image creditTri-bridges are 3-way bridges on which traffic crosses two water streams or a body of water from 3 directions and one can travel from any direction to any direction. Because of their shape these bridges are generally called Y-bridges. However the tri-bridge at Hiroshima is referred as 'T' bridge because of its distinct 'T' shape.
It is also pertinent to note that many of those tri-bridges are just fork bridges wherein the traffic from one direction bifurcates in two directions or vice versa and there is no three way traffic.
(thanks Stanley)The Presurfer
