介绍了美国、加拿大及墨西哥几个铁路公司对改造机车的看法和改造机车的现状及前景 ,指出改造后的机车将面临的环保问题。 This article introduced the views of several railroad companies in the United States, Canada and Mexico on the reconstruction of locomotives and the status quo and prospects of locomotives modification. It pointed out that the renovated locomotives would face the environmental problems.