## 11 Conclusions, Challenges and Future Research  
Urban interfaces lack user-centered design. In the majority of cases this serves to complicate the main objective for which they were originally designed and developed. This fact strengthens the hypothesis presented at the start of this paper. The proposed guidelines that were designed to evaluate user experiences of urban interfaces and tested in this study can also be used to evaluate any urban interface in the public or private sphere. However, other factors must be taken into account in order to consolidate the design of user-centered urban interfaces, and thus ensure the transition towards ever-smarter smart cities. [PERSON] [4] proposed six pillars for developing a framework for smart city development: Social, Management, Economic, Legal, Technology, and Sustainability (SMELTS). Usingthese pillars, it is possible to list a number of challenges regarding the evaluation of user experience on urban interfaces:  
_Challenge 1. Economic and legal variables._ On numerous occasions, the decision to purchase an urban interface revolves around whether or not there are available funds. However, the absence of a comprehensive assessment of an urban interface that includes guidelines such as those that have been described may incur hidden costs, including training, support staff, limited operating hours, and, in a worst case scenario, a shorter interface lifecycle. It is vital that evaluation instruments be included in the rules for public procurement and tender processes pertaining to urban interfaces to ensure that the design of said interfaces is suited to the target audience;  
_Challenge 2. Digital transformation of organizations._ Digital transformation involves changing several variables within an organization, one being the maturity of the user-centered design approach that is adopted. For innovation to be possible, validation mechanisms must be in place that are capable of ensuring that the digital products and services being offered meet the specific needs of the end user, thus allowing the user to complete any given task as efficiently and effectively as possible. Urban interfaces are no exception to the rule;  
_Challenge 3. Cultural, geographical and demographic variables._ As seen before, when implementing an urban interface, it is important to keep in mind the wide range of variables that exist in a community that influence how an urban interface may be used. This means that organizations should use similar instruments to those presented in this article to observe the behavior of people from different cultures, age groups, places of residence, etc. before deciding which interface to implement;  
_Challenge 4. Technology and technological innovation variables._ Innovative technology purchasing is not synonymous with alignment to user needs. In the case of urban interfaces, it is important to ensure that the technology complies with the user requirements, thus allowing them to complete their objectives as easily as possible. For the research team, the main challenges of this work have lain in the dissemination of said guidelines, and also in proposing a method that allows other organizations to evaluate urban interfaces. Given that the guidelines are designed and validated for the purpose of evaluating urban interfaces in a diverse range of settings, the guidelines and methodology can be replicated in other cities and applied to different urban interfaces. With the information contained herein, it is possible to make comparisons and reach conclusions regarding other possible scenarios. It is also possible to generate an evaluation index for urban interfaces across the globe to complement other indexes that assess the degree to which a city is transforming into a \"smart city\".