What is the symbolism of the bus in the novel, One Day in December?

The bus serves as a symbol of life. It follows a constant routine every day, always moving forward, and unless you get off, you are always doing the same thing. The bus, in turn, provides opportunities to make changes. A person chooses when to get on the bus and off the bus, in the same way that they choose to speak to another person on the bus or to be silent.