Archive for December, 2011

I was checking out the Cedar Rapids Gazette for news about my beloved but apparently cursed Iowa Hawkeyes when I ran across this article about a recent uptick in pedestrian fatalities in Iowa.   While it’s somewhat comforting to know that, despite the vast geographical and cultural differences between them, Oregon and Iowa share many of the same transportation problems, it’s lamentable that there’s not more being done to prevent them.

The most interesting tidbit:

On Dec. 2 a jaywalker was crossing Council Street NE when he was struck by a pickup in the turn lane at 6:40 a.m. Police cited him for failing to use the crosswalk.

Ouch!  Don’t you think the poor fellow perhaps learned his lesson merely from being hit by the car, without the added emphasis of the ticket too?  And no ramifications for the driver at all?  Perfectly legal to keep right on trucking if the pedestrian isn’t in a crosswalk and presently assigned right-of-way by statute or an MUTCD-approved traffic control device?  Really?!  What if it’s a person in a wheelchair?   An elderly person?  A child?

Look, I’m not defending jaywalking here, but I think it’s something we all do from time to time, maybe even without knowing it.  Take a close encounter of the vehicular kind I had last night as I crossed Morrison Street along West Burnside.  I posted a picture of the intersection below.  I might have been guilty of jaywalking here, although I’d argue that there is an “implied crosswalk” along Burnside that I was in when a teenaged driver ON HER CELL PHONE sped around me while leaning on the horn.  Can I cross legally there, rightfully expecting drivers to yield to me as they should at a marked crosswalk?  Or would a good, law abiding pedestrian have walked south on 20th to cross Morrison (where the crosswalk is also unmarked, incidentally) before walking back to Burnside on the far side of Morrison?  I honestly don’t know if I was legally in the right here or not.

Scene of the Crime

Indeed, gazing out my window to gather my thoughts just a second ago, I saw two citizens jaywalk across Harrison Street to catch an approaching streetcar.  This happens often at bus stops as well.  Is this because these jaywalkers are lawless heathens who deserve their fate should they be struck by a car during their transgression?  Or is it because perhaps we fail to serve pedestrians with ample and well-placed crosswalks, and have written the rules of the road to disproportionately favor drivers?

The answer to that question depends upon your belief of the primary purpose of a street.  Mine is that they’re for people, not cars, but if our policies and enforcement are any indication, I’m firmly in the minority there.  C’est la vie.  As a driver, I’m still going to break for pedestrians in the road whether they’re there legally or not, and even if they’re not actually human:

“Often drivers don’t even recognize the figure as a person […] People think they are deer,” Iowa Department of Transportation spokesperson Dena Gray-Fisher said.

Well then.  I must admit, I’ll think more carefully before my next jaywalk knowing there are licensed drivers out there who have a hard time with that whole person-deer distinction.  Well played, Dena Gray-Fisher, well played.

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I have a sort-of philosophical fascination with the chicken-and-egg aspect of right-of-way allocation on roadways.  Should projects reflect the fact that most people still choose to drive as their primary mode of transportation, with facilities for transit, bikes, and the like being added to the mix only as demand for them materializes?  Or should planners try to induce demand for alternatives by allocating capacity for them in advance of demand, hoping to prove the sagacity of that old mantra from Field of Dreams?

I certainly tend to think the latter notion is the smart one, and as the concept of complete streets grows more popular, I think a large majority of people who plan transportation projects for a living probably agree with me.  But politically, such things can be more easily said than done, as controversy over the proposed reallocation of right-of-way on North Williams Street has clearly demonstrated in recent months.

With that in mind, I think the folks responsible for the design of the new-and-improved Sellwood Bridge deserve a big pat on the back.  For cars, the new bridge features the same lane configuration as the old one–one lane in each direction.  But for bikes and pedestrians, the itty-bitty sidewalks on each side are now wide, comfortable paths, clearly demarcated to separate the bikers from the walkers.  In addition to the off-road bike path, there’s also an on-road bike lane in each direction.  The project clearly anticipates (and intends to induce) heavy usage from cyclists, essentially providing them a fast lane and slow lane in each direction.

