Why commuter railroads won't run diesels
Earlier I talked about why
freight will never electrify their railroads. Now I'd like to show, by way of an example, why commuter railroads won't run diesels in the future, choosing instead to electrify their lines. There are a couple of reasons for this.
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More importantly, however, is the fact that electric trains accelerate much faster, and electric multiple units, compared to a diesel locomotive hauling several rail cars, accelerate like a bat out of hell. The
Fairmount DMU study gives the acceleration characteristics of a diesel push-pull train set such as MBTA and other commuter agencies use. Accelerating to 60 miles per hour takes 166 seconds; by extrapolation of the acceleration trend, 80 miles per hour would take 301 seconds. That's significantly slower than the Talent DMU that my last post featured, but look at it in comparison with a Stadler FLIRT:
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The FLIRT reaches 60 miles per hour in only 27 seconds, over two minutes faster than a traditional American train set and reaches 100 mile per hour in about 76 seconds, a minute and a half before our vaunted American train has hit 60 miles per hour (it's just about to hit 35 miles per hour). It also breaks significantly faster.
In this video we can see a deceleration from 70 kilometers per hour to 10 kilometers per hour in 9 seconds, which is an average braking rate of 6.67km/h/s or 4.145mphps.
This NTSB report on a Metrolink train exceeding a stop signal reports:
The third test used the service air brake and dynamic braking but did not use the emergency brake. The brakes were first applied when the train reached 74 mph. In this test, the brakes were applied in increments, as in the first test; however, there was less time between brake applications. The total stopping distance was about 2,490 feet.
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That, in a nutshell, is the advantage which electrification offers alongside fuel savings: a 33% reduction in travel time and making commuter rail operations truly time competitive with car travel. In this particular instance, the cost would be about $500 million or less for the electrification, plus the cost of train sets (
Hungary recently purchased four FLIRTs for 20 million euros), and much of the electrification cost can be covered through the California High Speed Rail program, making the burden more manageable on OCTA and the other Metrolink member agencies.
