Write an English letter according to the instructions given below in Chinese.

假定你所在的城市面临严重的交通问题。请从现象、原因及措施方面着手，以Traffic In Our City Needs Improvement 为题，写一篇不少120词的文章。

Traffic In Our City Needs Improvement

简述起重作业指挥手势信号的规定。