In selection of waterstop, shall engineers use plain dumb-bell type or center-bulb type?

The plain dumb-bell type is used for joint location where small movements are anticipated. Therefore, construction joints are desirable locations of this type of waterstop. On the other hand, center-bulb type waterstop is suitable for expansion joints or locations where lateral and shear movements occur due to settlement or deflection.

All external construction joints in contact with soil/water shall have plain type and all internal construction joints the bulb type.