This is a follow-on from an article where I meticulously compared various modes of transit in cost and energy use. I promised I’d get that done for a time series, and I’m ready to write about that.
First, Cost. The Cost per transit passenger trip is pretty simple to calculate, as we measure transit use in passenger trips, not miles. A passenger trip is far more useful than a vehicle mile, as a trip represents someone getting where they want, rather than just moving miles for the sake of moving miles.
I chose the maximum for this graph as the average cost of traffic trips in the US (~$2.06). We travel about half a light year in traffic every year, and the cost of owning and operating vehicles on our roads far exceeds the cost to government actually build and maintain the roads.
A lot of transit systems are more expensive per trip than traffic, which is why they are not shown here. There are no commuter rail modes (blue) shown on this graph, and Light Rail (brown) and Heavy Rail (green) are clustered here around the $1.50 price. The general upward trend in prices may be inflation. These values are not adjusted for inflation, but are a collection of annual reports strung together into a shambling wreck of data.
What you don’t see are the highest cost lines. The rouges gallery includes Connecticut Commuter rail, Dallas Area Rapid Transit Light Rail, and San Francisco BART. These agencies have been spending over $25 per passenger trip, which makes financing difficult at best.
With the same color code, as above, and repeating the same look at BTUs per-trip as a measure of energy. The colors are same.
The highest consumers of energy per trip are New Jersey Transit (Commuter Rail), New York Subway (Heavy Rail), and MBTA (Boston) (Light Rail). Each of these systems averages over 5x the per passenger energy consumption as a car in traffic. I’m pretty surprised by these number, considering that New York should be able to use economies of scale to improve their energy efficiency. They are also one of the most affordable systems, per person. NJ Transit is one of the largest Commuter Rail Systems, and MBTA operates the oldest, largest light rail system on the East Coast. It could be that NJ Transit’s great schedule service (short headways through much of the clock, over many miles of track) means that many of their trains run nowhere near capacity. A commuter rail train weighs dozens of tons, and even on the best rails it takes considerable energy to move the thing. It is not energy efficient to move transit vehicle when they are empty, but the schedule must be obeyed.
This is one reason schedules should be carefully balanced between potential and real customer service, and land uses should be concentrated around transit stations to ensure round-the-clock transit demands in both directions. If a large transit vehicle is going to be serving a place anyway, it is a waste to have it run empty.
One last thing: It is worth exploring what systems have high energy efficiency, if the high energy users are so surprising. Oddly, NJ Transit ranks well on energy efficiency for its light rail service. If I recall, that is just The Hudson-Bergen Line and the River Line, but there could be more. Northern Indiana, the one-time leader in interurban service, now has the most efficient commuter service. Finally, Staten Island Transit, also within New York City, has the most energy efficient heavy rail service. Curiouser and curiouser.
The energy use of electrically powered modes is not the same thing as the energy put into making the electricity, however. Though my earlier findings differed, the efficiency of burning coal, gas, oil, or protons to boil water to turn a turbine which turns a dynamo is listed in the transit literature as 40%. That is, we consume 60% of our energy on electricity just operating the machine to make the electricity, with only 40% of the energy output as useful electricity.
More on that later. Still wrangling my spreadsheet.
TS2.1TimeSeriesOpExpSvcMode TOS 2.xlsx