The intervals that the cross current at the harbor entrance (0-kilometer position) exceeds the maximum are excluded from the safe time location diagram.
Cross current exclusion
At the 0-kilometer position (the harbor entrance) there is a sudden change in current. This can be dangerous when the cross current is very strong and the channel is narrow. This is prevented by an extra safety criterion that states that it is not allowed to pass the 0-kilometer point when the cross current is higher then a certain value (for instance 0.5 m/s).
Root finding algorithm with the cross current exclusion function
We are interested in the intervals that the cross current is higher then the criterion. By defining a cross current exclusion (continuous) function that excepts "time" as argument and simply checks if the cross current is higher or lower then the criterion, we have a function that can be used by
the root finding algorithm we also used for finding the safe time intervals.
Exclusion of the violated intervals
The result are intervals that should be excluded from the safe time location diagram. PROTIDE searches the safe time intervals at location 0 that overlap with any of the current exclusion intervals and then shortens, splits or removes the safe time interval. This exclusion physically changes the safe time intervals, thus results in white gaps at the 0-kilometer point. For extra insight in the solution these excluded intervals are added as an extra layer in red to the time location diagram.
