Comparative Study of Wheel-Rail Contact Impact Force for Jointed Rail and Continuous Welded Rail on Light-Rail Transit  
[PERSON]  
1 Department of Construction Engineering, Dongyang University, No. 145 Dongyangdae-ro, Pugggi-eup, Yeongju-si, Gyeongsangbuk-do 36040, Korea; [EMAIL_ADDRESS] (J.-Y.C. ); [EMAIL_ADDRESS] (J.-S.C.)  
[PERSON]  
2 Technical Director, SAM DONG LAND CO. LTD, 3 rd Floor, 23, Samseong-ro 96-gil, Gangnam-gu, Seoul 06167, Korea; [EMAIL_ADDRESS]  
[PERSON] and [PERSON]  
3 Department of Architectural Engineering, Gachon University, 1342 Seongnamdae, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea  
Correspondence: [EMAIL_ADDRESS]; Tel. : +82-031-750-4718323233233233233233233233233233233233233233233233233233233233233233233233233233233323323323332333233323332333333333333  
tracks, subsidiary main tracks, and side tracks often consist of multiple segments with sharp curves owing to a typical lack of available land in the city center. Figure 1 shows the typical damage of a rail joint connected to a joint plate without rail welding. As a typical mechanism of rail joint damage, misalignment occurs during train operation at the end of the two rails in contact with each other and manifests in the form of pressing and breakage in Figure 1. Rail joints are divided into suspended joints in which the rail joint is positioned between two sleepers and supported joints, which are positioned directly above the sleeper [1]. The upper photograph in Figure 1 shows a suspended joint and the lower photograph shows a supported joint. In the case of load in the area of the joint, the bending lines of both rails are not continuous, but form an angle [1]. The wheels have to overcome this angle and, therefore, exert an impact on the accepting rail [1]. This study measured the typical defects by rail joint type of supported joint. On the basis of this study, even for a vehicle base rather than a main track, we applied the design condition (impact factor) considering the rail joint impact in the design of rail joints for vehicle base installations, with the hope that the new research results for reinforcing rail joints can be applied in the field. The rail joint is a necessary component in track system. As the rail joints have low rigidity and strength compared with the rail centers, local settlement occurs. Further, the impact of a vehicle is generated to reduce the ride comfort and increase the maintenance. Damage can occur in the wheels and jointed rail ends when a train passes over discontinuity gaps in the rail joints, which can impact the rail, rail fastening system, sleeper, and even the ballast (Figure 1). This phenomenon represents a disadvantage of the entire track system as it easily subjects the trains to impacts or vibrations, reduces passenger comfort, and requires considerable manpower and expenditure for track and wheel maintenance [2]. In terms of rail joint types, most recent railways use continuous welded rails (CWRs), which comprise several long or short rails welded together. In conventional CWRs, fishplates are employed around the rail joint to connect the web of the adjacent rail by bolts, thereby removing the discontinuity gap in the jointed rail and significantly reducing impact and noise during train operation. Figure 1: Photograph of typical defects by rail joint type. (**a**) Suspended joint; (**b**) supported joint. A substantial amount of research both in Korea and abroad has focused on improving rail joints in order to mitigate rail joint impacts. Dynamic wheel-rail forces are generated when a vehicle is subjected to dynamic motions, primarily owing to track irregularities and changes in the track geometry. Geometrical track irregularities, unsprung and sprung masses of vehicle, track stiffness, damping variations in track flexibility, wheel flats, and corrugations on wheels and rails generate dynamic forces on the tracks [2; 3]. For example, [PERSON] et al.