The double-stacking of many rail corridors which took place in the 1980s and 1990s allowed rail operators with additional capacity with essentially the same line infrastructures. As intermodal demand increased sharply in the late 1990s and early 2000s a substantial wave of investment took place over strategic segments of the American rail system with the goal of improving the capacity and efficiency of long distance corridors. The improvements are multiple, namely better grades, double (or triple) tracking, new and improved intermodal terminals, but also better signal and management systems. A particular effort has also been made to better connect the rail infrastructure with major port facilities, notably with on-dock and near-dock rail terminals. Both the capacity and speed of rail operations have been improved. The most significant projects include:
- Transcon corridor (BNSF): The most heavily used intermodal corridor in North America. $2 billion.
- Crescent corridor (NS): $2 billion. NS estimates that there may be up to one million truckloads that could be switched to rail along this corridor.
- Southeast corridor (CSX): $250 million.
- Heartland corridor (NS): $260 million.
- Meridian speedway (NS/KCS): $300 million.
- Mexico corridor (KCS): $NA.
- Sunset corridor (UP): $2 billion.
- Donner Pass corridor (UP): Improvement of a significant bottleneck across the Sierra Nevada to double-stack standards and longer train lengths.
- National corridor (CSX): $842 million. Construction began in 2009 and project expected to be completed in 2014.
- Asia Pacific Gateway and Corridor Initiative (CN/CP): Over $1 billion in various modal projects, with rail / road grade separation projects at key locations.
Mostly because of gradient, there are energy consumption differences between long distance corridors. For instance, the Prince Rupert – Chicago corridor established by CN in 2007 has a notable fuel efficiency advantage over other west coast long distance intermodal corridors. While the Prince Rupert – Chicago corridor is of longer distance, it consumes 5.2 gallons per ton of cargo moved, while the Seattle – Chicago and Los Angeles – Chicago corridors consume respectively 6.6 and 6.0 gallons per ton of cargo moved.