Simulation study (2017) on replacing private cars with public transport, shared taxis, and shared cars

Replacing private car traffic with new shared mobility services (like public transport, shared taxis, and shared cars) in urban areas dramatically reduces the number of vehicles needed, significantly cuts CO2 emissions, and frees large swathes of public land for uses other than parking, without making it more difficult for users to get from door to door.

Simulation study

These initial results (from the 2017 study) from shared mobility simulations using mobility data from Lisbon (Portugal) have now been largely confirmed in a further study using data and focus group results from Helsinki (Finland).

In the simulations, motorized road trips (private car, bus, and taxi) trips were replaced by different configurations of 6-seater Shared Taxis that provide on-demand door-to-door service and Taxi-Buses that offer a street corner-to-street corner service booked 30 minutes in advance.


With these shared services, all of today’s car journeys in the Helsinki Metropolitan Area could be provided with just 4% of the current number of private vehicles.

The best results in terms of reducing emissions and congestion are achieved when all private car trips are replaced with shared rides:

  • CO2 emissions from cars would fall by 34% (based on traditional fuel technology).
  • Congestion would be reduced by 37%.
  • Much of the public parking space could be used for other purposes.

Improved quality of service

Shared mobility also means fewer transfers, less waiting, and shorter travel times than traditional public transport. The improved quality of the service could attract car users who currently do not use public transport and foster a shift away from individual car travel.

The Helsinki study also confirms initial results for Lisbon that shared mobility improves access to jobs (and public services), notably for citizens in areas with few such offers. Shared mobility services thus can play an essential role in creating more equitable access to opportunities for citizens.

The Helsinki study confirms that shared mobility services can be highly effective feeder services for high-capacity public transport services. As in the Lisbon case, scenarios providing first- and last-mile shared services could increase rail and metro ridership between 15% and 23%.

Lisbon versus Helsinki

The benefits of shared mobility for the Helsinki Metropolitan Area were highly significant in the simulation yet lower than in the Lisbon case. Replacing all motorized road trips (private car, bus, and taxi) with shared services reduced transport CO2 emissions by 62% in the Lisbon case, while the reduction for the Helsinki Metropolitan Area was 28%. This is because

  • The Helsinki region has a good public transport offer in international comparison, and people walk and cycle more. The current motorized road share in the Helsinki Metropolitan Area is 56% compared to 70% for Lisbon, meaning there is less room for improvement.
  • Average trip lengths in the Helsinki region are longer than in Lisbon, so emissions (based on traditional fuel engines)  will tend to be higher per trip for the same vehicle occupancy.

For the first time, a focus group and user survey complemented this shared mobility study. The feedback from potential users in the Helsinki region revealed that citizens are very optimistic about shared services as an additional tool to improve mobility in the Helsinki region. Potential users are very sensitive, however, to price and service quality.

Respondents want shared services available in the entire Metropolitan Area, not just in the city center. Shared services as feeders for rail and metro lines are seen as highly relevant. This squares well with simulation results showing that the service would require sufficient scale to ensure positive impacts and manageable costs.

In the survey, participants chose shared mobility services for 63% of all trips. There is some evidence, however, that public transport users in the Helsinki region are more willing than car users to adopt the new shared modes. Those aged 55 and above and those living far from the city center also tend to favour shared mobility.

The Helsinki region will use the study results in its regional long-term land use, housing, and transport planning process. The main aim of the process is to decrease emissions drastically by the year 2030.

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Walther Ploos van Amstel  

Passie in logistiek & supply chain management