I have worked with range partitioning in sql server and Oracle. There are alter table statements to split and merge partitions.
I have not seen any clear documentaion in Teredata. I am interested in both RANGE_N and CASE_N how to be able to add and new paritions and may be merge.
Oracle (and SQLServer) implements partitions as dedicated storage ('segments' in Oracle). A table has diferent partitions, which are segments (sort of 'subtables', loosely speaking).
In Teradata this is completely different: it is about ordering the rows by the partitioning column(s) within the same storage. The seeking will avoid rows above and below the range desired based on this order. It has nothing to do with the Oracle 'partition pruning' mechanism, which will not scan the segments that are not needed.
You may re-read the Teradata documentation. It's not so bad iafter all... ;-)