Support BikePortland

Study: Separated bikeways mean better air quality for bikers, walkers

Posted by on October 28th, 2010 at 1:10 pm

Cycletrack on SW Broadway-4

Breathe easy in the cycle track.
(Photo © J. Maus)

An ongoing research project by the Department of Environmental Science at Portland State University is taking a closer look at how separated bicycle infrastructure (like cycle tracks) impacts the air quality and health of road users.

The goal of the research team was to determine the amount of ultrafine particulate matter from motor vehicle emissions that were inhaled by people riding on standard bike lanes (with cars directly adjacent) compared with people riding on cycle tracks (separated from moving cars, like the one on SW Broadway near PSU).

The grey box on the right shows the
parked car and the yellow diamonds
are where the P-trak instruments
were located.

Air quality levels were measured by ultrafine particle counters (known as P-trak instruments) that were attached to the rear-view mirrors of a car parked in the parking zone that separates the bikeway from the other traffic lanes on SW Broadway. With this set-up, exposure levels measured on the driver’s side were akin to what a person would be exposed to riding in a traditional bike lane and the exposure levels measured on the passenger side represented the exposure while riding in a cycle track.

The results show “statistically significant differences” in exposure levels and a correlation between those differences in exposure with traffic levels (which were also measured). The study concluded that the parked cars did not act as the main barrier to the ultrafine particulate matter and instead they found that lower levels were due to the “increased horizontal distance from the traffic stream.”

Image from research paper showing before (on left, with standard bike lane treatment) and after (with a curbside parking protected bike lane) conditions of SW Broadway.

Here are the key takeaways excerpted from the paper’s conclusion:

Cycletrack on SW Broadway-11

“Traffic measurements showed the exposure concentration differences to be greatest at times of highest traffic volumes, emphasizing the importance of mitigation techniques in areas with simultaneously high volumes of motor vehicle and bicycle commuters…

The findings of this study show a cycle track roadway design may be more protective for cyclists than a traditional bicycle lane in terms of lowering exposure concentrations of ultrafine particles… Based on these initial findings, understanding roadway and traffic effects on exposure levels can help guide bicycle facility design and pinpoint locations in which mitigation of exposure levels by placement of facilities such as cycle tracks may be most important.”

The paper, The Impact of Bicycle Characteristics on Bicyclists Exposure to Traffic-Related Particulate Matter, was accepted by the Transportation Research Board and is slated to be presented at their annual conference in Washington D.C. this January.

Authors of the paper were Christine M. Kendrick, Adam Moore, Ashley Haire, Alexander Bigazzi, Miguel Figliozzi, Christopher M. Monsere, and Linda George. The paper was funded the Miller Grant Foundation and the Oregon Transportation Research and Education Consortium (OTREC).

NOTE: We love your comments and work hard to ensure they are productive, considerate, and welcoming of all perspectives. Disagreements are encouraged, but only if done with tact and respect. If you see a mean or inappropriate comment, please contact us and we'll take a look at it right away. Also, if you comment frequently, please consider holding your thoughts so that others can step forward. Thank you — Jonathan

  • BURR October 28, 2010 at 1:28 pm

    all that fresh air won’t do you a bit of good when some trucker right hooks you in an intersection and you die.

    Here’s a recent example of a cyclist that was killed riding on a cycle track in Minneapolis exactly like the ones Portland wants to build:

    Recommended Thumb up 0

    • Jonathan Maus (Publisher/Editor) October 28, 2010 at 1:36 pm

      right on cue BURR!

      thanks for reminding everyone that engineers must use caution when designing cycle tracks because of increased dangers of crossing vehicles at intersections. These researchers made note of that in their conclusions, writing that their findings, “must be balanced against other consideration such as vehicle-bicycle conflicts at intersections and other design considerations.”

      You seem to think bike planners and engineers are oblivious to the added concerns that come about with cycle tracks at intersections. They are not (why do you think they chose the SW Broadway location and haven’t extended it yet!?). However, I think the experience of many cities and research shows that the benefits of separated bikeways — especially given the higher bike usage that results when they are installed — outweigh an increase in crashes. It’s also worth noting that right-hook crashes are not statistically the most severe types of crashes. They might be frequent, but they are more often minor injuries or close calls than fatalities.

