Do you think it is important to be able to see through the windows? Nearly all National Rail trains in service in Britain have double glazing, meaning that they don't steam up in cold or rainy weather. The only exception AFAIK are Pacers. Some trams don't have double glazing, such as the Greater Manchester T68s which steam up.
By contrast, most buses in the UK are single glazed, meaning that the windows steam up. Coaches have been double glazed since at least the 80s, though.
By contrast, most buses in the UK are single glazed, meaning that the windows steam up. Coaches have been double glazed since at least the 80s, though.