Tag: roadways

Carnage culture: Extrapolating blood alcohol content levels

June 20, 2011 / / 0 Comments

A breathalyzer test, to measure an automobile driver’s Blood Alcohol Content (BAC), is not always administered at the time and scene of a crash. I don’t know why it took four hours for Drew Forquer to have his BAC measured, but it registered at 0.045 percent, slightly more than half the legal limit of 0.08 percent.

Drew was convicted on Friday, June 17, 2011, of reckless homicide and aggravated drunken driving, but not “aggravated DUI charges that specified he was over the legal limit.”

…but the judge said it was clear to him simply from the results of field-sobriety tests, eyewitness testimony and Forquer’s “bizarre” turn — which was caught on surveillance video — that he was impaired.

The prosecution hired an expert witness to extrapolate Drew’s BAC at the time of the crash, “estimated…to be from 0.084 to 0.123 percent.”

What extrapolation means

Using evidence, prosecution and defense argue about the estimated BAC based on a variety of factors, including:

  • witness statements about driving behaviors (prosecution)
  • evidence of drinking before or during crash (prosecution)
  • field sobriety test (prosecution)
  • individual’s metabolism (defense)
  • “what the driver ate or drank that day” (defense)
  • other health issues (defense)

(The parentheses indicate which side used the factor in Drew Forquer’s case.)

In Drew’s case, his defense attorney argued that the BAC was lower because him having liver disease and chronic alcoholism would have slowed his metabolism (meaning alcohol would enter the blood stream more slowly).

Drew awaits sentencing, which can be from probation to 15 years in prison. They must be joking about probation – he’s gone to court for four previous DUI arrests!

More carnage culture articles

Story sources

Chicago Tribune – Thursday, June 16, 2011

Chicago Tribune – Friday, June 17, 2011

A taxi driver exited Lake Shore Drive and drove across the grass separating it from the Lakefront Trail. This photo, taken on July 4, 2010, is not related to the story above. Photo by Andrew Ciscel.

The 3-way street

June 9, 2011 / / 0 Comments

Update June 12, 2011: Added a link to and excerpt from commentary by David Hembrow, a British blogger in the Netherlands.

How does a 3-way street work? Easy, just watch the video.

I like the term “aggressive yield” to describe the situation when a motorist does yield to pedestrians crossing the street, but in a way where they inch forward continually, slowly pushing, with a buffer or air, the people out of the way.

I really like the comment from Tuesday by Anthony Ball:

those red markers are just showing the limits of tolerable risk as established by years of system development. If the collision speeds were higher, those red circles would be far few – it’s simply a system finding its own point of stability.

If you really want to wreak havoc – try to control that system without corrective feedback (eg more rules, lights, controls, etc) and you’ll see the system kill people while it tries to find new stable relationships.

don’t forget that rules, signs, lights, etc have no direct impact on the system – they only work through the interpretation of the users.

What did David Hembrow have to say? David lives in the Netherlands and disagrees with the common sentiment that these conflicts are caused by selfish users.

I don’t see the behaviour at this junction as being about “bad habits”. What I see is simply a very badly designed junction which almost invites people to behave in the way that they do.

Dutch road junctions don’t look like and work like this – they are different for a reason: it removes the conflicts and improves safety. A long-standing theme of Dutch road design is the concept of Sustainable Safety. The concept is to remove conflict so that collisions are rare and the consequences of those which remain are relatively small. Roads are made self-explanatory so that bad behaviour is reduced and the way people behave is changed.

Reading this reminds me of the work of the students in George Aye’s class at SAIC, “Living in a Smart City.” The students attempted, through an intersection redesign, to reduce the stresses that lead to crashes.

Where are the 3-way streets in your city? Grand/Halsted/Milwaukee in Chicago comes to my mind easily. Also a lot of streets in the Loop. Oh yeah, and The Crotch, at Milwaukee/North/Damen.