Early Warning Method and Model of Inland Ship Collision Risk Based on Coordinated Collision-Avoidance Actions
Table 1
Process of early warning method of inland ship collision risk based on coordinated collision-avoidance actions.
Distance to the closest point of approach (DCPA)
Time to the closest point of approach (TCPA)
Coordination degree for collision-avoidance actions of two ships (Co)
Early warning conclusion
DCPA > MinDCPA
TCPA > MinTCPA
Any value
When R is small, there is no collision risk
DCPA ≤ MinDCPA
TCPA > MinTCPA
Co∈[1, Co1]
A collision risk exists, but it is not yet imminent; an alert is issued that the two ships have not yet understood each other’s movements
Co∈[Co1, Co2]
A collision risk exists, but it is not yet imminent; the vessels have understood each other’s movements; an alert is issued that the vessels have not unified their collision-avoidance strategies
Co∈[Co2, Co3]
A collision risk exists, but it is not yet imminent; the vessels have understood each other’s movements and unified their collision-avoidance strategies; an alert is issued that the vessels have not yet taken coordinated maneuvering actions
0 < TCPA ≤ MinTCPA
Co∈[Co3, e]
The collision risk is imminent; the vessels have understood each other’s movements, unified their collision-avoidance strategies, and taken coordinated maneuvering actions; an alert is issued that the vessels have to verify the effectiveness of their collision-avoidance actions