# Mobility, Citizens, Innovation and Technology in Digital and Smart Cities
## 3 Cities Transportation Trends
### Smart Parking  
Parks have played an important role in urban areas since they \"allow\" the access to other facilities. In urban congested cities, anybody can observe that parking his/her car somewhere may be as difficult as moving in the traffic jam because of the lack of parking places. The amount of time to find a place to park, known in the literature as the cruising time, can be huge. Like a domino effect, random cars riding in circles across the city hoping to get a parking place within walking distance and ease of parking (as well as previously parked locations) continue to contribute to inefficient time/energy spending, to congestion and to air pollution. For this and other facts, several initiatives are aimed at reducing the number of vehicles in urban centers, so-called carless cities. Recently, studies and cities policies have been analyzing impacts of several different strategies to reconcile parking and mobility, such as a reservation system for on-street parking [85]. IoT cloud-based intelligent car parking system was introduced by [PERSON] et al. [86]. In an attempt to develop a required system within a university campus, [PERSON] et al. [87] introduced a strategy using an info station based on decentralized autonomous agents sharing the data. Collective or specialized transportation is gaining momentum, as we highlighted in Section 3.1. At the same time, hybrid/electric vehicles can be idle for a fraction of the time. During these moments, smart parking arises [88] as a set of tools that can be connected with microgrid concepts, allowing vehicle batteries to interact with the power grid [89]. This represents a positive effect of such use, whereas a growing discussion has been pointing out these novel emerging vehicles systems as unsustainable due to their energy supply impacts [90; 91]. SC policies have also been discussing how to regulate and control noisy vehicles, for example, with surveillance systems [92]. The number of entities that are communicating in these new SC environments is impressive, which is another factor that motivates the study of distributed approaches, such as multi-agent systems [93]. Other alternative transportation systems, such as the use of traditional and electrical bicycles, scooters, hoverboards and skateboards, involve different parking logistic problems that must be solved by managers of a city or companies that operate in the sector. In an operational point of view, CI tools should try to find solutions that handle the following questions:  
1. Where is the parking located that makes it easier access to activities [87]? What size should they have? What are the transportation systems that this parking will cover? 2. How should these new operators (parking assistants) organize their routes to satisfy all demands at minimum costs? 3. How can the price be evaluated to charge customers for this service? 4. Is it better to have a flexible organization in which pickup and delivery of the cars may be done at any point, or a more rigid one where the pickup and delivery points are fixed stations similar to taxi ones (with the difference that, in this new station, cars will be picked instead of people)? Where can those parking assistant stations be located? * What is the system centered on? Citizens (target age, common local activities) or cost (greening techs and time savings)? Questions (i) and (ii) have their resolutions linked with facility location problems, including a non-standard variant of the TSP, which can be solved using exact methods or metaheuristics (as pointed out in Section 2.3). The question (iv) falls into the class of VRP (pickup and delivery) with the additional constraints between a pickup and a delivery point, associated with a demand, an agent should park the customer car somewhere. The pricing problems (question (iii)) can make the service attractive or not, as well as considering forecasting mechanisms that act in the market with information of energy consumption, generation and price [94].