One little thing to be excited about going into 2021 at NYCT: it looks like the hegemony of diesel work locomotives is finally coming to an end.
In the NYC subway, we overwhelmingly use diesels to power work trains, as the third rail is switched off in work zones. The negative implications on passenger -- to say nothing of work train crew -- respiratory health should be self evident.
nydailynews.com/new-york/ny-me…
nydailynews.com/new-york/ny-me…
Though other systems (for example, London) have used battery locos for over a century, NYCT has historically resisted this, and has bought overwhelmingly diesel equipment until very recently.
But this July, a contract was approved for diesel-battery locos, whose electric traction capabilities will allow minimization of diesel time. It's not perfect, but this certainly should help pave the way for a literal clearing of the air. 
(I'd also be curious to know whether these electric traction locos would have higher power ratings than their diesel counterparts, as is true of comparably-sized locos on mainline railways. May help with the ever-present danger of work trains stalling out on steep uphills.)
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