      Recommended Thumb up 0

  • Spiffy October 28, 2010 at 1:31 pm

    seems like an obvious conclusion… the further away from car exhaust the better you are…

    now when will we see a national movement to redirect automobile exhaust pipes so that they don’t point to the right?

    Recommended Thumb up 0

  • BURR October 28, 2010 at 1:37 pm

    Here’s some video of the Minneapolis cycle track in action:

    Recommended Thumb up 0

  • BURR October 28, 2010 at 1:40 pm

    NYPD is now enforcing the mandatory sidepath law and ticketing cyclists who don’t use the bike lanes and cycle tracks:

    Recommended Thumb up 0

  • BURR October 28, 2010 at 1:41 pm

    @ #3 good job cheerleading for these unsafe facilities, Jonathan.

    Recommended Thumb up 0

  • Jonathan Maus (Publisher/Editor) October 28, 2010 at 1:53 pm


    1) I’m not cheerleading for anything… just trying to answer some of your claims.

    2) i don’t agree with you that these facilities are “unsafe” in and of themselves. What I do feel is unsafe is an adherence to a status quo that has lead to abysmal rates of bicycling in America.

    I’m totally open to whatever solutions will be best to move bicycling forward. What’s your solution? Besides bashing everything PBOT does on every story when I mention them?

    I think the solution of “Everyone should just learn how to ride with traffic and we don’t need bike lanes or separate bikeways” is just ridiculous. Yes, we need people to learn how to ride more comfortably in traffic and yes taking the lane and being “vehicular” when you ride is awesome and I do it all the time… but we must do something different.

    The fact is that America sucks at getting large amounts of people on bikes. Many in the planning/engineering profession right now think the way to not suck as much is to try more separated facilities similar to what is done in Europe — where people of all ages and abilities ride safely and comfortably in huge numbers. Is this the wrong approach? That might be open to debate, but I think it’s clear we should at least be experimenting (which we are), because the status quo in America in terms of bike engineering simply has not worked for anyone but less than 1% of the population.

    What are your big idea to make bicycling work better in American cities (besides improved adult education and a reform of licensing laws/test for drivers).?

    Recommended Thumb up 0

  • jim October 28, 2010 at 1:59 pm

    How come in the top photo there is no center line in the bike path? Won’t they have a tendency to hit each other head on with no lines to show them where their lane boundaries are? There are no arrows painted on the ground to show them which way to go either.

    Recommended Thumb up 0

  • jim October 28, 2010 at 2:05 pm

    Reading Burrs post brings up a valid point. With this type of a set-up it will be very much like having a bike ride out into an intersection from a sidewalk (very illegal and dangerous)
    How on earth do you expect a car to see you coming out from behind parked cars? I can see a lot of ghost bikes tied up on those corners

    Recommended Thumb up 0

  • jim October 28, 2010 at 2:07 pm

    I meant to say- how do you expect to see a bike coming from behind the cars? (from the drivers viewpoint)

    Recommended Thumb up 0

  • Jonathan Maus (Publisher/Editor) October 28, 2010 at 2:10 pm


    BURR does indeed have valid points. He’s a smart guy and that’s why I listen and respond to him. Cycle tracks present new challenges for design/engineering. My point is that those challenges can be met and when all is said and done we will have a more complete and safe bike system that can be used by many more people than are using it now.

    Recommended Thumb up 0

  • G. Tyler October 28, 2010 at 2:17 pm

    Why can’t they make it so you can’t park cars within 30′ of an intersection? That would make a nice window for drivers and bicyclists to see each other. I never understood why Portland allows vehicle parking right up to stop signs at intersections, it isn’t allowed in Seattle leaving better visibility.

    Recommended Thumb up 1

  • BURR October 28, 2010 at 2:31 pm

    btw, I really like the way you downgraded the right hook from ‘a serious problem’ to ‘no big deal’. That was slick.


