Answer: to help the reader feel the excitement and unity of the striking workers.
Explanation: The quote expresses how organized was the movement in which the workers were involved: they had to behave in a rational and focused way in order for it to work properly, otherwise they would crash the strike. Also, by describing before the quote all the worker's actions in a very synchronized way shows unity and excitement for the unknown, especially when they see the policemen and don't know what to expect.