Improving Environmental Efficiencies in Transit

» Transit’s environmental credibility depends on a switch away from carbon-based fuels — And a renewed sense that well-designed public transportation produces density.

Straight to the point: There are a panoply of choices to be made when investing in public transportation, but there is never an excuse for minimizing the negative environmental effects of a transit vehicle.

Some American public transportation agencies run bus fleets that consume on average a gasoline-equivalent 25 miles per gallon. This means — and this must be interpreted literally — that there are plenty of cars that, when driven from one point to another, are less carbon-intensive even with only one passenger than buses running the same route.

This fact is a disappointing one for transit advocates who would promote the idea that transit is, on face value, always more ecologically conscious than private transportation. It is a letdown to discover that the simple formula — more people in one vehicle = more fuel efficiency, thus public transportation > automobiles — doesn’t work out when those transit vehicles average fewer than 10 passengers at a time.

To the anti-transit zealots of the world like Wendell Cox, this fact is evidence that governments would be more likely to encourage decreases in carbon production by ridding cities of transit and instead pushing people into hybrids and other mildly polluting cars. That argument, however, completely ignores the fact that transit promotes communities that are denser, more walkable, and in general less energy consumptive — even if trains and buses sometimes feature lower fuel efficiencies than the newest Toyotas and Hondas.

To transit promoters like Jarrett Walker, this same information is indicative of the fact that transit planners must take to heart a variety of rationales when considering how to choose routes; the most ridership-heavy routes (those that would feature the highest average fuel efficiency) are not necessarily the most politically or regionally prioritized investments — which means that vehicles can often be found running with few passengers on board. Transit that runs all the time and to many places — and which therefore is frequently empty — is absolutely necessary to advance the kind of transit-dependent population that consumes less energy overall.

Nevertheless, the limited fuel efficiency of the fleets of many transit agencies is troubling because even if public transportation is effective in promoting better land uses, if buses and trains continue to spew pollutants, we’re not doing enough to address the underlying environmental consequences of transportation use. Indeed, while the adoption of hybrid-electric buses by many transit agencies is a step forward, the vehicles continue to emit carbon into the air — a problem that shouldn’t be side-stepped.

Full-scale electrification of bus routes and installation of catenary along train lines should be encouraged to further the environmental credentials of public transportation — as long as power providers increase the supply of renewables in the electricity mix. For cities, this clears the air as power is produced elsewhere (rather than in the vehicles, on the street). Overall, efficiencies are increased since centralized power production is more efficient than burning fuels vehicle-by-vehicle.

As automobiles become more and more efficient, buses and trains must be able to keep up — and the best way to do that is to go electric. To suggest that the poor fuel efficiencies of transit are merely a consequence of the realities of decision-making in the field is an attempt to make the issue go away, when in fact we should be addressing it straight-on.

27 Comments | Leave a Reply »
  • EngineerScotty

    One advantage that autos have over transit vehicles is a longer shelf life–transit agencies buy busses and trains and expect them to last decades. While conversion to a different energy technology may be feasible in some cases (changing from diesel to some other fuel, perhaps), if you are going to convert from diesel to electric you probably are better off buying a new bus.

  • Russell Warshay

    One advantage that autos have over transit vehicles is a longer shelf life–transit agencies buy busses and trains and expect them to last decades.

    Huh? Rail vehicles have considerably longer shelf lives than autos.

  • JP

    I’d like to see a comparison of the environmental impacts between electric buses, such as those in San Francisco, with standard Diesel buses. In addition to less pollution, I can attest that there are other advantages to electric buses: they are very quiet, they consume little energy during idle, and don’t spew exhaust directly into the street.

  • Yonah, what you say about trains and buses versus the newest hybrids is a false comparison. You should compare the newest hybrids to the newest hybrid buses and LRVs, not to the average ones.

  • EngineerScotty

    What I meant was that the average auto on the road is quite younger than the average bus, and younger still than the average train. It takes a long time to turn over the transit fleet.

    Of course, much of the “cars are more efficient than busses” line of attack is specious for numerous other reasons:

    1) It’s only true, and only marginally so, with busses running mostly empty most of the time. Jarrett points out that in many cases, busses running empty most of the time indicates the service exists for reasons other than green ones–but environmentalist critiques of social service transport are missing the point.

