Beijing-Tianjin Inter-city Railway Infrastructure Technology Upgrading Project involves the upgrading of multiple aspects, especially that of communication and signalling and power supply on the existing high speed railway, which has no precedent. In order to effectively support the infrastructure upgrading and reconstruction of Beijing-Tianjin Inter-city Railway, CHINA RAILWAY has initiated a systematic major project entitled "Infrastructure Status Assessment and Upgrading Technology Research of Beijing-Tianjin Inter-city Railway", which is led by China Railway Beijing Group Co., Ltd. with the participation of the China Academy of Railway Sciences Corporation Limited, Beijing-Tianjin Inter-city Railway Co., Ltd., China Railway Design Corporation, CRSC, and China Railway Liuyuan Group Co., Ltd. In order to upgrade and reconstruct the electrical and power supply devices, repair the defects of tracks, and study and establish the transportation organization mode of Beijing-Tianjin Inter-city Railway, this Project includes 7 subjects: 

Based on the study on the evaluation indicators of differential settlement and countermeasures under the operation conditions of Beijing-Tianjin Inter-city Railway, the study on key technologies for improving track regularity, and the study on the plan and profile parameters and evaluation methods, the recommended differential settlement and technical remediation measures were put forward for the safe use of bridges and track structures under the operation condition; the recommended static stiffness failure criteria for elastic base plate of fastener system, the detection methods and evaluation indicators for the bonding state of mortar layer of track slab were proposed; and the recommended slope section length, gradient algebraic difference, vertical curve radius, curve radius and other parameters required for fitting the plan and profile were given, as well as the fitted plan and profile of Beijing-Tianjin Inter-city Railway. 

Based on the adaptability study on 350km/h double pantograph operation of Beijing-Tianjin Inter-city Railway OCS system and the study on matching relationship between substation capacity of traction power supply system and current carrying capacity of OCS, the transformation scheme of traction power supply system and the overall technical scheme for upgrading and transforming the whole signal system of Beijing-Tianjin Inter-city Railway were put forward and implemented. Based on the study on the key technologies for the signal system reconstruction of Beijing-Tianjin Inter-city Railway, a complete set of technologies for upgrading and reconstruction of the signaling system for the same-time opening of C2 system and C3 system across the entire high speed railway in operation was developed. 

These achievements supported the upgrading and reconstruction of infrastructure such as track maintenance, communication and signaling and power supply and the construction of standard line for the Beijing-Tianjin Inter-city Railway. On August 8, Beijing-Tianjin Inter-city Railway resumed 350km/h operation, and the research results also provided useful experience for the upgrading and reconstruction of high speed railway in operation.