CFIs & XDLs

I stayed home from work yesterday because I needed to study for the FE or the EIT (Fundamentals of Engineering exam or Engineer In Training exam). I probably haven't mentioned it in a while, but for your benefit (or your boredom) I can be redundant: I am a civil engineer who has yet to take the first real step toward becoming a professional. I used a lot of the time during which I was awake yesterday by reading my transportation engineering book and doing example problems. I am quite happy about the understanding that came to me regarding particular topics that I had not managed to understand as a result of my study of them for the first time or the second time or the third time. I started off with vehicle performance and moved onto vertical curves and sort of skipped over horizontal curves and read about pavement design, levels of service, cues, etc.

Today, while my boss was looking at some of my work (because he is a professional engineer with a stamp and I am not so that I have not), I opened a civil engineering magazine and read an article about reducing congestion at intersections (yes, the kind related to transportation engineering). This article had been written all about a particular engineering solution called a continuous flow intersection. When I first saw the phrase, I thought that the article must have been written about roundabouts (you know, those approximately horizontal rings of pavement onto which and off of which vehicles turn right, but never left). I was wrong.

The CFI (which has also been called a crossover displaced left-turn intersection) is something that I wish that I had invented, and I should have thought of it sometime, but I was always too lazy to concentrate on solving such a problem because I assumed that if such a solution existed, the Washington State Department of Transportation would have thought of it long ago. It turns out that I would not have been the first to imagine such a solution since the CFI was conceived a good twenty years ago, but coming up with a similar idea independently would have been nice.

I suppose that I should let you know what the idea is: http://www.abmb.com/cfi.html

I have read that this solution has only been built at about fifty intersections in the world and that most of those are in Mexico. Take a look at the animations at the above URL and tell me if you don't think that a couple of the traffic lights shouldn't be replaced with yield signs. Perhaps someone should invent a conditional yield signal.