    Recommended Thumb up 0

  • q`Tzal October 28, 2010 at 2:39 pm

    Remove the last 30 feet of auto parking adjacent to an intersection.
    Rather than leave it empty and encourage cars to use it, and by extension of mass, and the cycle track as a right turn lane, install on-street bike parking corrals.
    On-street bike parking corrals just prior to a turn solves two problems: it provides ubiquitous cycle parking and provides a clear sight line for auto drivers of cyclist. Bike parking corrals at each corner would also serve as a very big reminder that the cyclists belong there and you can expect them. The road side of the corral could easily have a sign reminding auto drivers that they do indeed have to yield to cyclists.

    Recommended Thumb up 0

  • El Biciclero October 28, 2010 at 2:39 pm

    Hybrid vehicles or fewer motor vehicles also mean better air quality for cyclists…

    Regarding implementation of cycle tracks, I really do appreciate that there are people out there trying to think up ways to make cycling appeal to the broader population. The problem with any such facility, however, is that it cannot usually be made “safe” without one of two (or possibly more that I haven’t thought of) things happening in parallel with their implementation:

    1. Treating cyclists like pedestrians (e.g., put them on MUPs, give them separate signals, shuffle them up and down onto/off of the sidewalk, etc.), which, IMO, reduces the convenience/efficiency/safety of cycling for transportation.

    2. BURR’s chorus of re-educating drivers and cyclists and/or enforcing laws related to bicycle operation on the roadways (separated or not). I daresay that Europe’s separated bikeways would not work very well at all without the education and cooperation of drivers, cyclists, and law enforcement. I’ve never been to Amsterdam or Copenhagen (disclaimer), but everyone I’ve ever heard talk about it remarks on this point: “the facilities are great–and the drivers all understand and make allowances for bikes”. There are usually also mentions of laws that put the onus on drivers not to run over people.

    The root problem is not facilities. The root problem is OPERATORS. Building “better” facilities is like putting drivers in a rubber room–it doesn’t teach them anything. Facilities do not address the real problem. The American attitude toward roadway use and traffic operation is backwards, upside-down, and b0rK3n. “Better” facilities are merely compensation for this deficiency in our collective psychology.

    The problem with “experimenting” is that the subjects of the experiment often don’t realize that they are participating in something unproven and are lured into dangerous situations unawares. In all the years engineers have been thinking about this, are there zero proven designs for bike facilities that work better than others? If that is the case, then are we sure it’s just a matter of designing “better” facilities? Or, do we also have to consider, as BURR continues to remind us, that education and attitude play a very large role in any effort to make cycling conditions better?

    Recommended Thumb up 0

  • BURR October 28, 2010 at 2:40 pm

    I think the solution of “Everyone should just learn how to ride with traffic and we don’t need bike lanes or separate bikeways” is just ridiculous. Yes, we need people to learn how to ride more comfortably in traffic and yes taking the lane and being “vehicular” when you ride is awesome and I do it all the time… but we must do something different.

    Thanks for mischaracterizing and marginalizing my position once again, Jonathan.

    I have never once said that I am against bicycle facilities, nor have I ever claimed to be a dogmatic ‘vehicular cyclist’.

    I have repeatedly made it clear here that my objections to these separated cycle tracks is based on their inherently unsafe design, and for the record I have repeatedly proposed solutions based on the use of sharrows on arterial streets, wider conventional bike lanes, and development of true separated paths along rivers and other geographic corridors where there is not a potentially hazardous and fatal intersection every few hundred yards.

    I’d appreciate it if you’d please stop mischaracterizing my position on cycling infrastructure.

    Recommended Thumb up 0

  • BURR October 28, 2010 at 2:45 pm

    And by the way, I’m also a big fan of true ‘destination positioning’, which means that you don’t put a through bike facility of any type to the right of right turning motorists. Ever.

    Recommended Thumb up 0

  • Jonathan Maus (Publisher/Editor) October 28, 2010 at 2:45 pm


    Thanks for the response. Glad to be reminded of your solutions and I apologize for mischaracterizing your positions. I was sort of lumping you in with some general annoyances I have and that’s never a good thing to do, nor is it fair (when I’m typing all day and mind in a million places I am not as careful or sensitive as I should be)..

    I love your solutions and agree with them… I think your comments would have much more impact if you’d just lay them out the way you’ve done them in your recent comment instead of the way you did in your first few comments on this thread.

