# Transition Effects in Bridge Structures and Their Possible Reduction Using Recycled Materials
## 5 Detailed Overview
### Engineering Aspect
Very different design solutions for transition zones on railway lines are provided, but they do not include a comprehensive assessment of the transition effect [32; 57]. In contrast to roads where reinforced concrete transition slabs are frequently used, they are not popular for railway lines. Instead, the reinforcement of the embankment with geopolymers, draining and vibration-isolating mats, synthetic resins, stabilized soil blocks, gabions, reinforcements using stone columns or micropiles, dogging, chemical stabilization of sub-ballast, extending and widening substructures, and using stiffening rails within track rails are employed. Known solutions also include the compensatory injection method and polyurethane mass-stiffening aggregate. The use of substitute materials in the integral bridge engineering of embankments behind the abutment is often used to relieve this issue. By reducing the pressure on the abutment, its dimensions can be reduced, thus minimizing the difference in stiffness (compliance) between the surfaces. However, the resulting void between the back wall of the abutment and the embankment creates a discontinuity that can negatively impact operational qualities, increasing the transition effect. This type of solution has been studied, among others, by [PERSON] [61]. Engineers must therefore balance the selection of solutions to obtain a satisfactory effect. Road and railway embarments, as well as bridge abutments, can be designed as reinforced soil structures [21; 22]. Additional reinforcement at the bottom of the embankment, extending beyond the outline of the transition slab, is often used to minimize settlement differences [23]. The purpose of reinforcing the ground is to increase the soil shear strength and reduce the pressure on the abutment [62]. In such structures, active forces and external loads are partly transferred through friction by the soil and partly through the reinforcement anchored in the ground. Reinforced soil structures can particularly be applied as a soil block separated from the front and side walls of the abutment, bearing the embankment pressure, as a retaining structure forming the abutment walls and as a foundation support for piers. In the case of a significant increase in pressure on native soil, there is a risk of uneven settling or loss of stability. To reduce the differences between the embankment and abutment settlement in the transition zone, often, embankment soil reinforcement is necessary [21; 22; 23; 45; 63; 64; 65]. Using a reinforced platform allows for an even distribution of settling and can be controlled [66]. Reinforced soil structures, serving as retaining structures, can be executed using passive systems, where soil reinforcement comprises both structural elements (reinforcement wraps embedded within the reinforced soil block) and auxiliary components (anchoring inserts placed between the structural reinforcements), which anchor the protective elements of the wall. Alternatively, active systems incorporate reinforcing soil inserts anchored in the wall's protective elements (reinforcing-anchoring inserts). Simultaneously, protective elements functioning as formwork for subsequent layers of fill material are placed alongside the formation of the reinforced earth block. The protec  
Figure 4: Damage to road pavement (**a**) and rail permanent way (**b**) at the beginning of the transition zone where transition slabs are used. tive wall and reinforced soil block constitute separate structures, enabling their independent construction. For abutment elements, utilizing reinforced soil structures in a passive system is recommended due to the lesser impact of embankment settlements [63; 64; 65; 67; 68]. Flat steel strips, ribbed steel bars, polyethylene geogrids, polymer strips, or strips made of polyester fibers with a polyethylene coating serve as soil reinforcement. The reinforcement connects with the protective elements using systemic connectors. The use of geosynthetics in constructing transition zones holds significant potential.