Truck Idling and Particulates

When I gave my job talk at USC, I discussed some of my research on how to get truckers to to shut off their engines. My colleagues have since told me they thought this was a dog of topic–it wasn’t a “big enough question”– but I made it entertaining so they hired me anyway based on the strength of my other work.

Well, it’s not a dog of a topic. Getting truckers and rail companies to shut off would alleviate PM2.5 hotspots in many locations, including parts of rust belt Pennsylvania. My friend Sacha sent this to me, as she found it at the American Academy of Sciences:

It was very much like Sacha to send me this little reminder that my work, though often treated like it’s uninteresting because it doesn’t have sexy, newspaper-ready sound bites, attempts to demonstrate how important seemingly small changes can be in the real-life environments that poor people occupy. Since my job talk, I’ve been somewhat embarrassed by the research on truck idling that we did–I’ve made excuses, etc–but forget that. I was right and the naysayers were wrong, and this work deserves more respect than it got.

Schweitzer, L., Brodrick, C-J, , and S. Spivey. 2008. “Truck Driver Environmental Attitudes and Behaviors: An Exploratory Analysis.”  Transportation Research Part D. 13 (3): 141-150.

Linsey Marr on the Discovery Channel: Women, Particles and Marathons

Linsey Marr, Associate Professor of Civil and Environmental Engineering, is one of many bright spots in my short career at Virginia Tech. She recently completed a study with Matthew Ely of the Army Research Institute of Environmental Medicine that was featured on the Discovery Channel. The study compared marathon performance in seven cities: Boston, New York, Chicago, Minneapolis/St. Paul, Sacramento, Los Angeles, and Duluth, MN.

The team found a significant relationship between lower performance and particulate pollution, but not between carbon monoxide, ozone, nitrogen dioxide, or sulfur dioxide. This was surprising for the researchers, but I don’t necessarily think so. If you think about most marathons or race situations, they clear out all the traffic and divert the parallel routes the whole way–which would move carbon monoxide away from the race route. Sacramento and Los Angeles have the worst ozone problems of these cities, but not necessarily on any given day; in Los Angeles, a marathon route on the west side would have the same ozone levels as Cedar Rapids IA (negligible); farther inland they would be higher but not necessarily at ground level, where runners breathe. So there may be a mismatch between monitor measures and what runners are actually taking in.

In any case, it’s an interesting study and a reminder of why I loved working with her so much and why I miss her so much now that I’ve left: asking interesting questions is the best part of our job.

Air quality, congestion, and pricing

One of my former students posted this story from the Wall Street Journal to Facebook yesterday. ARGH. Does the WSJ do no research in its reporting any more? So a time delay will shift drivers to transit but a charge for driving wouldn’t? Are WSJ reporters not required to understand basic econ anymore?

Congestion can be either good or bad for air quality depending on the geographic distribution of alternatives, the fleet, and the context into which the emissions enter. Congestion charging can in theory price trips onto the road under hypercongestion (the famous backward-bending demand curve), and thus may allow for greater VMT. But this is not true even in theory if the charging scheme is priced for VMT reduction or rationing rather than optimizing flow–those are different things, and the New York pricing plan was zone-based, so it most likely would have eliminated trips, not increased them! Higher throughput might affect emissions via flow optimization, but it is not apparent from either monitors or lab experiments that idling among a smaller number of cars/trips is objectively better for air quality than fast throughput from a larger number of cars/trips (and there may be a substitution effect in the traveling fleet that most people think is an air quality benefit; or there may be a freight effect which would not produce benefits [1]; we don’t know). Different types of emissions also vary with engine cycle, so it may be wash in total but a trade in emissions type.

Studies prior to the implementation of London’s cordon toll predicted fairly large reductions in emissions [2]. After the charge’s implementation, monitors throughout the metro area demonstrated significant and progressively distributed improvements in pollutant concentrations [3,4]. Now, it’s not likely that we can attribute all of that change to the cordon toll, as accompanying the toll were rapid increases in bus supply (so much so that train trips also went down concurrently following the implementation of the cordon toll; I suspect that congested trains were traded for less-congested buses for short trips, particularly after the transit bombings in July of 2005).