    My goal is to have a productive discussion about the issues and have all opinions given the chance to be heard. If we do that, the best solutions have a chance to rise to the top.

    Thanks again for clarifying your positions.

    Recommended Thumb up 0

  • David October 28, 2010 at 2:47 pm

    When I saw the title of this post, I assumed it was about the effects of separated bikeways on air quality. Silly me! Thanks for clarifying in the comments section that this piece is actually about the impacts of separated bikeways on bicycle collisions. Carry on.

    thanks for the sarcasm David.

    I get frustrated when the comments don’t reflect the content of the story … but I’m not about to delete/censor them and when I feel the comments that do arise warrant attention, I will try to join them and see if we can’t get to some great understanding or resolution.

    But that being said… FWIW folks, I think people interested in the science of this story are scared away by the back and forth and as a result the discussion of that topic suffers. — Jonathan M.

    Recommended Thumb up 0

  • El Biciclero October 28, 2010 at 3:14 pm

    David (& Jonathan)–

    Sorry to participate in the divergence from the topic. I think those of us concerned about the safety of “cycle tracks” feel a twinge of fear when we see this kind of research result–the fear being that such conclusions might be used to promote hasty implementation of less-than-safe facilities. Does slightly cleaner air outweigh the dangers that ill-conceived facilities pose?

    Back on topic, I always worry about the face-full I get every time I have to stop while taking a lane. Reduced exposure to pollution is also cited as a benefit to having “normal” bike lanes because they allow cyclists to stop beside or ahead of exhaust pipes rather than behind them. Some other comparisons that I would find interesting:

    1. Difference in pollution levels while riding (moving) in the lane behind cars vs. while stopped in the lane behind cars.
    2. Difference in pollution levels in a regular bike lane mid-block vs. at the stop line.

    Recommended Thumb up 0

  • BURR October 28, 2010 at 3:42 pm

    I blame cycling in traffic for contributing to my adult onset asthma. It’s just one of the reasons I prefer to travel at lower traffic volume times and refuse to participate in ‘rush hour’ anymore.

    But removing mid-weight diesel trucks with street-level exhaust pipes from city streets (think diesel-powered Ford, Dodge and Chevy pickups, and a variety of box delivery vans)would probably do more for the quality of the air cyclists breath than building cycle tracks will.

    Recommended Thumb up 0

  • El Biciclero October 28, 2010 at 3:49 pm

    Oh–another comparison I would find interesting is how much more or less pollution is actually sucked into the lungs at various exertion levels. The paradox here would be that when taking a lane (moving directly into the exhaust stream) I tend to push harder to try to keep up with traffic. I fear that creates a double-whammy effect for my lungs. I read an article recently that promoted always inhaling through the nose as a healthier breathing technique, one of the reasons being that it filters out more crap than inhaling through the mouth.

    How do cars kill me? Let me count the ways…

    Recommended Thumb up 0

  • jim October 28, 2010 at 4:45 pm

    Are you talking about removing Diesel pickups from all of Portland or just downtown? All of Portland is a pretty big area.
    Have you ever rode down Marine drive near the terminals on a hot summer day? The diesel fumes will make your eyes water.
    I wish there was some sort of a catalytic converter for diesels

    Recommended Thumb up 0

  • jim October 28, 2010 at 4:48 pm

    As we become more european-like we will see more diesel cars.

    Recommended Thumb up 0

  • jim October 28, 2010 at 4:51 pm

    Why not have the path in the center of the road?

    Recommended Thumb up 0

  • Alistair October 28, 2010 at 5:20 pm

    >> are scared away by the back and forth

    It certainly was pretty off-putting that the first comment seemed like a handgrenade in some private war.

    It wasn’t very informative either I think it possible to find an example of a cyclist killed on almost any kind of infrastructure that involves autos. Not saying you don’t have a point BURR just saying that posting a link didn’t make it. Taking time to search further I found there were 13 death in 2008, at that time there were 40 miles of commuter bike lanes with plans to increase to 80 miles of commuter bike lanes over the next two years, in part to get cyclists off the sidewalks and on to the road where they are more visible to cars.

