Correct use of punctuation

Hello guys,

Please check below paragraphs in terms of correct use of punctuation, especially "comma". Notice that I want the sentence complexity remains the same without separating sentences into shorter sentences. I also want to know that is there any difficulty in understanding the meaning of sentences because of inappropriate use of punctuation? If so, where and what do you misunderstand? Thank you.

First of all, railway facilities are greener than road facilities. That is, trains carry more passengers and goods and burn fewer fossil fuels, which are a major contributor to global warming, than cars and trucks. Therefore, by improving and promoting railway systems, global warming can be reduced. 

Moreover, it is more affordable for policy makers to build more railway infrastructures than road facilities. That is to say, the development of railways mainly happens either under the ground level or in outskirts, while most street networks are developed within urban centers. This means that to develop streets, the demolition of residential areas is needed, so not only do governments need to pay the costs of knocking down the old built environment, but also they need to compensate for the costs of the demolished houses of the residents, while this is not the case for railways, which mostly are built in untouched areas.