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Occupancy rate of vehicles

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Complete with results
Project website
Project Acronym
SVI 1997/058
STRIA Roadmaps
Transport mode
Road icon
Transport sectors
Passenger transport


Background & Policy context

The occupancy rate of cars (AOC) is used in most transport studies as an exogenous indicator and is rarely the object of investigation by itself. Transport planners mostly only have occupancy rates of passenger cars due to experience values as well as the lack of verified know-how for the determination of this important indicator in transport planning.

Targets according to SVI-tender of the research paper of 9 February 1996:

 magnitudes of influence indicators and their impact on the occupancy rate;

  • overview of mean values for the relevant parameters including range;
  • discussion on the manipulation possibilities.


The whole research project was carried out in accordance with research contract 1997/052 'Carpooling (ICARO)'.


The research project investigates which variables have an influence on the occupancy rate of cars (AOC) and which measures in the domain of traffic management and offer are suitable to increase the AOC. The analysis contains qualitative (utility value analysis) and quantitative elements. It is based partially on existing evaluations of surveys in Switzerland (microcensus) which are analysed in detail. The analysis also contains evaluations of experiences/projects on carpooling abroad which were tried to transfer to Swiss conditions. Based on an evaluation of different measures, HOV (high occupancy vehicles) lanes are investigated with two standardised situations in detail. The analysis ends with recommendations to policy.


The following tasks were developed:

  • Evaluation of the Microcensus transport survey 1994 data;
  • Literature analyses as well as evaluation of related findings;
  • Analysis of previous Swiss and foreign experiences made with the manipulation of the AOC;
  • Derivation of planning aims for Switzerland with regard to the increase of the occupancy rate of vehicles;
  • Derivation of single measures for the increase of the occupancy rate of vehicles;
  • Qualitative appraisal of measures as well as value benefit analysis acorrding to weighted criteria (among others effectiveness, transport modification potentials, efficiency, feasibility);
  • Extensive analysis of the 'Preference of HOVs on carpool lanes';
  • Definition and transport-related appraisal according to two standardised situations.


Parent Programmes
Institution Type
Private foundation
Institution Name
Association of Transportation Engineers
Type of funding
Public (national/regional/local)


For the last decades, the average non-distance-weighted occupancy rate of cars (AOC) in Switzerland has decreased from 2 to approximately 1.5 persons. The AOC related to commuter traffic (work + education) is especially low. Evaluations of different criteria associated with 'Mikrozensus Verkehr' have resulted in little knowledge about the variables of the AOC. The decreasing AOC is attributed to the increasing mobility and the higher degree in motorization. The consequences are increased shortage in road capacity and higher socio-economic costs. With a low AOC the narrow capacities are used inefficiently and resources are wasted. A turnaround cannot be expected in the near future. Resistance against further, mostly very costly, extensions of road transport infrastructures continues.

Therefore the question on appropriate political and technical interventions to increase the AOC rises. Increasing the AOC corresponds with an increase in car-pooling. It should not become an end in itself but be a part of overall objectives in traffic and transport. These overall objectives should help to prevent a generation of only 'unnecessary' mobility (additional person kilometres) and increased car-pooling at the expense of environment friendly means of transport (public transport, pedestrians, bicycle).

In Switzerland, Europe and North-America, several projects have been performed with the aim to increase the AOC. Beside some successes in the USA and some cities in Europe the outcome mainly looks disappointing. Many measures fail through human behaviour, infrastructure limitation and geographical restrictions or through bad communications. In general, measures with concrete incentives (financial or travel time savings) are more successful in changing the travel behaviour than measures that only increase people’s awareness of mobility choices.

There is a big discrepancy between the generally positive attitude to measures increasing the AOC and the effective behaviour of the individual. There are several conceivable measures to increase the AOC in Switzerland. These are described shortly in the report and rated according to criteria, mainly effectiveness, impact on traffic behavioural change and feasibility.

The following measures are considered for more detailed examination in this evaluation and qualitative rating:

  1. Set up of lanes for high occupancy vehicles (HOV)
  2. General increase of travel costs for the motorised individual traffic
  3. Organised h

    Policy implications

    The question on how to increase the AOC can neither be studied in isolation nor be effectively realised with single measures. Noticeable success requires a long-term, consistent and synergetic mobility management. The fundamental change in our behaviour towards mobility and turning back to supply-orientated traffic policy have to be stipulated as requested in several theoretical papers and partially established in some concepts. The new means in telematics can support such a turnaround.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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