It gets better.  A few miles downriver, construction continues on the Caruthers Bridge, which will carry nearly every mode of transportation you can think of except for single-occupancy vehicles across the Willamette.  The Caruthers (or whatever it will be called when it’s completed) will serve light rail, bus, streetcar, bikes, and peds.  Combined with the new Sellwood Bridge, that’s a lot of additional capacity for alternative modes to cross the Willamette without adding a single new lane for cars.

This is something that I really can’t see happening in too many other American cities, and I hope these bridges rightfully become points of civic pride as their construction continues.

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My love of applied maths and my good old DC days working for the graphics department of scientific publisher AGU combine to make me quite the data visualization junkie, as many of you have no doubt figured out by now.  So I found this post on the Media Matters website to be a fascinating data point (ahem!) on the public’s perception of what makes an honest graph.

At issue here is a graph of unemployment figures from 2011 shown yesterday on Fox News.  Notice that the data point for November is plotted incorrectly, giving the appearance of no improvement when in fact there was some.

Media Matters is right, obviously, in pointing out this discrepancy, although I thought that the additional graphic they included just to illustrate this simple point (not pictured here) was a tad unnecessary.  What I found really interesting is the alternative they offered, which was put forth as an “honest chart:”

In the strictest sense, all of the data points are plotted where they should be, so everything appears on the up-and-up.  But is that sufficient to make a graph honest?

Edward Tufte, a pioneer in the field of data visualizing and information design, states the following oft-referenced principle in his book The Visual Display of Quantitative Information:

The representation of numbers, as physically measured on the surface of the graphic itself, should be directly proportional to the quantities represented.

Tufte introduces a quantity to measure a graph’s performance versus this standard which he calls “lie factor,” defined as the effect shown on a graph divided by the effect shown in the data.

So how does Media Matters’ “honest” graph measure up?  I’d argue that the right portion of the chart appears to show that the unemployment rate plummets between October and November, declining by about two thirds of the height of the chart.  But in reality, the decrease is only (9.0%-8.6%)/9.0% = 4.4%.  So the lie factor here would be 66%/4.4%.  That means that this graph, with a lie factor of 15, overstates the effect of the data by a whopping 15 times!

This is likely an honest mistake, as Excel, R, and other commonly used plotting programs often default to using a y-axis range just larger than the data range, leading to the graph held up as the standard by media matters.  But even an honest mistake can lead to a dishonest graph.  Just for fun, I extended the y-axis to 0 so as to eliminate any lie factor; here’s the resulting graph:

The beginning of what appears to be a downtrend is visible in the latter half of the year here, with a decent but not earth-shattering drop between October and November, and numbers otherwise appearing rather high.  This is probably a pretty accurate representation of unemployment numbers, but that’s just a lucky break for the most part.  What if I were plotting, say, today’s hourly Dow Jones index values?  This has fluctuated between 11,990 and 12,100 so far today, often wildly.  But extending my y-axis to 0 would certainly mean my chart would fail to show these effects at all.  Limiting it would introduce some degree of misrepresentation.  So how should I set my y-axis values to show trends and fluctuations while at the same time not exaggerating any effects?

I think this is a difficult question, and one whose answer depends heavily on the situation.  For the unemployment numbers, I think adding some context to the numbers is helpful, so I plotted lines representing the historic (1948-2010) average unemployment rate as well as all-time high and low values.  Despite the fact that I introduced a (small in this case) lie factor by moving my y-intercept up to 2% in the new graph, I think this paints a pretty accurate picture.

Data visualization is a subtle art, and one that I fear too few people responsible for writing scientific publications, news articles, and the like fail to fully appreciate.  As consumers of this information, I’d encourage everyone to look at these with a skeptical eye and check twice to be sure that they’re accurately representing the data.

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