Honolulu’s rail line will use more energy than buses or autos

article top
City's rail rendering

BY CLIFF SLATER – Our city government would like you to believe that the proposed Honolulu train would be energy- efficient, but this is almost certainly not true. The average modern urban rail line in America is less energy-efficient than the average automobile, as the following analysis will explain.

The following comments relate to the attached Appendix A, a five-page excerpt from the annual Transportation Energy Data Book, Edition 30, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, June 2011.


The comparisons made here conclude that Honolulu’s buses are more energy efficient than either automobiles or rail transit, and that even automobiles are more energy efficient than the Honolulu Rail project would be.

Highlighted on Appendix A-1 you will note that nationally automobiles use 3,538 Btus (British Thermal Units) per passenger mile (PPM), personal trucks and SUVs use 3,663 Btus PPM, and transit buses 4,242 Btus PPM, while rail transit only uses 2,594 Btus PPM (see table below). From this City officials would have you believe that rail transit is more energy efficient than autos or buses.

However, as always, the devil is in the details.

Rail transit energy use is not what it seems.

Appendix A-4 shows that a majority of the nation’s light rail lines use more energy per passenger mile than automobiles; only the twelve most efficient from Charlotte, North Carolina, to San Diego, California, perform better than the auto.

Appendix A-5 shows the energy usage for heavy rail systems, such as the Honolulu rail project.i This chart shows that two-thirds of these lines use more energy than automobiles. Note that New York’s rail transit system, which has a great deal of two-way traffic, uses less than 2,000 Btu PPM.

Note that the two lines most like the Honolulu’s project, in that they are nearly all elevated, are Miami and San Juan. Both of these rail lines are energy hogs, using 5,400 and 10,800 Btus PPM respectively.

The obvious question is how do these light and heavy rail examples shown square with the average rail transit usage of 2,594 Btu PPM shown in Appendix A-1?

The 2,594 Btu PPM number is a weightedii average and includes the New York rail systems which are not only highly energy efficient but also constitute two-thirds of the nation’s rail transit passenger miles.iii Thus, using a 2,000 weighted average and including New York leads us astray if we are looking for evidence of the likely energy efficiency of Honolulu’s projected rail transit line. We have to look at modern rail lines excluding New York if we are to review energy use that is are more likely to be like ours.

The average of heavy rail lines is 3,700 Btus PPM and given the heavy energy use of the elevated lines we believe it would be prudent to use at least 4,000.

Honolulu’s rail line would be a suburban oriented line. The highest use would be one-way into town in the morning, then returning almost empty, with the reverse pattern in the late afternoon. There would be light use during the middle of the day and in the evenings. This is not conducive to energy efficiency.

On the other hand, the big city heavy rail lines, especially New York City, carry a great deal of traffic in both directions and are still quite busy in the non-rush hours, which is the reason for their energy efficiency.

While the Final EIS makes blanket statements about rail being energy efficient and even gives energy usage data, it contains no evidence that it has done anything other than pull numbers out of the air. The only reference is to the Air Quality and Energy Use Technical Memorandum but that is no better in providing sources.

If the City had proof that its rail line would be more energy efficient the automobiles, their arguments would be well documented; they are not. The Final EIS has not justified any reason why the Honolulu rail project should be any more energy efficient than others in its reference class while intuitively, given the route’s projected operations, one should expect less energy efficiency.

How did we come to believe rail would be energy efficient?

In the 1970s, there were almost no light rail lines left since most cities had abandoned them in favor of buses.iv The only heavy rail lines in existence were the energy efficient ones in the densely populated cities like New York, Boston, Philadelphia and New Jersey. In addition, automobile usage then was 4,868 Btus PPM versus 3,538 today. One would be right at that time in believing that rail transit was more energy efficient than automobiles.

Our problem with thinking that rail transit is energy efficient is legacy thinking; we have not changed our thinking with the times and transit officials have not encouraged it.

TheBus is highly energy efficient.

While the average Btus PPM for buses nationally is over 4,000, TheBus averages 2,000 — half the energy usage of the average mainland bus system.

The Washington DC Cato Institute’s Randal O’Toole first noticed how energy efficient our bus system was. We checked his results using data from the National Transit Database and agreed with his calculations. See endnote for details.v

There is room for improvement. In Honolulu, for example, we have the same number of bus passengers that we had 20 years ago, 73 million annually, yet we have had a one-third increase in the number of buses and many of these are larger articulated buses. While we are presently highly efficient compared to the national average, there are bus systems that are close to experiencing energy usage of 1,000 Btus per passenger mile; it gives some indication that there are energy savings yet to be made for TheBus.

The relative inefficiency between rail transit and automobiles will widen in the future. Today’s transit energy use shows no sign of declining while automobile CAFE standards are to be increased 65 percent by 2025.vi

The growing use of electric cars will change matters because they can recharge their batteries at times when daily energy use is at its nadir. By 2030, the horizon year for the rail project, it seems fairly certain that automobiles being charged between midnight and 5:00 AM will do so in Hawai‘i through the use of wind power and ocean wave generated energy.vii Rail transit, however, sees nothing significant that will reduce its energy use in the future or its reliance, for the most part, on fossil fuels.






  1. The comparisons made here conclude that Honolulu’s buses are more energy efficient than either automobiles or rail transit, and that even automobiles are more energy efficient than the Honolulu Rail project would be.

Comments are closed.