Stuttgart is the capital of Baden-Wuerttemberg and forms with about 600,000 inhabitants the centre of the Stuttgart Region, which boasts in total 2.7 million inhabitants and employs 1 million people. Europe’s strongest region in terms of exports supports its strength through the automotive and mechanical engineering sectors. Companies such as Daimler and Porsche enjoy an excellent reputation worldwide. Several universities and numerous research institutions form together a diversified research landscape. Stuttgart is well-acquainted with all its transport-related challenges, which result from high mobility demand from citizens and the economy. Nonetheless, the city is also working hard on solutions for urban mobility aimed at increasing the quality of life and at reducing the negative impact of traffic on the environment.
CoEXist use cases in Stuttgart
Despite the city of Stuttgart has an excellent public transport system, a state of the art traffic management centre and has made several improvements for cycling, the city’s topography and the resulting network structure affect the reliability of the urban transport network. Congestion on the motorway can also influence the traffic flow in the urban area.
For this reason, the city is eager to explore what are the impacts of the Connected and Automated Vehicles (CAVs) on road infrastructure and to what extent they can alleviate the traffic congestion in the city and its surroundings. Two uses case are foreseen for the city of Stuttgart within CoEXist:
Impacts of CAVs on travel time and mode choice on a network level
The first use case of Stuttgart is based on the assumption that CAVs of levels 3 and 4 will influence mode choice as cars become more comfortable and CAV users will experience various advantages including:
- shorter or more reliable travel times due to increased capacity,
- possibility to use in-vehicle time more efficiently,
- lower parking search, access and egress time with the introduction of valet parking.
This may lead to a modal shift and can influence route choice, if some roads are more suitable for CAVs.
The City of Stuttgart is particularly interested in the potential impacts of CAVs on the traffic situation in and around the city, as Stuttgart suffers from congestion problems. The local authorities want to better understand the extent to which CAVs can improve the traffic flow. The local authorities would also like to determine if CAVs will increase urban car traffic.
Some preliminary results show that the introduction of CAVs has a limited but certain impact on the local modal split as well as on the total number of kilometers traveled and travel times. The first results where calculated for a situation where CAVs would represent about 80% of the private vehicles. As car drivers using a CAV can use some of today’s driving time for non-driving activities, it is assumed that the perceived travel time will decrease by up to 30% (i.e. people will accept to spend more time in vehicles).
For this setting, model applications by the University of Stuttgart indicate a slight modal shift from public transport and active modes to cars. As car travelers would use some of the time gains to travel further, however, it is expected that the total kilometers traveled by car will increase by around 15%.
Impact of driverless car- and ridesharing services
The second use case takes a different angle. With the emergence of fully automated CAVs (level 5), car-ownership and driving licenses become obsolete and are not needed anymore to travel by car – in particular if ride- and car-sharing options are available. Therefore, the City of Stuttgart investigates the extent to which the introduction of fully automated ride- and car-sharing systems, capable of operating without drivers in the Stuttgart Region, can influence transport supply and travel demand.
Since Stuttgart suffers from heavy congestion problems, the City also want to determine if and to which extent automated car- or ride-sharing services can improve or worsen the situation.
The first results of the research made by the University of Stuttgart considers a situation in which all private cars and busses are replaced by fully automated cars, able to operate in a ride-sharing system. In this situation, people accept to share rides.
In this scenario, most of the car travelers would shift to ride-sharing services. As the potential for pooling is limited and as buses are replaced by smaller ridesharing vehicles, the kilometers traveled would decrease only slightly. However, the total number of vehicle needed to transport people could be substantially reduced, to only a quarter of the current number of vehicles, thus saving on space for parking and other types of activities.