    2) More broadly, it’s an example of what I call the “monotonic fallacy”. This fallacy is the notion that if you want to get from point A to point B, where B is better than A in some way, that it is not acceptable for there to be any intermediate points worse than A. A widely used transit system, of which there are many in existence, is way more efficient than use of private autos; however building such a thing in one step is impractical. Cox’s argument is that since the intermediate steps (a transit network which is underutilizied due to low quality of service and extensive competition from the existing auto network) are “worse” than the status quo, that we shouldn’t bother.

    3) The analysis itself is faulty in several ways: Many such analyses fail to differentiate highway mileage from city mileage (just because your Camry gets 25MPG on the open road doesn’t mean its getting that in city traffic, which is where busses mostly operate), and assume a fleet of Prius’s or other fuel efficient vehicles (rather than the fleet we have), while comparing that to the existing bus fleet as opposed to a fleet of state-of-the-art vehicles.

    Certainly, as Yonah points out, there is much which can be done to improve the fuel efficiency and emissions of the existing transit fleet. One other thing I haven’t seen mentioned, is use of smaller vehicles on what Jarrett calls “coverage” routes. To pick once again on TriMet, it uses small busses for its paratransit service, but even its lowest-ridership regular routes get 40′ busses round the clock. Perhaps all of these routes need the larger capacity during peak hours (and certainly switching vehicles during the day would be a big source of inefficiency), but some of them, I would think, could suffice with a smaller and more fuel-efficient vehicle.

  • In addition, electrification would reduce noise pollution (my biggest personal pet peeve about buses) and provide an additional degree of fixed-route certainty to a bus route. I think this is one of the reasons buses are more popular in highly electrified cities like Seattle and San Francisco.

  • These kinds of arguments are easy to dispel by considering the marginal costs. Infrequent bus service is provided as a baseline social good. How much carbon are you causing to be emitted by choosing to take the diesel-guzzling bus? None.

    Okay, that’s not entirely true. It could be that you and others like you are riding that baseline service so much that it can’t handle the demand — so frequency is improved. So you could be causing more buses to be run, but this only happens if the buses are serving many riders on average.

    However, when you choose to drive your hybrid Hummer, or what have you, you’re directly burning the full amount of that gas. And probably on a longer route and for a more trivial purpose than if you were taking the bus.

    Should transit funds be used on making buses pollute less and use less fuel? To some extent, sure, but you have to consider that the fewer funds you have to spend on providing the quality of service that gets people to leave their cars at home, the worse the net result for the environment.

    Related point: Is it better to own a hybrid and drive it daily or use a car share gas-guzzler once a week?

  • EngineerScotty, the age issue isn’t much of an improvement for cars, since people don’t automatically buy the latest technology. Most people in the US aren’t buying hybrids – they’re buying gas-guzzlers that at best get 30 mpg, like the Accord, and at worst get 13, like any SUV. This is different from the behavior of transit and other government agencies, which switch to buying fuel-efficient alternatives very quickly.

  • Ocean Railroader

    Another possible factor in transit is the type of city it is running in such as the Old 1830′s City Core of Richmond vs say the other suburbs that were build in the 2000. The old city core struggles to deal with the massive flows of cars though it in that it was built with hourses and wagons, foot traffic and streetcars in mind and that a lot of it’s streets were not made care ready intill the 1930′s. So driving a car in it is odd in that it wasn’t really ment for it in mind. Trasit would be good here in that you don’t have to worry about parking and getting your car towed or broken into or getting hit.

    While if you took a streetcar or a bus into the other suburbs of Richmond it would feel very out of place in that it would drop you off in a place with no sidewalks to get to the bus stop or anywere else. In order for it to work it would have to have a big parking lot like the other places in the suburbs all have to help it take on the rules of the surburbs and live. Trasnit is onlly as good as the domain it works in.

