Last months map of the month showed that NYC (CSX NY) and Pennsy (NS) had 4 track mainlines. Even with Centralised Traffic Control (CTC) the Northeastern mainline sare being taxed to the limit. CSX did complete a double track project from Willard OH To Chicago about 3 years back, What about a third main line between Cleveland and Albany and Cleveland and Harrisburg.
The three track mains are used for freight train capacity today. Union Pacific started triple tracking the Overland main line to handle the extra coal traffic. During the early thirties and forties last century when passenger trains were at their best, the two extra tracks were used by passenger trains to overtake freights and keep the schedules. The PRR and NYC ran so many passenger and mail trains each day that freight traffic would have always been on the siding waiting on the next varnish to go by.
Most two track main lines can handle 60 to 80 trains a day if operated correctly, but at some point, the third main is needed to add extra trains.
…CSX main line through our area here in central Indiana is double track…I note it’s signaled one way, each track…but see trains both ways on it at times. It’s former Conrail, ex. NYC from years ago. An east - west line.
It does not seem to have as much traffic on it as when Conrail operated it. Still a generous amount though.
Years ago it carried NYC Passenger trains too…A half dozen or so per day in my time. Each way.