# Transition Effects in Bridge Structures and Their Possible Reduction Using Recycled Materials
## 5 Detailed Overview
### Engineering Aspect
Reinforcing the subsoil of the embankment and increasing its stiffness will reduce the transition effect. Implementing engineering structures combined with embankments on weak ground is a complex task. Evaluating the load-bearing capacity and stability of road or railway embankments is the initial step [69; 70; 71]. Structures embedded within the embankment are usually supported on piles in challenging conditions [23; 72; 73; 74]. Placing the structure on deep (pile) foundations results in minimal settlements [23], whereas allowable settlements for adjacent embankments can reach several dozen millimeters [69; 71; 72; 74; 75]. If the transition zone is not adequately designed or if the settlements are not uniform, unacceptable irregularities might emerge, which are also unacceptable to users. This aspect is more critical for railway lines [22; 69; 70]. Engineers often grapple with the durability issue of bridge structures. According to EC 0, bridges fall under category (class) S5, which implies an approximate design service life of at least 100 years. There are also structures over 200 years old that are still in use. Hence, the aspect of the durability and safety of the structure while limiting construction and operation costs is crucial [76]. The elements with the shortest lifespan in bridge structures are expansion joints and bearings. The most advanced ones can operate for only about 30 years [77]. While piers and girders determine a bridge's load-bearing capacity, equipment elements significantly influence its durability and maintenance costs. The immediate cost of equipment element installation constitutes around 15-20% of the bridge's construction costs. Their contribution to maintenance and repairs is often much higher, frequently exceeding 50% [17; 62; 76]. Ensuring the durability of bridge structures imposes specific requirements on the longevity of individual components. Despite advancements in bearing and expansion joint construction, production, assembly, and maintenance costs continue to rise. Additionally, there are increasing demands for the qualifications of personnel involved in these processes. The growing number of structures adds to maintenance challenges, highlighting the need for simpler solutions. Integral bridges present a viable option in this context. Frame structures, particularly integral bridges, are not equipped with these expensive solutions [40; 62; 77; 78; 79; 80; 81; 82; 83; 84]. Hence, they are less susceptible to natural and human-induced threats while requiring minimal maintenance throughout their service life. Most conventional bridges are equipped with components compensating for distortions and displacements. Water, salts, and other deicing agents can seep through expansion joints, leading to corrosion in bearings, load-bearing structures, sidewalk parapets, and other bridge elements. The absence of expansion joints in integral bridges reduces repair and maintenance costs throughout their service life [85; 86], aligning with the urgent global need for low-maintenance transportation infrastructure [87]. Furthermore, integral bridges, when integrated into highways or railway lines, enhance riding comfort due to the absence of expansion joints and provide better horizontal stiffness perpendicular to the longitudinal axis of the bridge. This reduces the likelihood of rail misalignment [85]. Moreover, modern integral bridges exhibit resilience during earthquakes owing to their monolithic construction [85; 86; 87; 88; 89; 90; 91; 92; 93]. Thanks to these advantages, such structures can be appealing to entities managing transportation infrastructure. These include single- or multi-span structures with a continuous deck connected to the abutment. The connection between the abutment and the deck can be rigid or semi-rigid, depending on the structural solution of the connection. The abutment can be articulated on the foundation or supported on piles.