    I noiced this after driving down some of the roads in the suburbs in Richmond that have bus stops along them and lot of the bus stops are in some very crazy places very few of them are near shopping malls or apartment complexs. In fact some of them say bus stop but there is a four foot deep dich behind you and it’s only two feet away from a flowing river of metal. In terms of safty it’s better to take a care in this part of the city. The bus stops in the city have seats to sit at and a good number of them drop you off along sidewalks.

  • Dave

    Also consider the impact of total trip time on fuel use and carbon emissions. A faster trip bus/HOV lane can still be better for the environment than moving the same number of people in autos which are stuck in creeping rush hour traffic, even if the bus is mostly empty.

  • An HOV/bus lane is useful mainly because of the fewer vehicles needed per number of people. The speeds have nothing to do with it – run buses at their full capacity, which is several times higher than this of a freeway lane, and they’ll crawl, too.

  • Wad

    J.D. Hammond wrote: I think this is one of the reasons buses are more popular in highly electrified cities like Seattle and San Francisco.

    The primary reason those cities use ETBs is because the buses can take steep hills very well. A diesel bus on a route like San Francisco Muni’s 24-Divisadero might end up rolling backwards even with full power.

    And like you said, ETBs are quiet. A little too quiet. In San Francisco, the ETBs emit a beeping noise like they were backing up.

  • In the paragraph about my position on this, Yonah writes:

    Transit that runs all the time and to many places — and which therefore is frequently empty — is absolutely necessary to advance the kind of transit-dependent population that consumes less energy overall.

    Actually, I make a distinction between empty buses that are part of an overall efficient pattern and those that aren’t. An example of the first is the last trip of the night on any route. It’s always empty but if you cut it, the previous one dies, because nobody wants to ride the last trip and risk being stranded if they miss it. More generally, it’s easy to argue that all the service on a route is part of the offering that determines the whole route’s ridership, even if some individual trips have few riders.

    I find it harder to infer a similar benefit from routes where the buses are nearly empty all the time (or all the time except for runs full of schoolkids at 8:00 and 3:00). If an entire route has low demand all the time, it’s usually because there’s usually not enough stuff on it that people are going to or coming from. And in that case, I contend that cutting the route, thereby raising ridership per unit of service systemwide, can be environmentally positive, especially if I add the service on a route where more people will use it.

    It’s certainly true if you’re going to sell the car, you need to know that you can get transit to neighborhood x if you ever want to go there. And if I cut all the service to neighborhood x because of low ridership, you’ll be mad at me if you know someone there. But the fact is, neighborhood x is not very dense, so there aren’t many people there, so not many people are going there, so the odds are, you aren’t going there much either. So I’m not sure that I do much harm to the cause of voluntary transit-dependency if I cut that route, especially if I reassign the service to be more frequency in a dense area that will value it.

  • Max Wyss

    It has been said that trolley buses do handle gradients way better than diesel buses. For one, the torque characteristics of an electric motor is much better at lower speeds (accelleration, uphills) than the one of an internal combustion engine. Also, an electric motor can be overloaded; the only limitation (assumed that there is no power shortage) is the maximum temperature in the armatures of the motor.

    Current trolleybuses do have quite a high instaled power, such as the Swisstrolley 3, available as single or double articulated, coming along with two traction motors rated at 160 kW (which corresponds roughly to some 400 hp)… and that’s all available for traction; the best I kind of remember seeing for diesel bus engines is in the 250 kW range … and that has to do it for everything (auxiliary components, air conditioning, compressors etc.).

    Of course, a trolley bus may create polluants … when the electric energy is created in fossil fuel power stations. However, one can assume that power stations operate at optimum performance, meaning that they produce the minimum possible CO2 and NOx for a given amount of energy, and it has been economically sound for quite a time to treat the flue gases if necessary… conclusion, a big power plant is cleaner than a local diesel engine for powering a bus … empty or full…

    One thing I have noticed during my visits to the US is that the drivers let their motors running when standing around. I don’t know how much fuel is burned uselessly when idling, but I could imagine that it may be up to 10 percent of the total fuel consumption. Something worthwile to look at, it seems to me.

    I don’t have the facts for it, so please correct me if I am totally wrong, but in comparision between Europe and north America, the quality of the north American (diesel) fuel is inferior. That might have an additional influence on efficiency, and definitely on flue gas composition.

