Thursday, September 15, 2011

To Hybrid or not to Hybrid (buses that is)

Fresh off the assembly lineImage by paulkimo90 via Flickr
Hybrid buses...some transit companies have gone crazy having all new buses be hybrids while others such as TriMet in Portland and the Utah Transit Authority have been more conservative when it comes to buying hybrid buses. Back in 2002 TriMet received two New Flyer Hybrids while UTA received three of the same type of buses.

After evaluating TriMet made the decision not to order any new hybrids until this year because they did not see enough savings to justify the initial high costs of the buses. However, last year UTA received 10 Gillig Advantage BRT hybrid's to go along with a purchase of new regular diesels, and this year TriMet has decided to see how much the changes in hybrid technology in the last decade has changed and ordered 4 hybrids also from Gillig to evaluate their performance.

Some would argue that Hybrids use less fuel so transit agencies should by them. Of course life is a little more complicated than that. In fact the experience with hybrids have been a mixed bag largely because how well they save on diesel depends of the type of service they are used on.

New York is probably one of the biggest users of hybrid buses. In an environment like crowed New York streets were many of the buses are sitting in traffic or traveling at low speeds the hybrid technology pays off. However, in Seattle the opposite situation exists. Seattle purchased their hybrids to travel in their bus tunnel when it became a joint operation with Sound Transit Light Rail. However, once the buses leave the tunnel a number of them become express routes across the Seattle area. Because they spend a majority of their time travel at higher speeds Metro does not see the advantages of Hybrid technology.

Here is a article from Seattle about the performance of their hybrids from a few years ago:

Hybrid Buses Fuel economy promises didn't materialize 

Some later numbers may show some better performance from diesels including maintenance cost however lets look at some important numbers:

Currently Hybrid buses cost substantially more than standard diesel buses. For example TriMet's new hybrids cost approximately $650,000 while the new diesels that TriMet ordered this year coast about $400,000. So lets look at some examples to show what would make this purchase justify itself.

As you can see above the difference in price between the regular bus and the hybrid bus is $250,000. Let's say a standard bus gets 4 miles per gallon and a hybrid averages 5 miles per gallon. That means that you would save one mile per gallon. For the sake of this example and to make the numbers easier lets say that the transit agency will put 500,000 miles on it during its life at the agency. Also let's say that the average price of diesel during the life of the bus is $3.00 per gallon to keep the numbers easier. With this example the agency would spend $375,000 on fuel for a diesel bus and $300,000 for the hybrid.

The $75,000 savings does not justify the initial cost of they hybrid. In this example it is virtually impossible for the Hybrid to justify its initial cost. There is other factors that need to be considered beyond just fuel cost such as maintenance and resell value but that would most likely go in favor of diesel for maintenance and resell value is so small it is irrelevant anyway.

When making decisions on what type of bus to buy we need to look at hard numbers and not just try to feel good. But there is also something to be said for going beyond the bean counter numbers. Hybrid buses can offer other benefits that cannot be looked at on a balance sheet such as quieter operations and points on the political and public relations front.

On a profit and loss statement the hybrids may not add up, other factors may be in their favor but a transit agency needs to look at the the life of the vehicle and whether the substantial cost will pay off in the long run.
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Allie Cat said...

On the topic of Seattle, I thought the primary reason KC Metro bought hybrids for the bus tunnel was the transition from two-wire to one-wire power in order to accommodate Sound Transit's Link service. Formerly, the tunnel was full of dual-mode electric-diesel buses who pulled their power from an overhead wire, thus allowing the tunnel to be built with less provision for ventilation. With the overhead wire no longer being suited for buses, they had to buy some form of bus that could run electrically while in the tunnel.

custom trains said...

To buy or not to buy can be a difficult decision for many transit agencies when cost of equipment is already high and balance sheets are being highly scrutinized. Unfortunately, equipment such as buses lasts for many years and the needs of transit authorities and emission standards in the lifetimes of these buses may likely change. It is a tough decision for sure.

John Dornoff said...

@JN - Your right, I didn't want to go into the specific reasons for the purchase just that they purchased the buses for the tunnel. - thank you for your comments. Your right it is a difficult decision to make.

Anonymous said...

What's your source for the statement that hybrid buses don't save King County Metro money? My understanding from talking to people at the county is that the opposite is true.

It's also not the case that Metro solely bought the hybrids for tunnel service; rather, the buses for the tunnel have a modified hybrid drive with a special mode for tunnel use where the electric motor provides almost all the propulsion.

Your statement that most of the bus routes in Seattle's bus tunnel are expresses is misleading. Many of the route numbers are in the tunnel are for express routes, but most of the *trips* in the tunnel are all day routes that briefly run express before becoming locals agin, eg. routes 41, 71/2/3, 101/2/6, 150 and 255. The 550 is really the only all-day route whose duty cycle does not benefit from hybrid drive. Most of the other routes are peak-only commuter routes with less than a dozen trips a day.

What is true is that our regional transit agency, Sound Transit, sees no benefits from hybrid drives, because all of their routes are regional intercity expresses. They only buy hybrids because of federal grants that defray the additional cost.

Traffic in the dense urban core of Seattle, which much of Metro's service-hours are spent is as bad as any in NYC and compounded by extremely steep hills that shred conventional transmissions. It is a perfect environment for hybrids to shine economically, in addition to the quality of life improvement from not having something that sounds like a combine harvester drive past your office every five minutes.

To reiterate, I think you either need to correct this post or provide a citation for the statement that hybrids are not cheaper to operate in Seattle.

James said...

Here in Houston where air quality is an ongoing challenge, METRO has been buying hybrids exclusively for three or four years in part because the emissions are substantially lower.

John Dornoff said...

@James - That is where looking beyond the numbers come in. There are some areas where other factors trump over other economic considerations.

Research Essays said...

nice blog.I like your post about hybrid buses.i appreciate your ideas.It is a perfect environment for hybrids to shine economically, in addition to the quality of life improvement.thanks for sharing.

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