Chicago's Tower 18 Junction at the corner of Lake and Wells was long billed as the world's busiest junction, and while I certainly can't vouch for that claim's accuracy, I can definitely tell you that it's still incredibly busy. This evening, my Dad and I took off to the Loop to shoot what we could of this junction, where CTA trains rolled through every minute or so. The tower is still manned, and this job will absolutely keep the operator on their toes.
This particular train is Pink Line train #314 running behind the CTA #5138 from 54th & Cermak.
Extensive info on this junction can be found here: http://www.chicago-l.org/operations/towers/tower18.html
An ongoing/growing album of photos that IMHO reveal the awesome, but seldom seen beauty of railroads because most of us don't go out after sundown or before sunrise. From dusk to dawn, lights are on! (And I continue to find new "Lights In The Night"!)