  • Nikhil N

    This is an excellent analysis presented here. Living in DC, a drive from my apartment to the supermarket, less than 1 mile away, would be a fairly low-emissions trip. Things in the city are relatively close by, so trips are pretty short. But the fact is that this is possible only because the city is relatively dense and focused around decent transit. On the other hand, if you want to build a community where everyone drives to their destinations, then you have to build things at fairly low density in order to handle the volume of private cars, and all of a sudden that supermarket is 10 miles away, not 1. Auto-dependent communities thus require that much more driving. Not to mention the fact that suburbs where everyone drives to their destinations often remain extremely congested, no matter how low-density you build things.

  • Ernest B. Cohen PE & Ph.D.

    I would like o see taxes on the energy content of transportation fuels, for all modes. Fuel taxes are easy to collect at low cost. This would encourage use of more eficient modes, including a shift away from air for both people and goods, and more use of rail for both.Taxing the eneergy would also encourage electrification, which would increae the demand for nw power generation, hopefully from renewables and/or nuclear. Business as usual just won’t work anymore. The tax revnue can be use for transit and to elctrify the rail sysem.

  • Peter Smith

    Transit that runs all the time and to many places — and which therefore is frequently empty — is absolutely necessary to advance the kind of transit-dependent population that consumes less energy overall.

    I’m not exactly sure what this means, but two points:

    1) We should be looking to create places where people are not car-dependent, and also are not transit-dependent (i.e. we should be working to make sure that people are not dependent on any type of motorized transport).

    2) i don’t actually think it is true that we need to run empty transit cars all the time, if ever — at least, it doesn’t have to be true going forward — and if someone needs off-peak service, we may have to provide it in other ways — taxis, jitneys, car-sharing, bike-sharing, whatever — and it’s likely the person may have to pay more to use that service — i.e. there should be a disincentive. Decongestion pricing can do a lot. Better planning can do a lot.

    In my opinion, any system that is set up to waste resources in such an extravagant manner — like running empty transit vehicles — is a system that needs to cease operation — see 1) for more info.

  • Ocean Railroader

    Some of the car based suburbs can be very wastfull that it can be very funny some times how they are laid out. A lot of streets in the suburbs of Richmond are that you a house that’s only 1/4 a mile away from a store but the way the subdivsions and their dead end Cul de sacks are laid out you could easlly go 1 to 3 miles to go that 1/4 mile to get from one place or another. Sometimes you will even see two streets across a 20 foot empty grassy strip that you would have to drive two to three miles to get to from one subivsion to another. I think I would like to see some of the Cul de sacks opened up to tie into other streets like in the city of Richmond. The car traffic in the city of Richmond looks like it’s not funneled onto one main highway that’s jamed with cars like in the suburbs.

  • EngineerScotty

    A big component of modern suburb design, and one which is probably ill-conceived, consists of Trying To Get Traffic Out of the Neighborhood. Many suburban dwellers want streets with little traffic, and they way they accomplish this end is to make them dead-end, and channel through traffic onto the collectors and arterials.

    A second effect of this desire is the removal and segregation of commerce (the latter effect is no doubt aided and abetted by a “commerce is ugly, if not evil” ethic in some parts of the population)–many people seem to hold the view that living in proximity to business is inappropriate or substandard. I’m not sure where this view comes from–it seems to be a mixture of Victorian standards of propriety, and anti-corporatiism among some parts of the left–but it’s there.

    • Woody

      EngineerScotty, Racism is a large reason for, as you say, the “segregation” of commerce from suburban housing, IMHO. Many suburban developments in my old hometown and other cities in the former Confederacy are obviously trying to be gated communities without paying for the gates and guards. The aim is to keep out the riff-raff, especially the dark-skinned types. Of course, in commercial areas, dark-skinned people are present all the time, as employees and as customers. The bigots hope that by keeping “those people” away from their nice new homes and neighborhoods, they can maintain their lily-white lives. And looks like they succeed in that pretty well.

