By splitting an oval into block sections it is possible to run a number of trains on the same line. The SA5-SB SA6-SB SA7-SB and SA8-SB each form a block section and can be combined together in any combination. To allow two trains on an oval at least three block sections are required, this is so that there is an empty block section for a train to move into, with four block sections one two or three trains could run.
This provides a passing loop for same direction trains with block control. The two points and the two 2 aspect signals are also controlled.
This provides a block section. If no train is in the next block section the train will run through non stop, however if a train is in the next block section the train will slow and wait until the next section is clear. The SA7-SB also operates a 2 aspect signal.
The SA8-SB is a block section with a station stop built in. If no train is in the next section the train entering the SA8-SB section will gradually slow wait at the station for a preset time then accelerate away into the next section. If the next block section is occupied then the train will wait at the station until the next block section is empty.