## 3 The Approach of This Special Issue  
This Special Issue puts together papers with different focuses, but all of them tackle the topic of smart mobility as defined and discussed above. The topic of integration of mobility into the wider city perspective is addressed within the paper \"Interdisciplinary Urban Tunnel Control within Smart Cities\" [6]. The paper has two major contributions. First, it provides a systematic view of an urban road tunnel with a focus on the interfaces between the tunnel and the rest of the city and the way they are managed. A tool to consider a sustainable development of a tunnel (i.e., not only traffic flow parameters such as average speed but also environmental and societal characteristics) is provided. The second contribution is that it provides a new urban road tunnel control approach that follows the original methodology and systemic view described in the paper. If the tunnel is controlled autonomously, which corresponds to the current state of the art in many cities, the algorithm decides to close it based on only local parameters. However, the proposed new algorithm takes into consideration not only the traffic situation in the tunnel (as expressed by the parameter traffic density) but also the actual traffic situation within the city (as expressed by its level of service (LOS)). This allows more environmentally, socially, and economically sustainable management of urban road tunnels. The topic of city logistics using new and environmentally friendly travel modes is addressed in the paper \"A Geometrical Structure-Based New Approach for City Logistics System Planning with Cargo Bikes and Its Application for the Shopping Malls of Budapest\" [7]. In this paper, the authors provide a new geometrical-model-based way of thinking in organizing city logistics by the use of cargo bikes. Although cargo bikes are popular in many countries particularly in Asia, their usage in European cities is not common. A new approach to managing city logistics is by clearly aiming to improve city sustainability. Within this paper, a model is provided to plan the location of cargo bikes within the capital of Hungary, i.e., Budapest. Figure 1: Overview of new trends and challenges within smart mobility (own source). Another contribution to the topic of city logistics is in the paper \"A Multi-Criteria Decision-Making Approach for Ideal Business Location Identification\" [8]. It searches for optimal placement of business within a city. This has a positive effect on the accessibility of activities, as discussed above, and can contribute, for example, to decreasing the number of miles traveled by vehicles, which is an important performance indicator. The paper focuses on the decision-making process and presents a hybrid of two techniques to solve the MCDM problem. The proposed approach is based on the AHP (Analytic Hierarchy Process) and TOPSIS (The Technique for Order of Preference by Similarity to Ideal Solution) approaches. The hybrid approach reduces the computational complexity and requires less manual effort, thus improving the efficiency and accuracy of the proposed approach. Given a set of candidate locations for a new business, the proposed approach ranks the candidates. Thus, the candidate locations with higher ranks are identified as suitable or ideal. Such a decision-making model has the potential to also be applied to other aspects of Smart Cities. The focus on citizens through services is also one of the key objectives mentioned above. This is true especially when looking at seamless integration of various travel modes. The paper \"Exploring Hybrid-Multimodal Routing to Improve User Experience in Urban Trips\" [9] introduces a new hybrid-multimodal routing algorithm that evaluates different routes that combine different transportation modes. Hybrid-multimodal routes are route options that might consist of more than one transportation mode. The motivation to use different transportation modes is to avoid unpleasant trip segments (e.g., traffic jams, long walks) by switching to another mode.