      So I find it amusing that you blame the tendency to separate and segregate housing from other community functions on some anti-corporatism among the left. Because then how do you account for it in places like Texas where there is no left to speak of, but there’s plenty of segregated and separated suburban housing?

  • ES: the separation of commercial and residential uses is much newer than the Victorian era. It comes from early 20th century modernist reformers, who viewed mixed-used neighborhoods as a mess. Proper order should consist of clearly defined separate spaces for living, working, and playing; since at the time industrial pollution was a major problem for neighborhoods, this seemed like common sense.

    It’s not anti-corporatism – the people who believed in this view were often patrician Progressives. In fact, in a recent example of separate-use zoning, Nissan forced Smyrna, Tennessee to zone the land it was going to build its factory on as industrial-only, on the grounds that commercial development would distract its workers.

    • Woody

      Perhaps the extreme example of this approach was Brasilia, a capital city planned by modernists in the mid-20th Century. It was constructed almost entirely of “towers in the park” housing districts. They are separated from the government (employment) district by a sprawling mess of wide boulevards that resemble limited-access freeways, with pedestrian crossings almost totally limited.

      But the city being in Brazil, the people who live there have been imposing their ideas of living onto the sterile framework, with kiosks and street vendors bringing life to empty sidewalks, and desire lines of pedestrian paths cutting thru vast open spaces designed to be left empty — it’s much like new vegetation breaking thru old concrete. And the outlying districts and suburbs, beyond the original city plan, are dense and lively.

  • Wad

    Alon Levy wrote:

    Nissan forced Smyrna, Tennessee to zone the land it was going to build its factory on as industrial-only, on the grounds that commercial development would distract its workers.

    It’s repeating the same behavior when Nissan was headquarted in Southern California. (It didn’t have an auto plant, though).

    Japan’s Big 3 automakers were within 3.5 miles of one another in the South Bay of Los Angeles.

    Honda and Toyota are practically next-door neighbors. Honda, though, has its headquarters across the street from Old Torrance, a streetcar-era walkable Main Street historic district. It’s more of a drive for Toyota workers, though.

    Nissan, on the other hand, was on the other side of the 110 freeway with nothing but a parking lot surrounding it. When Nissan vacated the space, the office real estate agent struggled to find a buyer because of the desolation of the HQ building.

  • I don’t think Nissan got to rewrite zoning laws in the South Bay. I think the main moral of the story of Nissan in Smyrna is less “Nissan is against mixed-use urbanism” and more “company towns are miserable places to live in because corporations have no problem engaging in government-style restrictions, without the usual democratic checks.” I mean, this is nothing the US didn’t see in the age of Pullman and Ford.

  • Wad

    You’re right, Alon, about the theme of a corporation going to a small town and basically controlling it with a choke chain.

    That’s one of the big reasons Nissan bailed on its California HQ. (A lot had to do with the South transplanting its way into prosperity, and Nissan did not have as many good years as did its former neighbors Honda and Toyota.)

    Yet, the fascinating thing is that Nissan chose to replicate its big, desolate California HQ and make an enormous, desolate HQ in Tennessee.

    I looked at Smyrna, TN in Bing’s bird’s-eye view, and that campus of Nissan’s has several housing subdivisions near it. I can’t say for sure whether those predated Nissan, but even if you were a worker that lived next door to the campus, you’d still need a car to cross the perimeter.

    Maybe Nissan is hard-up about corporate espionage. Honda and Toyota are also paranoid at their respective campuses. Yet that Nissan would embrace its desolation and grow it on a massive scale shows a reflection of its values and how it treats its employees and the community.

    Here’s a link to the aerial view of Nissan’s former Gardena HQ:
    http://tinyurl.com/ydaxht4

    Interestingly, Nissan’s neighbors include Metro’s Division 18 bus yard immediately to the southeast, and the Goodyear Blimp launching area to the southeast of that.

    Now for Smyrna:
    http://tinyurl.com/ye2hjwl

    I couldn’t even use Bird’s Eye at its most far out to capture the enormity of the Tennessee plant. You could fit whole college campuses on some of the larger parking lots there.

  • electric motors are great, they really help keep manual jobs easier;,-

  • I wonder which countries are really planning to invest in electric cars and charging stations.

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