GR translation: with blue shadows to seal its passage

[Mike Jing]

I am going over Part 1 again from the beginning, making changes.  So
here are questions I was afraid to ask earlier.

P4.1-10   —they go in under archways, secret entrances of rotted
concrete that only looked like loops of an underpass . . . certain
trestles of blackened wood have moved slowly by overhead, and the
smells begun of coal from days far to the past, smells of naphtha
winters, of Sundays when no traffic came through, of the coral-like
and mysteriously vital growth, around the blind curves
and out the lonely spurs, a sour smell of rolling-stock absence, of
maturing rust, developing through those emptying days brilliant and
deep, especially at dawn, with blue shadows to seal its passage, to
try to bring events to Absolute Zero . . .

What is this "coral-like and mysteriously vital growth"?

What is "developing through those emptying days brilliant and deep"?
Is it the rust?  Why are the days "emptying", and yet "brilliant and
deep"?

"with blue shadows to seal its passage"  Whose passage?  And what is
trying to "bring events to Absolute Zero"?