Why is passenger rail so damned inefficient?

[ This is about passenger rail, not freight rail, which is incredibly efficient. Freight rail is efficient because to reduce aerodynamic drag and diesel fuel use (USDOT 2008), they travel on average  only 23 miles per hour (to reduce aerodynamic drag), accelerate slowly, and stop very infrequently. The opposite is true of passenger rail: fast acceleration, fast speeds, frequent stops — all of these waste energy.

Although passenger trains should be shortened during the day to save energy since there are far fewer passengers, they seldom are.  This is because of the expense of union wages, the risk of problems and trains not available to meet the schedule, and/or a lack of side rails to rearrange trains on and store rail cars until rush hour.

Since studies were first done on the energy efficiency of different passenger modes starting in 1977 until the most recent studies today, buses are always significantly more energy efficient than trains. And they can be scaled up and down more easily, burn less fuel because they usually travel a shorter distance on roads than trains. The only reason trains are built is because the middle class thinks trains are classier than buses.  Well, get over it!

Alice Friedemann   www.energyskeptic.com  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts:  KunstlerCast 253, KunstlerCast278, Peak Prosperity]

NRC. 2015. Comparison of Passenger Rail Energy Consumption with competing modes. National Research Council, National cooperative rail research program, National Academies Press.

…”Decisions about train types and operating patterns in the passenger rail industry have not been strongly influenced by energy use and efficiency concerns. Instead, many technology and operations decisions have been motivated primarily by safety concerns, the ability to use proven equipment designs, initial implementation costs and the need to work within existing operating and infrastructure constraints.”

Although U.S. commuter rail ridership has grown over the past 15 years, energy efficiency on a passenger-mile basis has not improved. Yet technologies are available to improve passenger rail energy efficiency.

The high upfront capital cost of some energy efficiency upgrades is often much greater than funding available. So instead, agencies are more concerned on achieving a “state of good repair” (SOGR).

Tight budgets can lead to few spare locomotives. Taking them out of service for equipment overhauls and tune-ups is likely to lower service capacity or quality. But not maintaining them as recommended by the manufacturer or upgraded with energy saving technology leads to locomotives not running at optimal energy efficiency much of the time.

The uncertainty of what future funding levels will be can energy efficiency improvements by reducing the ability to plan future capital investments and make strategic plans.  This is made worse by  transportation funding authorizations getting shorter. In the 1990s rail operators had 6 years and since then it’s gone down to just 2 years.

Since locomotives can last over 30 years, and rail cars over 40 years, old equipment can reduce energy efficiency and increase costs for fuel for decades.

Another barrier is the internal accounting structure of passenger rail operators, which often doesn’t  incentivize departments or personnel to improve energy efficiency. For example, if the mechanical department purchases locomotives or energy efficiency upgrades, but the operational savings are received by the transportation department, there is no incentive for the mechanical department to improve locomotive energy efficiency.  If financial horizons are short-term, then the high upfront costs of a new locomotive will prevent one from being purchased, even if the long-term savings on fuel and operations would save money.

An individual train operator may not be incentivized to take energy-efficient actions because it’s impossible to measure fuel use with enough precision, so actions such as saving fuel by handling train-sets in a fuel-efficient manner or connecting train-sets to wayside hotel electric power for maintenance instead of idling the locomotive aren’t rewarded.

On the other hand, it’s pretty easy to notice and measure negative effects. If a train were late because of efforts to save energy, the negative impact on customer service of the train operator would be noticed. And unlike a car, a late train can affect hundreds of thousands of people.  So an individual is unlike to take risks to improve efficiency when there are no upside benefits and strong downside consequences.

It’s also risky to buy new technology before someone else has tried it (“service-proven”) in case it doesn’t function well enough.  It also might take a while before the energy efficiency improvement could be measured.

The lack of detailed data at a micro-level (e.g., trip-level) is another barrier to improving energy efficiency.  Data collection is hard, there is often no count of how many passengers boarded a train at a given stop, how much fuel was burned between stops (due to imprecise gauges on diesel equipment and inconsistent electricity metering And although electricity usage can be measured, it is not collected or recorded on an ongoing basis. As a result, it is difficult to provide feedback to locomotive engineers and maintenance staff or identify ways to reduce energy consumption on an ongoing basis.

Agencies are reluctant to divert funds from buying equipment to research and development to improve efficiency.