Traffic calming, transit-oriented, density-based efforts in Paris—without the concomitant tolling efforts that London put down—have been found to increase emissions substantially, so New York may not be doing itself any favors with unpriced congestion [5]. Concentrations in some congested areas, like San Francisco, have not been improving as quickly as in other places. It may be that these simply reflect that when air quality is generally good in high-growth areas, reductions occur marginally more slowly than in places where concentrations are comparatively high. (IOW, it’s hard to improve on good.) However, it can also be that worsening congestion has caused higher emissions and that is being reflected in some regional monitors.

Some of the smartest transportation people in the world are at New York universities, but why would we actually CALL THEM to get some ideas for this WSJ peice? For most of these people, it wouldn’t even a long-distance phone call for the WSJ reporter. See? Look at this list! This is a dream team of people to ask rather than just talking out of your backside. BAD WSJ.

But then, as my friend Chris Redfearn once noted, discussions like this require people to keep more than one idea in their heads at once. If we are throwing around the “dubious” term, congestion on transit–and this exists virtually everywhere in the world that isn’t in the US–is most definitely NOT good for the environment: see Mexico City, see virtually every Asian city over 10 million people, and the many scooter engines on the road rather than transit trips.

[1] Marr, L. C. and R. A. Harley. 2002. Modeling the effect of weekday-weekend differences in motor vehicle
emissions on photochemical air pollution in central california. Environmental Science and Technology, 36:4099–4106.

[2] Beevers, SD, Carslaw DC. The impact of congestion charging on vehicle emissions in London. Atmospheric Environment. 2005 Jan ;39(1):1-5.

[3] Atkinson R, Barratt B, Armstrong B, Anderson H, Beevers S, Mudway I, et al. The impact of the Congestion Charging Scheme on ambient air pollution concentrations in London [Internet]. Atmospheric Environment. In Press, Accepted.

[4] C, Beevers S, Armstrong B, Kelly F, Wilkinson P. Air pollution and mortality benefits of the London Congestion Charge: spatial and socioeconomic inequalities. Occup Environ Med. 2008 Sep 1;65(9):620-627.

[5] Bouf D, Hensher DA. The dark side of making transit irresistible: The example of France. Transport Policy. 2007 Nov;14(6):523-532.

Car-Free Downtowns: Green-ness and/or Economics or Both?

Kat Martindale sent me a link to this story about Sydney’s bid to take cars out of the CBD. Like the Times Square plan, this makes perfect sense from an economics standpoint: the land is too valuable to have space taken up through space-intensive modes like cars. Other very large, very congested cities who don’t regulate often go the same way through individual market sorting, with people taking to foot, bicycle, and scooter to slither through the cars sitting in gridlock.

Oddly, we may not know ultimately the environmental effect of these car-free zones. WHAT? ARE YOU STUPID, Dr. Schweitzer??? Anything that gets rid of cars is good, right? Well, we don’t know that these types of car-free zones actually get rid of cars and trucks, or whether the zones simply divert vehicles elsewhere, re-routing them and thus adding to VMT, idling, or just slower speeds–all of which can add emissions as easily as they can subtract them. Eliminating car trips isn’t as simple as disallowing them in various parts of the city. There will be local benefits to air quality and a bunch of other things, but we don’t know what happens for global or regional emissions.

There’s a nice manuscript, by researchers I respect immensely, on how Paris’ car suppression strategies have had mixed results for air quality:

Bouf, Dominique and David A. Hensher, The dark side of making transit irresistible: The example of France, Transport Policy, Volume 14, Issue 6, November 2007, Pages 523-532, ISSN 0967-070X, DOI: 10.1016/j.tranpol.2007.09.002.

Link in ScienceDirect.

Raised cancer incidence–EPA Air Toxics Report

Quite all over the news, as we would expect, are the EPA’s new raised cancer incidence maps from the National Air Toxics Assessment. Keep in mind these are modeled levels, not measurements.