    I found both concerns about the bike line and also note of a city report note that said the city’s report found that bicycle safety in the area (or the accident) had improved. For the three-year period prior to the conversion, city statistics showed an average of more than 12 bicycle-vehicle crashes per year. In the first six months since the conversion, the city reported zero crashes between bicycles and vehicles.


    I sense from the debate two different goals for infrastructure: one is to make bicycling safer for a cyclists not dissimilar to today’s regular bikers.

    The other is to encourage and support new people to bike do not currently use (or particularly love) bikes as transport.

    personally I believe that ultimately safety and efficiency of bicycling improves with the number of bicyclists. I experience better car behavior on well biked routes. It also means more policemen, politicians, planners, pedestrians, voters, journalists and drivers either bike or have sons or daughters that bike.

    So more working on the safety of (rather than avoiding) somewhat segregated facilities which encourage bicyclists onto the road feels like a good path forward. Once we’re at 10-15% mode share for bikes then even more choices are on the table.

    Cheers, Alistair

    Recommended Thumb up 0

  • KJ October 28, 2010 at 6:07 pm

    Interesting BURR # 21
    I used to commute from goose hollow to the industrial eastside and I have sports induced asthma, I needed to use an inhaler. I live in NE now and commute through neghborhoods or through Van/Williams to the esplanade and I no longer need it… my commute is now 3 times as long so…I attributed it to the downtown air quality.

    Recommended Thumb up 0

  • resopmok October 28, 2010 at 6:41 pm

    RIP Share the Road. We are going to have separate facilities shoved down our throats whether we like or not. Perhaps soon laws on the books will ban bikes from roads except where designated just to make sure the cycling public “stays safe and healthy.”

    I bet research will show that less cars on the road also reduces exposure to ultrafine particles, but that won’t happen so we’ll just shuffle all the cyclists off onto their own sidepath. Oh yeah, except we’ll forget to fund the building of it so sorry, out of luck.

    Recommended Thumb up 0

  • Tbird October 29, 2010 at 1:01 am

    Being a proponent of Cycle Tracks in general I’ve gotta weigh in on this.
    The reason that US designed cycle tracks fail to inspire the faithful are as follows:
    1- the refusal of legislative powers to hold motorists legally accountable in ANY and ALL negative interactions between cycle and car (FYI, this is the prime motivational factor to defensive behaviour in the cycle track environment).
    2- (as noted above) The presence of parked cars in the last 10m of a block with right turn creates an unneeded hazard.
    3- The insistence of a certain faction of cyclists that “Sharing the Road” is the only true path to salvation (why would you swim with sharks if you don’t have to?).
    The facts are, in places that have made the appropriate legal, spatial and cultural adjustments Cycle Tracks are a superior means to inspire more, and safer cycle transport. We can’t just install this type of infrastructure and make no other adjustments (which is what has happened in the few instances where they exist. Minn is a prime example). It’s funny that 99.9999% of the detractors have never actually used a well incorporated Cycle Track System. Please know the facts, or at least have used a proper cycle track to make an informed opinion.

    Recommended Thumb up 0

  • Duwayne Anderson October 29, 2010 at 7:26 am

    Great article. Thanks for this research. It might be worth looking at the way Holland builds bike lanes — they keep them (for the most part) well separated from traffic.

    Recommended Thumb up 0

  • Faith October 29, 2010 at 9:02 am

    In the cycle track vs. safety debate, I want to note that the Mpls cycle track noted does not have the design features that make cycle tracks in Berlin or Amsterdam much safer. These include: no parking near intersections (I think around 30′), shifting the cycle track to the area where parallel parking is located at intersections to improve visibility to divers, driver stopping distances further setback, bike traffic signals, lower vehicle speed limits, sharper turn radii, etc.

    These are the design features American cycle tracks lack which in turn reduces their safety. It would be interesting to do a line by line comparison of cycle track facility design.

    Recommended Thumb up 0

  • Dave Thomson October 29, 2010 at 9:28 am

    #29 – Actually if we held motorists accountable and they drove with due caution for vulnerable road users (and each other), the perceived need for cycle tracks would be greatly diminished. A win-win situation.