  1. 2.3 Conservatism and the Trade-off between Customer Service and Efficiency

The highest priority and key goal of passenger rail operators is customer service, followed by safety and security.  Energy efficiency is usually at the bottom of the list, though if ridership can be increased though good customer service, that will improve the energy efficiency per passenger-mile, though not the train miles per gallon, since passenger weight doesn’t affect overall train efficiency.

In the rare times when money to buy new rolling stock (locomotives, rail cars) is available, often the only choices are existing designs, and the cycle perpetuates itself, slowing the pace of innovation, and even resulting in no net change in energy efficiency.

There are many ways improving customer services reduce s energy efficiency

  1. Agencies operate equipment with the “pedal to the metal” to accelerate and go as fast as possible to improve travel time
  2. Trains that leave the platform early to minimize the number standing in the aisles
  3. More spacious seating
  4. Amenities such as Wi-Fi
  1. 2.4 Barriers to Improving Off-Peak/Backhaul Load Factors

Twice a day, during the morning and afternoon commuter rush, trains are likely to get pretty full and have higher passenger-mile efficiency.

But in many systems, the train passengers get off downtown and the train returns with few passengers to the suburb to pick up more passengers.  Only systems with layover areas or yards downtown can avoid this.

During the day, the passengers riding trains tends to be low, so ideally very short trains would run less often.

But often the same very long rush-hour trains run during the day, because labor costs are often 70% of expenditures, with energy only 10%.  That makes it too expensive to use labor to change train lengths between morning and evening rush hours.  Management also fears a malfunction during the coupling/uncoupling process which would prevent the train from running on schedule, especially since there are few spare locomotives and railcars. This is far more important to rail agencies than energy efficiency.

  1. 2.5 Market Size and Regulations Specific to North America

In the United States, very old, obsolete regulations force locomotives and rail cars to be far more heavy than trains elsewhere to withstand 800,000 pounds of pressure in a crash without permanently bending or buckling. In Europe, Australia, and Asia much lighter weight trains exist because they have a better way of designing passenger cars to withstand a crash.

This result is that U.S. transit agencies can’t purchase energy-efficient off-the-shelf trains which doubles their costs (Edmondson 2013).

  1. 2.6 Barriers to Implementing the Use of Alternative Fuels

Several of the respondents were asked if their company or agency were considering the use of alternative fuels to power their rolling stock. In the case of technologies that use liquefied natural gas (LNG) and fuel cells, respondents suggested that the major barrier to implementation is the limited availability of mature technology for passenger rail. One respondent suggested that the infrastructure requirements for fueling also represent a barrier, particularly for Amtrak, because its operations are nationwide and Amtrak does not own most of its infrastructure. Respondents mentioned successful Amtrak trials of a 20% biodiesel blend (B20) in 2010, but noted that the scope of this study was limited to assessing the impact of biodiesel on the diesel locomotive prime mover. These trials were facilitated by a $274,000 grant from FRA (Amtrak 2011). No subsequent tests were planned. A Volpe Center/FRA report highlighted some recent tests of alternative fuel locomotives (Brecher et al. 2014); however, few respondents were able to provide concrete examples of an alternative fuel that they are closely following, which suggests that the technology is not mature enough for implementation.

Electrification of infrastructure was the main “alternative fuel” discussed. Apart from the high capital cost, other barriers include electrical utilities wary of allowing energy from regenerative braking from locomotives back into the electrical grid; shared track with freight railroads poses a technical barrier since the high overhead clearance requirements for double-stack containers need a higher and longer, and freight rail doesn’t want to run both diesel and electric trains on the same track, or build a second track with overhead catenary, since that would reduce their flexibility.


Edmondson, D.  June 2013. Report: the FRA makes trains less safe, more expensive. vibrantbayarea.org

USDOT. 2008. TABLE 3-4-8 – Rail Freight Average Speeds, Revenue Ton-Miles, and Terminal Dwell Times. United States Department of Transportation.

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2 Responses to Why is passenger rail so damned inefficient?

  1. Weogo Reed says:


    In Europe a few decades ago I thought I saw locomotives and rolling stock that looked lighter than what we have in the US.

    I have wondered why passenger rail is so hamstrung in the US.

    How does light rail like the MBTA Green Line fit in this equation? :

    When comparing bus to rail, are road and rail maintenance costs considered?

    An interesting thread about light rail freight:

    As Paul Simon sang,
    “Get on the bus, Gus…”

    Thanks and good health, Weogo

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