### Instruction:

Extract the cause and effect entities from the following sentence:
Communications for shunting are particularly critical when a driver at the front of a train is pushing it backwards towards buffers or other potential obstructions

### Assistant:

KEYWORD: at
VARIABLE: the front of a train
CONDITION: other potential obstructions
EFFECT_1: Communications for shunting are particularly critical
OR: or
CAUSE_1: is pushing it backwards towards buffers
CAUSE_3: other potential obstructions
CAUSE_2: the front of a train


### END