    Recommended Thumb up 0

  • El Biciclero October 29, 2010 at 9:37 am

    Tbird–I think those that are less enthused (myself included) about cycle tracks have exactly your points in mind. Simply building a restricted area for cyclists without giving any instruction to–or enforcing any violations by–motorists and other road users potentially creates a more dangerous situation than existed without the cycle track. The reason I have never used a well-incorporated Cycle Track System is because I haven’t been able to afford to travel to the Netherlands with my bike to try one out. I don’t believe a single “well-incorporated” cycle track system exists in the U.S.–again, due to the points you make in your post.

    If there is no motivation (other than having to “live with it”) for motorists to look out for and avoid running over cyclists, then the only way to safely operate (without becoming a pedestrian on wheels) is to force oneself into the consciousness of motorists by operating one’s bicycle in an assertive, but cooperative manner that utilizes proven (not experimental) principles of visibility, predictability, destination positioning (not signal-mitigated suicide positioning), etc. I think this is why there is an “insistence” by some that, until such a time as laws, law enforcement, and attitude catch up with newfangled infrastructure designs, sharing the road is the safest and best method we have for traveling by bike.

    I think it would be interesting to implement the suggestions you make in your points 1. and 2. and see how far that gets us with respect to safety and perception of safety. Seems like that would be the least expensive option (although it would probably cost some politicians their careers).

    It’s unfortunate that we have to suck down so much pollution in the process

    Recommended Thumb up 0

  • Tom October 29, 2010 at 12:43 pm

    Since diesels produce a large share of particulates, does the study account for the effects of the 2007 medium/heavy vehicle reduction in allowed diesel particulate emissions over time? Given the economy and that truck operators tend to wait a while for a new engine to be proven, the current share of 2007 compliant engines is probably under 20% and may be even under 10%. But over time this number will increase, probably reaching around half in another five years and 80-90% or more in ten years.

    Diesel cars have also been subject to emission reduction regulations, but I am less familiar with the details, and diesel cars are a lower share of particulates vs medium/heavy vehicles.

    Given this change in allowed emissions, in ten years, how big are the benefits of separated bike lanes, and in ten years would the benefits be greater than some other alternative bicycle investment?

    If there is a further reduction in allowed emissions, or if the improved fuel economy standards result in a further reduction in emissions (improved fuel economy does not always equal reduced emissions and vice-versa) , how big is the benefit vs an alternative?

    Recommended Thumb up 0

  • BURR October 29, 2010 at 3:43 pm

    Minneapolis cyclists hate new cycle tracks:

    Recommended Thumb up 0

  • Alan October 29, 2010 at 4:10 pm

    3- The insistence of a certain faction of cyclists that “Sharing the Road” is the only true path to salvation (why would you swim with sharks if you don’t have to?).

    Mandatory side-path laws mean that, in your analogy, we are only allowed to swim where Big Brother says we can swim, whether or not there are sharks, and that even if we reasonably feel there are sharks in those segregated waters (and there often are) we still must not swim outside of them even if that meant we would be safer.

    That’s ignoring the problem of the analogy that “sharks” are wild creatures with primordial instincts to devour us, not fellow humans as are car drivers, who in rational moments are mostly averse to homicide.

    I don’t know which faction you generalize as such, though. ‘BURR’ and ‘are’, outspoken advocates for public use of public roads in this forum, have made it clear they have no such agenda. They simply don’t want to be legislated off the roads.

    It’s funny that 99.9999% of the detractors have never actually used a well incorporated Cycle Track System.

    It’s funny how many statistics are made up on the spot.

    BTW, I have and in such cultures bikes are also integrated into street traffic, with laws, enforcement and culture protecting them. I’m in favor of that sort of integrated solution as opposed to the ‘force bikes onto segregated facilities’ approach.

    Recommended Thumb up 0

  • Greg October 29, 2010 at 6:45 pm

    “well incorporated Cycle Track System” – where would I find such a beast?

    As for pollution and particulates, I would happily ban all two stroke engines and any vehicle older than 1980 from the road. I can always smell raw gas and exhaust from old cars, esp old Volkswagens. Two strokes are especially problematic since they tend to ride in bike lanes and leave a visible trail of smoke.
    Yeah, you get 80mpg, but you pollute more than 20 new cars.

