## 3 Sustainability in Construction
### Linear Economy vs. Circular Economy  
In the 20 th century, the relationship of economic and social systems with the environment was called into question [56] because both Western countries and a sphere of influence of the USSR, participating in the conflict of civilizations, wanted to demonstrate their superiority in the effectiveness of the reconstruction of the world after the Second World War. Nothing mattered except productivity. There was no thought in terms of the entire life cycle. This approach must have resulted in economic problems, overproduction, and environmental problems. The latter was mainly because the \"take-make-dispose\" approach was the guiding principle in economies, especially in developing countries. The fashion had come to have new and better goods and abandon the old ones. Not everyone succumbed to it because poverty or scarcity forced other alternative actions such as the repairs, improvement, and reuse of old products.  
Construction and engineering, especially on a large scale, required the supply of freshly mined raw materials, newly manufactured materials, or semi-finished products. It was faster, more efficient, and the first thing that mattered was the final effect. Providing houses for people, building bridges, or other infrastructure all required large investments in a short time. A model based on a simple \"take-make-dispose\" relationship has been called \"linear economy\".  
It maintains the basic idea of abandoning all use of non-renewable resources [57] at the end of the product's life cycle. Today's production systems imply a serious challenge based on the change from a traditional linear economic model that creates products and releases waste to a new business production model followed by the transformation of the Circular Economy (CE).  
CE can be treated as a concept of reducing the ecological footprint by creating new flows of matter in manufacturing processes. It is necessary to abandon the traditional understanding of the product transformation process based on the \"take-make-dispose\" principle and replace it with a completely different understanding of the production system.  
In the construction sector, this shift is primarily about carrying out only these production processes that are featured by minimal waste and pollution. Thus, modern low-wastedesign solutions, energy-saving technologies, or environmentally friendly facility management become necessary for the effective implementation of CE. Moreover, a long-lasting circulation of products and construction materials in the whole production system is vital for its resilience. Therefore, decisions made during the design phase about the materials used for construction, the construction strategy (monolithic vs. prefabricated), and the types of joints (between different elements and parts of bridges) affect the efficiency of this flow in the subsequent project phases. The last pillar of the CE-based approach concentrates on care for nature. In the context of the construction sector, this must mean giving preference to biodegradable materials, materials of natural origin, as well as technologies imitating natural processes and solutions emulating natural systems [58].  
Unlike the linear economy, the Circular Economy (CE) has more advantages and manifests fewer negative externalities of business activity. The contemporary aspirations of European Union politicians aim to convert the paradigm of the so-called linear economy. Incorporating CE ideas into sustainable supply chain management provides several environmental benefits over a standard linear model [59].  
Decision making in bridge construction projects executed under the principles of sustainable development and the Circular Economy requires a lot of simulations, analysis, and certainly basic competencies (knowledge, skills, experience) to manage sustainable construction projects.