Nothing, however, is growing faster—or disrupting network velocity more dramatically—than the North American energy boom. In 2006, crude oil accounted for 3,000 carloads; an estimated 650,000 carloads will cart crude in 2014, according to the AAR.
"We've seen a big impact on our railroad from growth in the energy business, from frack sand to natural gas liquids to crude oil," Wick Moorman, chief executive of Norfolk Southern, told CNBC, following an earnings report that fell short of analyst expectations. "We've got a lot of infrastructure and a lot of work going on, but right now we just have a slower network and that affects every train on the network."
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That includes Amtrak. It's not surprising the passenger rail service is experiencing issues in Illinois. Chicago, where the eastern, western and Canadian networks converge, is the biggest, busiest and most congested rail hub in North America. It can take a freight train as long as two days to get across the city.
In October a new $140 million railroad overpass called the Englewood Flyover was officially opened to help mitigate some of that Chicago traffic, creating a bypass for passenger trains including Amtrak's.
Chokepoints like Chicago are the reason Canadian Pacific Railway recently approached CSX about the possibility of a North-East freight rail deal. Canadian Pacific had hoped to bypass the costly gridlock through consolidation. Such a deal has already been scrapped due to regulatory concerns, but not without the chief of Canada's second-biggest operator bluntly issuing a warning.
"We're quickly approaching a time where none of this works," stressed Canadian Pacific CEO Hunter Harrison, in a special investor call focused specifically on rail M&A. "We cannot continue to go down the road that we're going down and be successful and not have gridlock beyond anything we've experienced before."
Other operators including CSX, Union Pacific and Norfolk Southern have since argued that consolidation won't ease congestion, but instead cause at least short-term, increased delays in the form of merger-related service interruptions.
These companies say they're pouring billions into ordering more locomotives, training additional crews and developing better switchboard technology. The Class I railroads will invest $26 billion in capital expenditures and maintenance this year, according to AAR, a billion more than 2013. To a much smaller extent they are also adding more 'steel in the ground' to expand capacity for the approximately 50 percent of existing routes single-tracked throughout the U.S.
Industrial giants including General Electric have been developing applications to automate locomotives and better manage velocity. GE is testing technologies with operators like Norfolk Southern and Berkshire Hathaway's Burlington Northern Santa Fe Railway.
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"Toward the end of 2015, we would expect to see these service issues start to right themselves," said Citi's Wetherbee. "A merger could go a long way toward improving over the networks over the next three, four, five years, but in the short term we will see additional crews, additional locomotives trying to do all the work."
He noted that some companies have grappled with delays and service interruptions more than others. Norfolk Southern has suffered setbacks in recent quarters and BNSF has struggled most of the year, hit hard by the tough winter weather and its dominating rail exposure in North Dakota, another network pressure point where rocketing crude-by-rail demand has been causing weeks-long backlogs in grain shipments.
"It does take a while to respond to the market," said Ed Hamberger, CEO and president of AAR. "If you talked to anybody about North Dakota in 2009, no one would have predicted what we've seen."