## 5 Future Developments on BIM-FM  
Although BIM was strongly linked to design phases in the beginning, multiple projects currently implement BIM as an outstanding tool for the infrastructure management through its lifecycle or even demolition stage [4; 8; 225; 226; 227]. BIM application in any project phase brings important improvements. Regarding the FM sector, BIM has been shown to be an important tool for the as-built data collection [4], maintenance and equipment control [8; 9; 23], quality control [25; 26], space and energy management [8; 28], planification [9; 228] or emergency protocols management [9]. Moreover, an early BIM implementation into the project design stage implies an important cost reduction due to the fault elimination, as it is detailed by [PERSON] et al. [151], eventually reaching 15% of the total project budget. Despite that, current social needs, especially on public infrastructure, demand an efficient workflow, especially in the infrastructure lifecycle management. BIM implementation barriers are more restrictive in FM sector instead of in design project phases. Concerning initial project stages, the main implementation barriers are the lack of standardisation [56; 58; 59; 60; 61; 62] as well as the interoperability [229] and powerful hardware needed. However, regarding BIM implementation into the FM sector, the main barrier is the lack of BIM skills [59; 62; 230; 231; 232]. This problem was found too at the design project stage. However, technical profiles are usually associated with initial stages rather than with the infrastructure management phase. Thus, it is quite common that the BIM information format is not provided to the final infrastructure users, which could be extremely useful to advance in the path of smart infrastructure. This framework details the tendency of the current society's needs, which demands digitalisation of the built environment. Considering BIM as one of the most outstanding tools to achieve the infrastructure digitalisation [148; 149; 150] is not enough. Increasingly, publications related to BIM add this methodology with new technologies such as IoT, Big Data or CC to achieve a total digitalisation of the infrastructure. [PERSON] and [PERSON] linked a BIM model with an occupancy sensor [233]. [PERSON] et al. developed an intelligent management platform for special COVID space management [234] and [PERSON] et al. reported an optimisation of the management techniques linking a monitoring system with a BIM model. While initial BIM publications detailed advantages of only BIM technology implementation, the current tendency points to including more technologies linked with BIM. There are even investigators who detail a complete digitalisation process of an existing infrastructure using BIM and developing its own management online platform. This fact details the direction of future investigations in the BIM-FM field. Projects linking BIM, preventive maintenance, IoT, Big Data or CC all in one are expected in the sector. Moreover, the loss of an important amount of BIM data format information is detected. Final infrastructure users do not normally realise BIM information utility due to its complexity. According to this, standardisation and final users' accessibility to BIM-based FM techniques are the future investigation routes in the BIM-FM field. Another line of research is the real-time interaction with the built environment [51]. This is the first step to achieve DT. The application of BIM with IoT, external DB, and DA by Big Data can automate the interactions between the physical and digital objects [50; 52]. These technologies appear in all types of infrastructures: in a more advanced way as in buildings or bridges and to a lesser degree as in linear infrastructures. The same applies to technologies linked to the capture of reality through UV, although here, new research is appearing that links GIS developments with BIM models in transport infrastructures due to their environment.