SINAL1 = (trocaamar -> amarelo -> troca1 -> verm1 -> trocaamar -> amarelo -> troca2 -> verde1 -> SINAL1).
SINAL2 = (trocaamar -> amarelo -> troca1 -> verde2 -> trocaamar -> amarelo -> troca2 -> verm2 -> SINAL2).

||SIST = (SINAL1 || SINAL2).