Chromatix wrote:
On the other hand, most European railways have moved to electric traction (with overhead wires and so on) instead of building ever bigger diesel locos. American railways are a weird outlier in that respect.
I see this sort of comment posted all the time by railroad enthusiasts outside of North America. It indicates to me that they don't understand the scope of North American railroad operations and the economy they support, or the economics of electric traction versus Diesel-electric traction.
Consider that the United States' conterminous land area is approximately 3.1 million square miles, roughly 79.5 percent of the land area of the entirety of Europe. Our freight railroads operate over about 140,000 route-miles of track and reach virtually every corner of that land area. In doing so, they must traverse terrain that varies widely in both topography and climate. As our population density is far lower than that of Europe's, most long-haul rail lines run through sparsely populated areas.
In Canada, the Canadian National and Canadian Pacific railways, the dominant freight carriers, operate a combined 32,900 route-miles and in equally challenging conditions (both also operate in the USA and some American lines operate in Canada). In fact, the Canadian Rockies pose one of the most difficult environments in the entire world for freight railroading, with huge amounts of snowfall in the winter, extremely cold temperatures and many heavy grades.
Distance, topography, climate, catenary power transmission limitations, and basic economics are the factors that explain why most North American rail lines are not electrified. Aside from the initial (and HUGE) capital expenditure required to install the catenary, its supporting structure, the power distribution network and, of course, the generating stations on routes that may stretch nearly 1500 continuous miles (for example, the BNSF route from Minneapolis to Seattle), there is the difficulty and expense associated with maintaining the infrastructure, especially in remote areas with weather extremes.
In addition to the above, North American freight train density is high on most mainlines, and the trains themselves are often very long and extremely heavy. Few European railroads operate trains that approach the lengths and weights that are routine here. For example, a typical train hauling coal from the Powder River Basin (located in southern Wyoming and northern Montana) may consist of 125 cars, each loaded with 100 tons of coal. The gross weight of such a train will be around 16,250 tons and will typically have a length of approximately 6,800 feet. On average, about 15,000 to 17,000 horsepower (11.2 to 12.7 megawatts) is required to start such a train and haul it at "track speed," which is typically 70 miles per hour on the long-haul mainlines. As train separation may be as short as 10 minutes on heavily-used routes, the loading on the catenary and distribution network would likely be impractical, were the line electrified.
Another issue is reliability and its effects on the ability of rail lines to operate. Electrification can be failure-prone due to extreme weather conditions that are often encountered in the winter. Lines come down due to ice formation, snow can infiltrate equipment enclosures and short out things, etc. On heavily-used lines, such as the aforementioned BNSF line, a catenary failure would be a major problem. Much of that route is single-tracked with passing tracks (sidings), which means if a train is stalled on the mainline due to catenary power loss, the entire line will become backed up for hundreds of miles in both directions. All it would take would be for one catenary substation to go off-line to stop everything.
Contrast that with operating with Diesel-electric power. Multiple Diesel-electric locomotives, in addition to producing power levels that are not usually attainable on an electrified line, offer redundancy. On level terrain, as long as at least one locomotive is operating normally, a train will likely be able to keep moving and get to where the dead unit(s) can be set out and replaced. A railroad doesn't have that option on an electrified line if catenary power fails.
Redundancy, along with the aforementioned costs of electrifying, is why we continue to use Diesel-electric power.
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However, during initial proof-testing the design I did haul a pretty long train, which also had several dead locomotives in the consist to add weight. We calculated the total train weight to be 7800 pounds, which is quite a bit to be hauled by a locomotive producing about 16 horsepower. The ruling grade at our railroad is 2.7 percent, so it got interesting as the train ascended the grade.
