Research methods: It is put forward what successful experiences and necessary lessons should be drawn from the survey，design and coordinating construction of existing railway for speed-raise through studying the information of foreign countries and the tested results of China.
Research conclusions: (1) The scale of investment and economic benefits depend on the quantity of main track and the minimum radius of curve.(2)Closing some stations of less passenger and freight traffic volumes during the innovation may save much operation cost.(3)Through doing dynamic load test } it can be decided whether the existing bridges needs reinforcement or not.(4)The midway between tracks of foreign countries and the test of trains meeting on Qingdao-Jinan Railway Line show the midway between tracks in China is relatively conservative.(5)Application of bandage technique for pier stand can avoid removal or reconstruction of existing bridge，or conducting transition engineering.
2007, Vol. 24 
