Gothenburg is transforming from an industrial port city to an urban city focusing on the tertiary sector. Thus, the second-largest city of Sweden is transforming old industrial quarters into new residential- and commercial buildings, which create large long-term construction sites. Furthermore, these transformations also led to an increase in cycling as a sufficient and fast alternative mode of transport. Both these phenomena are the basis for the two use cases: one focusing on shared spaces in the city center of Gothenburg and the other on AV traffic in tunnels, which are under construction.
The shared space use case, which was modelled in the Vissim modelling tool, is located in the city center of Gothenburg, an area highly frequented by cyclists, pedestrians and public transport. The introduction of AVs in a shared space created impacts on conventional vehicles and minibuses on all the investigated traffic performance metrics. These conditions improved, once more advanced AVs were deployed. Although, vehicle traffic performance is negatively affected, vehicle demand is served and there is no breakdown due to interactions between AVs and active modes. Since pedestrians and cyclists are always given the right of way by the AVs, the overall safety in shared spaces increased with the introduction of AVs. Nevertheless, this leads to delays of AVs and motorised vehicles, especially if zebra crossings are introduced. As pedestrians and cyclists are given the right of way, AVs cannot react as quickly to use the breaks in the flow of pedestrians.
In contrast to the above-mentioned microscopic use case, Gothenburg also took a macroscopic look at AVs. Long-term construction is a common issue in cities like Gothenburg, thus it is important to ensure that the introduction of AVs does not imply further negative effects and investigate which measures can improve traffic during extended construction periods. Therefore, two measures have been tested, including a two-way AV-only tunnel tube under the Göta river, as well as a reserved bus and AV lane on the major motorway network.
If the two-way tunnel is only used by AVs, one can observe different effects. Low-level AVs just marginally increase the travel time through the tunnel, as no obstacles need to be avoided. Decrease in travel time can already be observed with introduction of advanced AVs, an effect which is even significantly increased once prevalent stages of automated vehicles are reached. Traffic flows are also improved in the larger framework, as AVs are directed through the Göta tunnel, freeing up space for conventional vehicles in other parts of the city. For the bus and AV lanes on the Gothenburg motorway network, only marginal increases in travel time and delays for conventional cars occur. Additional and more advanced AVs do not bring any significant positive results, as the dedicated AV lane becomes more crowded.
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