Tremendous water and soil burst accident happened on August 5th, 2007 at Yesanguan tunnel (L=13.8km) of Yichang～Wanzhou  railway. Three years ago, under the instruction of MOR, a conference on tunnel risk assessment inprecedented in Chinese railway history was held in Chengdu. In the conference, experts pointed out that water and soil burst is the most serious risks of Yesanguan tunnel. The accident proves that project risk assessment is of great necessity and that the risk management until  the end of the project should be raised.