# Experimental Research on the Load Transfer Mechanism of Tie Plates for 400 km/h High-Speed Turnouts
## 1 Introduction  
High-speed turnouts are an important part of high-speed railway tracks and are the key infrastructure that directly affects the smoothness and safety of vehicle operation. They integrate track structures, such as rails, fasteners, and turnout sleepers, and interface with power conversion equipment, track circuits, and other related equipment. As such, high-speed turnouts have complex systems and pose great technical difficulties. They are one of the core technologies of the high-speed railway in China [1; 2; 3]. Before China developed high-speed turnouts in 2005, only Germany, France, and Japan could independently design and produce high-speed turnouts for operation at speeds of300 km/h and more. The high-speed turnouts produced in Japan are compatible only with Japanese railways, as Japan has not realized real seamlessness of this technology. France's high-speed turnouts adopt ballastless track technology, Germany's high-speed turnouts adopt ballastless track technology, and they lead the world in the field of high-speed turnouts [4,5]. Since 2005, China has undertaken the independent research and development of high-speed railway turnouts. Through research and analysis, system design, structure comparison and selection, standard formulation, in-plant trial production, assembly and acceptance, trial laying and real vehicle testing, etc., China built an improved high-speed turnout technology system. China has completed the development of No. 18, No. 42, and No. 62 high-speed turnouts for operations at 250 and 350 km/h and holds the independent intellectual property rights for these turnouts [6,7]. As of this year, the high-speed railway turnouts of CN and CZ and passenger-dedicated lines have been in operation for more than 10 years. The operation assessment results show that the high-speed railway turnouts in China are in good condition overall. However, some problems, such as vehicle sway in the turnout area, the abnormal damage of rail parts, the wear of curved switch rails, the high failure rate of the conversion equipment, and the exceeding of the limits of turnout geometric parameters, are still encountered. The damaged or poor condition of turnouts affects the wheel-rail relationship, causing the wheel-rail dynamic interaction to become larger or even go over the limit as the train travels over the turnout, thus deteriorating the traveling smoothness and adversely affecting the operation speed [8, 9, 10, 11, 12, 13]. With the improvement of China's high-speed railway network and the progress in the high-speed railway technology, achieving higher operating speeds will be an important development direction for China's high-speed railway. In fact, China-standard Electric Multiple Units has been tested at 400 km/h in recent years. However, China lacks high-speed turnouts designed for 400 km/h operation, and indeed, they are rare worldwide. Developing high-speed railway turnouts for higher operation speed is not only of great importance to meet the needs of future high-speed railway construction but also a very urgent issue. In the design of high-speed turnout, a series of studies have been carried out. [PERSON] et al. [14] studied the geometric improvements in turnouts that permit high speeds over direct (350 km/h) and diverging (160 to 220 km/h) tracks. The improvements include transition curves, switch rail design, and mechanization that have been adopted to avoid the straight switch rail strike phenomenon. [PERSON] et al. [15] designed a gauge-widen switch of the No. 18 turnout based on Kinematic Gauge Optimization (KGO) and studied the impact of gauge-widen switch on the stability and security of train. [PERSON] et al. [16,17] established a dynamic design theory for high-speed railway turnout and made several creative designs. [PERSON] et al. [18] sought some new ways to improve the railway switches and crossings. [PERSON] et al. [19] studied the methods and parameters of the pass design of 60 AT2 high speed turnout rail.