ANS :Grade separated intersection design is the highest form of intersection treatment. This type of intersection cause least delay & hazard to the crossing traffic & in general in such superior to intersections at grade from the point of view of traffic safety . Advantage 1) Uninterrupted flow is possible for the crossing traffic. 2) There is increased safety for turning traffic. 3) There is overall increase in comfort & convenience. 4) It is possible to adopt grade separation for all likely angles &layout of intersecting roads. Disadvantage 1) It is very costly to provide complete grade separation & interchange facilities. 2) In flat or plain terrain grade separation may introduce undesirable crests and sags in the vertical alignment