Very active "thru-train " switch towers.

[Overmod]

I don't think his link is quite complete, at least not on a criPhone.  See here and try different keywords (it won't let me type anything in)

http://web.mta.info/capitaldashboard/CPDSearch.html

I'm pretty sure he dropped three zeros.  The constant-tension cat conversion alone is many millions.

[BaltACD]

PATTBAA

The MTA states that Harold Ave. is "the busiest rail imterlocking in the (US).Harold Ave now is a MTA multi-year, $800,000 project.

new.mta.info|agency|construction-and-development

  

$800K sounds like yearly maintenance

[PATTBAA]

The MTA states that Harold Ave. is "the busiest rail imterlocking in the (US).Harold Ave now is a MTA multi-year, $800,000 project.

new.mta.info|agency|construction-and-development

[Overmod]

PATTBAA

The most direct route for freight and passenger traffic between New England and points West and South of Philadelphia was via the New York Connecting RR which "linked" the PRR / NHRR systems.

Something interesting to remember about this is that in all the early description of the NYCRR the 'main stem' is shown going to the Bay Ridge area (with the 'branch' being via Harold to the Sunnyside and New York Penn).  To me this always had the tinge of completing the tunnels under the Narrows to really optimize run-throughs of many kinds of train from the south and west...

It would be interesting to see precisely when this was changed to make the current "NEC" route the primary one and eliminate development of any fixed freight crossing south of Poughkeepsie.  

[CSSHEGEWISCH]

Another active tower was Kensington on the Illinois Central.  It controlled the South Shore's entry onto the electric lines and entry to IC's Blue Island branch.  Regular meets at 115th Street station between Matteson expresses and Blue Island locals were routine.  There was also fair amount of diesel freight and passenger trains passing through.

[PATTBAA]

I qualify the discussion subject with "thru-trains" to exclude switching procedures at stations and terminals. A very active tower during the WW2 years was the NHRR tower at New Rochelle because large volumes of the three types of traffic were routed thru the juction the tower controlled.The most direct route for freight and passenger traffic between New England and points West and South of Philidelphia was via the New York Connecting RR which "linked" the PRR / NHRR systems. Between the Bronx end of the NYCONNRR and New Rochelle was the  NHRR's 6-track Harlem River Branch; at the Queens end was a juction for passenger trains to Penn Station and freight trains to Bay Ridge on the Brooklyn water front which was the south end of the NHRR's electrified zone , the north end at New Haven. Also moving thru New Rochelle to Grand. Central was a large volume of commutor trains and inter-city passenger trains.Two very active PRR towers were "Zoo" and Harrisburg, Harrisburg now a museum with a very large interlocking machine which is an "operating exbibit".