    Recommended Thumb up 0

  • Jim O'Horo October 30, 2010 at 4:55 pm

    Interesting article Jonathan. Relative pollution exposure on cycle track vs. bike lane is something I hadn’t considered.

    jim @ #8

    There’s no centerline because this cycle track is a one-way facility on a one-way street. I presume the lack of directional arrows is because designers felt the correct direction would be obvious though, given the behavior of some cyclists, that may be overly optimistic.

    Recommended Thumb up 0

  • Jim O'Horo October 30, 2010 at 5:10 pm

    Spiffy @ #2

    I’m with you Spiffy. Pollution decreases as you get farther away from the source! Well, DUH!! That much is a no-brainer once you think about it. Though the study brings up an interesting issue (pollution level vs. distance), I’m a little disappointed because I think the researchers missed an opportunity to more clearly define the distance/pollution relationship with relatively little additional effort. The fact that they found parked cars had little effect shows clearly that this is akin to a diffusion phenomenon. I suspect that measuring at only 2 distances gives a false impression that pollutant concentration falls linearly with distance from source. I think it’s more likely an inverse exponential relationship such as we see with noise or light. It would be interesting to see the results with 3-5 sensors placed at fixed intervals including on the middle of the sidewalk. Such info. would be of more than academic value as it would provide a basis for determining the most cost effective separation distance.

    Recommended Thumb up 0

  • Jim O'Horo October 30, 2010 at 5:15 pm

    BURR @ #21, El Biciclero @ #22 & jim @ #23 & #24

    I think you’re all onto something here. Personally I believe the main source of particulate pollution is diesel exhaust. Gas engines produce much less. El Biciclero, I’ve heard the same things about nose breathing. Also nose breathing prewarms and moisturizes the air entering your lungs. It’s much better if you can do it, but heavy exertion may make that impractical. Incidentally, if you stop trimming your nose hairs, the filtering effect will be enhanced, but you’ll pay a price for social impropriety. [joke!] Besides the problem of processing a greater volume of polluted air during heavy exertion, one is forcing the air deeper into the lungs where particles are more likely to lodge permanently and do even greater damage. If you have a severe respiratory problem, consider taking MAX southbound (uphill) from about Morrison to the end of the line at PSU and cycling in the other direction.

    Jim, I don’t think a catalytic converter for diesels is the solution. Catalytic converters work in the gas phase. Particulates are solid and won’t oxidize in a catalytic converter. In fact they would likely foul and plug the converter.

    “As we become more european-like we will see more diesel cars.” Don’t know about that, but you can bet that if Exxon is successful at developing the Athabaska tar sands in Canada the price of diesel fuel will rise more slowly than gasoline. That will provide economic incentive to buy diesel-powered vehicles.

    Recommended Thumb up 0

  • jim November 4, 2010 at 2:08 pm

    Thanks Jim, I didn’t mean a catalytic converter specifically, just meant some sort of device that would clean the exhaust some

    Recommended Thumb up 0

  • J November 12, 2010 at 5:28 am

    Wow. Coming from New York and Montreal, it’s funny to see such anger from bicyclists directed towards cycle tracks. Perhaps it’s because your streets are much less congested and you don’t have problems with double parking. In New York, the standard bike lanes and sharrows are a cruel joke. Constantly clogged with double parkers, they do little to encourage new cyclists. The new cycle tracks, however, have had a dramatic impact on cycling.

    I also think (and many studies have shown) that bike safety comes with numbers. In Montreal (where I currently live) the cycle tracks would be considered crazy to you guys (2-way on one side of a 2-way street). Yet they get a TON of people out riding, which dramatically increases awareness of cyclists, since drivers see cyclists all the time and become trained to look out for them. Even though the design on it’s own might not seem safe, the effects may actually increase overall safety AND dramatically increase cycling numbers, something sharrows and standard lanes will never do.

    Finally, the issues you bring up about right hooks are valid, but they can be designed for. It is done in Europe for decades and in NYC quite well also. Pointing to the Minneapolis cycle track example is a red herring. It is poorly designed and from what I have read, shunned by many cyclists. Instead, you should look to the state of the art cycle tracks in NYC, which have been extremely popular with cyclists here. Seriously, elected officials and local groups from across the city are clamoring for them.

    Recommended Thumb up 0