Smart pavement maintenance and infrastructure operation through digital twins : Case study for Norvik Port, Sweden

Abstract: There is an urgent need to make the way in which people and goods move more sustainable. Though pavements are one of the key components of road transportation networks and logistics systems, they are usually overlooked in systemic sustainability analyses. This means major downtimes for ad-hoc reparations and a general practice of higher resource and energy expenditure in critical transportation infrastructure, which in turn even leads to adverse consequences for actors in the transportation network. Though technological developments are rapidly advancing in the transport-, sensing-, and computational fields, such advances are rarely systemically implemented or exploited for infrastructure maintenance planning. Technologies that make the road itself 'smart' are still in a pilot- or project phase and are still generally underutilized on a larger scale. There is a significant risk that possible sustainability benefits on changes in the vehicle side (e.g., towards an autonomous or electrical vehicle fleet) are overshadowed by the continuous sustainability losses from the lack of changes on the infrastructure maintenance side. Pathways are therefore needed to show how such technologies can be embedded in the daily and long-term management of transport infrastructure to improve the sustainability of the entire transportation chain. For this reason, the ELISA project (Energy Effective Logistics and Infrastructure Systems Assessment for Cargo Port) started in 2019, with a focus on the recently built port of Norvik in the south of Stockholm for the development of a digital twin model. The project constituted a team of KTH researchers with different backgrounds that, together with stakeholders from the port, focused on developing and demonstrating how a digital twin of the port could be made as realistic as possible and thus contribute to the necessary paradigm shift. This thesis is one of the three research projects that were part of the ELISA project that, together, aimed to provide a systemic way forward for freight transportation systems on how enhanced digitization, automation, and sustainability of individual components and processes can lead to enhanced energy efficiency. In this thesis, the parts of the digital twin model that represent the actual physical geometries of the pavements, the characterization and the modeling of the mechanical pavement material properties and their degradation, the linking to the actual in-situ status of the pavements at the port as well as the coupling with the logistics model where developed. The aim of this thesis was thus to demonstrate that through the two-way coupling of the physical (pavement) and the virtual (operations) infrastructure of the port,  the twin model has the potential to support and guide sustainability improvements of the port's infrastructure system by decreasing overall resource and energy usage. To reach this aim, this thesis consists of three parts: the identification and critical evaluation of tools that could be part of the feedback loop of data from the physical object (the port) towards the digital twin, the building of the actual framework of the digital twin and the demonstration of its potential use:An important aspect of digital twins is that they enable a continuous interaction with the in-situ status of the physical object that is being modeled. Therefore, in the first stage of the thesis, some key components that could provide continuous pavement monitoring input from the Norvik port were explored. From this, more specifically, the feasibility of unmanned aerial vehicles (UAV) and a wide range of sensor technologies for reliable information acquisition at the port were evaluated.Focusing on a predictive approach and treating pavement distresses before they require large interventions makes it possible to enhance the system's sustainability as a whole. This required a computational model that could represent the geometry and material properties of the physical object (Norvik port). Therefore, pavement materials were collected from the port and tested in the laboratory for their mechanical properties and moisture susceptibility. The BIM information from the port's construction phase was updated with the details of the finalized pavement structures. A material model that could represent the visco-elasto-plastic nature of the asphaltic layers in the pavement was calibrated based on the lab data, and Finite Element models, representing the geometries and the material properties at the port, were developed for the sections of the port that were considered critical.The developed finite element model was coupled to the logistics model to form the digital twin of the port and enable demonstration of how the service life of the port's infrastructure can be affected by changing the port's operations and how the developed model could thus enhance the port's maintenance planning more holistically. Detailed scenario analyses were conducted for the three most important critical areas that demonstrate the digital twin's capabilities in extending the infrastructure's service life by connecting different systems typically viewed as independent.The use-case of the port had the benefit of being a semi-closed system with very well-developed logistics operations behind it. As ports generally are operations-based, downtime has very clear consequences for the economics of the facility and affects the transportation value chain immediately. Though the focus of this thesis is thus on the Norvik facility, the overall intention is to demonstrate that coupling of different parts of the transportation value chain is needed to enhance the overall sustainability of the transportation system and to demonstrate that the pavement, today merely seen a facilitator of mobility, should be given a more important part in this journey. With the advent of digitization within the transportation sector, it is therefore not an unlikely scenario that the ability to direct traffic with the focus on extending pavement lifetime will even become a likely scenario for more open transportation systems.