To help rationalize structures such as inspection galleries installed inside dam bodies, an increasing number of dams are built using precast members for interior structures. It would be possible to lower the cost of making members if the design of inspection galleries were standardized and common forms used were established.

The Japan Dam Engineering Center has standardized inspection gallery design, and introduced a project in 1999 to rent out concrete forms for use in making precast members of inspection galleries. At 34 completed dams (as of 2011), dam body construction work has been rationalized by using precast forms developed by the Japan Dam Engineering Center.