic emissions. Fuel cell cars propelled with hydrogen suffer from low energy conversion rates, extremely high prices and lack of fuelling infrastructure. The only technical alternative available to the market so far is the electric car ensuring good energy efficiency, nearly zero local toxic emissions and convincing carbon footprint if – and that´s essential – the energy consumption is produced by renewable energy sources.


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