Capacity issues have a common cause - the government's (mainly federal, but states did their share of damage as well) meddling in this nation's transportation system in a lopsided fashion, i.e., the sinking of hundreds of billions of taxpayer dollars into highways and aviation, while simultaneously continuing to treat railroads as if they held a transport monopoly, heavily taxing their rights of way and terminal facililities, and forcing them to continue unprofitable services that in the majority of cases were rendered unprofitable by the very same lopsided transport policies. Only AFTER the government's policies succeeded in bankrupting half of the eastern rail network, and after much of the damage was done in terms of abandonment of rail capacity (in the name of "rationalization," in this case the abandonment of efficient transport, i.e., rail, in favor of government-subsidized highway and aviation transport, which would not have taken hold without the government's stupid lopsided policies), did the government finally act to restore some portion of balance (to the freight portion of the equation, mainly) through deregulation, taxpayer funding of repairs to the ruined northeast rail network (i.e., Conrail) and unloading of unprofitable passenger operations from the private rail carriers.
I recall not so long ago, during the (thank goodness) ill-fated SPSF merger talks/approval process, even Trains magazine parroting the stupid conventional wisdom of the time that the merger would allow "rationalization" of the two railroad's networks since the rail system was "overbuilt, even out west." I never believed the railroad network was seriously overbuilt (underutilized, maybe; overbuilt - no way). While there were perhaps some exceptions (i.e., CNJ/LV side-by-side into the Lehigh Gorge fighting for the same old anthracite coal traffic), the main trunk lines could have all been filled with traffic IF they survived until deregulation, reduced crews, and yes, the flood of international container traffic. Instead, due to the necessary (at the time) paring back of the system (because you pay taxes on your railroad whether you use it or not, while truckers don't have to fret over paying property taxes on the interstates, nor airlines on the airports, if they aren't using those facilities to capacity, nor need they fear the abandonment or reduction of capacity of such systems during periods of light use), now it will require more taxpayer money to rebuild capacity that in many places existed historically. There were other contributing factors, notably the rail union featherbedding, 100-mile "days" etc., but the background of infrastructure-provided-for-free competition was the gasoline making the fire.
Yes, we're also seeing capacity added that wasn't previously ripped out, but how many train photos do you look at that are single track lines that used to be two main tracks? Nothing makes me happier than to see 2nd (and even 3rd and 4th) tracks added to main lines in this country, but I wish our policies could have gotten intelligent in time to save other perfectly viable through routes (can anyone say Erie Lackawanna? Milwaukee Pacific Coast Extension?) before they became unfortunate victims to stupid, shortsighted government policy and stupid, shortsighted railroad labor unions' insistence on paid do-nothings riding on every train (and all of a crew's members getting paid a day's pay for a horse-and-buggy era's 100 miles traveled, even if it only took 2 hours to cover that distance).
GE, not EMD, makes the best locomotives now; has for over 30 years. Get over it.