Electric locomotives would save some money but deliver much less benefit than the “electric multiple units†(EMUs) that Caltrain has been planning to purchase, according to transit bloggers Alon Levy and Clem Tillier.
Given the risk to the $647 million in federal funding for Caltrain electrification, several readers ask whether electric locomotives would be a reasonable backup plan. Caltrain’s plan to electrify the line uses “electric multiple units†– rail cars that are each separately powered by overhead electric wires. Another way to electrify is to buy electric locomotives and to use them to haul the current set of cars.
This approach would save some money. Currently, Caltrain has budgeted $551 million for EMUs. Research by reader Michael Gimbel suggests that Caltrain would save about $400 Million by purchasing electric locomotives such as the Siemens ACS-64 “Sprinter.†However, according to Levy and Tillier the savings would be substantially less, because Caltrain would still needs to replace the over-30-year-old gallery cars that are nearing the end of their useful life. Replacing the gallery cars would cost about $200Million extra.
Meanwhile electric locomotives would have much less benefit. The main performance benefit of electrification is faster acceleration that lets the system reach more stops in the same or less time, which is especially useful in a heavily populated metro like the Bay Area, with stops every couple of miles.
While a Sprinter is pretty powerful and has good acceleration at medium speed, the acceleration is poor at low speeds, so they would provide only half of the time savings. To quote Alon Levy’s explanation:
“A EuroSprinter lugging 6 Bombardier BiLevel Coaches has a power-to-weight ratio of 16.5 kW/t (6-car KISS set: 20.3 kW/t maximum 13.5 continuous). But they are still crummy at low speeds, because maximum acceleration at low speed is limited by adhesion, which in turn is a function of the proportion of the load that is supported on powered axles. This proportion is somewhere in the 35-45% region for the KISS and 22% for a Sprinter pulling 6 BBCs. At 0.5 m/s^2 initial acceleration, the acceleration + deceleration penalty to 130 km/h is around 75 seconds; I don’t know what the KISS’s penalty is, but the FLIRT’s is 35, and the KISS is almost as powerful as the FLIRT. This is around half the travel time saving from electrification.â€
What is worse, by keeping the current unpowered car design, Caltrain would not be able migrate to level boarding, which lets passengers get on the train more quickly without stairs, faster for everyone, and more accessible for people with mobility challenges, luggage, and bikes. Level boarding will provide half again as much speed benefit as electric power with EMUs. Caltrain has been planning to migrate to level boarding with the new electric cars, by changing platforms over time.
So, electric locomotives would save Caltrain about $200Million, while providing only about a third of the benefit of electrification with EMUs, and locking in slower speeds and less accessibility for another 30 year replacement cycle.
Caltrain, the region, and the state would be better off finding backup funding to deliver the project in a way that would deliver the benefits including speed, level boarding, and service to the corridor station areas that are seeing transit-oriented development.
Update: here is more analysis by Clem Tillier showing why EMUs are best for the Caltrain corridor.
“With a 21-station stop schedule: a diesel locomotive will take one hour and 21 minutes to go end-to-end; with an electric locomotive, one hour and 14 minutes; with an EMU one hour and 10 minutes.â€
http://www.caltrain.com/Assets/__Agendas+and+Minutes/JPB/Board+of+Directors/Minutes/2008/9-4-08+JPB+Minutes.pdf
[…] A cheaper alternative, switching to electric locomotives, is no substitute for full electrification, which not only enables faster acceleration but is also essential for the transition to level boarding, notes Adina Levin at Green Caltrain. […]
Naive questions:
How about diesel multiple units? They would be similar to EMUs in terms of gripping the rails, no?
And what is the current state of the art in battery-powered EMUs? Could we expect them to be competitive in the next 5-10 years?
Battery-powered EMUs (BEMUs) are a viable, better, and much less expensive option for Caltrain electrification. Hitachi BEMUs are in revenue service in Japan. Bombardier field-tested BEMUs in the UK, and is under contract with the government of Germany to further develop BEMUs, with a prototype scheduled for 2018. BEMUs would eliminate the need for removing 1000 trees and trimming 3000 trees, raising the ceilings on existing tunnels, and disrupting Caltrain service while installing 50 miles of catenary wires. BEMUs would enable the extension of electrified Caltrain to Gilroy and someday across the Dumbarton route while avoiding obstacles of right-of-way ownership and construction costs. A BEMU solution, with a Tesla-like supercharging station, should cost about $700M, saving over $1B from the current $2B Caltrain electrification budget, and eliminating the need for the $647M federal grant. The BEMU approach would cause California HSR to terminate in San Jose – but that just means that passengers would simply cross the platform to a well-scheduled Caltrain express train to San Francisco, to a Caltrain local for Peninsula destinations, or to BART, VTA Light Rail or buses, which many passengers will do anyway. For a full analysis report of the BEMU approach, visit http://www.mikeforster.net.
Goal of electrification is increase service level and reduce operating cost. If we archive this goal, any method should be OK.
Which option can we increase more service under same operating cost?
We know EMU to Diesel difference of -11 minutes (SJ-SF, per Roland). Is anyone know the traveling time difference between non-Level and Level boarding?
If we can reduce traveling time for 10 minutes, we can add 5~6 more stops with same traveling time. Or, increase more train because of shorter end to end traveling time. Level boarding provide more accurate on-time performance. So, we can make tighter train schedule and shorter turn around time at terminal station.
If we don’t have enough money now, we should make leveling boarding as first priority. Then electrify and introduce EMU.
For the level boarding height, it should be 25 inch of Bombardia cars. Caltrain to negotiate with ACE to exchange their Bombardia car and Gallery car until certain period of time. Off peak and Weekend still use some Gallery car too.
Mike, Battery powered EMU is used branch line where electrification infrastructure cost is difficult to justfy but want to eliminate maintenance cost. (As most of JR are already electrified, maintain DMU require additional resource)
Caltrain is mainline and have enough traffic volume (30000+ rider/mile/day) which works better with traditional electrification.
In Japan, commuter line with traffic volume of more than 30000/km/day usually generate profit from operation.
I don’t have the expertise to evaluate the details, but one statement in Mike’s battery-powered EMU report certainly rings true:
“It would be unfortunate for Caltrain to be among the last light rail / suburban transit systems to implement an OCS / catenary-based transit system.”
Has Caltrain considered battery-powered EMU technology at any point? Given advancements in battery-powered vehicles of other types it seems foolish to ignore.
Mike & Karl,
Where do you expect these battery systems to charge? The examples you list are for cases where train runs under catenary and then switches to battery for last few miles of a branch line. With no OCS to begin with, signifiant charging will have to happen somewhere. Could you do it in 20 mins when train turns from SF to go back SJ? I don’t think so.
Also, the examples you give are single deck trains with lots of space for batteries below floors. There’s not much room in a double deck train and given that batteries are heavy, they can’t be mounted on the roof.
Another view:
Higher acceleration/braking is required for local train. EMU have absolute advantage over locomotives.
Question is Caltrain’s service road map after electrification. If they stick with “currently successful” skip-stop/Bullet pattern, there is not much benefit from EMU over locomotive.
I hope Caltrain to adopt BART like all-day frequent schedule, not just focus on bulk of ridership from commute hours.
BEMU tech is not mature and has not been demonstrated to scale to 8-car 500 ton trains doing frequent stop-and-go with sprints to 80+ mph.
It makes a nice toy for a branch line. I read the nicest Hitachi system can store 350 kWh (four Tesla cars). One Caltrain EMU will need about 100 kWh just to go between two stops. Even with regen, the round-trip efficiency is too low to enable a 15 or 20 stop schedule without recharging a BIG (heavy) battery.
BEMU is like the flying car. Just around the corner, and already demonstrated!
My analysis report may have an issue. I have removed it from my web site mike.forster.net for review.
I have updated my analysis report that still advocates that Caltrain pursue an independently-powered EMU approach, in this case powered by hydrogen fuel cells for range and supported by batteries to provide the acceleration of deceleration advantages of electrification.
By early 2018, Alstom Coradia iLint fuel cell plus battery carriages will enter revenue service on a 60-mile route in Germany, promising a range of 497 miles, and a speed of 87 mph. Other fuel cell EMUs are under development.
An independently-powered approach provides many implementation and operational advantages and should save $800M compared the currently-planned traditional overhead catenary wire system.
The full report, version 1.5, is available at mikeforster.net.