I run across numerous acronyms and initialisms in my job. It’s not as bad as the military, but there are plenty, let me tell you.
I’m reading a report this morning and happen across the following quote, which lists an interesting initialism:
The High Hazard Location System (HSP) is a flexible…*
HSP? Where did they get that? Freaky…
*NCHRP Synthesis 295: Statistical Methods in Higway Analysis
This link takes you to the google-hosted video of an exercise conducted by some students. They examined the effect on I-285 around Atlanta when everyone is forced to drive the legal speed limit (55 MPH).
Some background for anyone who doesn’t live or drive around Atlanta: I-285 encompasses the entirety of the downtown metropolitan area, plus all of the inner subburbs. It’s about sixty miles in circumference, and all of it is signed at 55 MPH (I think—not too familiar with the east side), by ordinance, I assume. 55 MPH on I-285 is rather slow in freeflow conditions. Generally the median speed is around 60 MPH and the 85th percentile speed is probably around 65 MPH (let me emphasize that these are personal estimates. I have not done any speed studies). So, 55 MPH is going to be, outside of congested conditions, around the 20th or 25th percentile; 80% of people will want to travel faster if given their druthers.
What does this all boil down to? Watch the video and see. It’s impressive.
Of course, if you do a Google search on this thing and read some of the comments, you will find a large number of people who think that this was just a stupid stupid dangerous prank that proved nothing. Others think that this shows the uselessness of a speed limit that is set too low and not enforced.
My opinion goes with the latter people. It is silly to have a speed limit which is artifically low and not enforced. Several studies (here, and here, there are others) demonstrate no increase in crashes or crash severity by increasing the speed limit to the 85th percentile speed. These same studies show that reducing the speed limit has no actual effect on drivers’ preferred travel speeds. Agressive enforcement will cause drivers to adhere to a low speed limit, but the effect has no lasting duration. As soon as the enforcement is gone, drivers will return to their previous practice.
Anyhow. The video is cool. Have a look.
Argh!
I, admittedly, am not a fizzisist. However, as a Mechanical Engineering graduate specializing in mechanical design, I was more in tune with it than (say) your average Civil Engineering graduate specializing in transportation. For example:
From the AASHTO, “A policy on Geometric Design of Highways and Streets (2004),” pg. 135, here is the following paragraph:*
An electronic accelerometer provides an alternative to the ball-bank indicator for use in determining advisory speeds for horizontal curves and ramps. An acclerometer is a gravity-sensitive electronic device that can measure the lateral forces and accelerations that drivers experience while traversing a highway curve (65).
In defense of the writers of this policy, I must admit that I am not the specific target audience. This policy has been written so that everyone from technician level and up can read and understand the basic ideas behind road design. However, that does not excuse sloppy physics, in my opinion.
The second sentence of that paragraph repeats the first sentence, in essence, and makes two bad statements and one falsehood. Yes, an accelerometer could sense “gravity”, but not while you’re immersed in the gravity-in-question’s reference frame. I challenge anyone to go out and buy an accelerometer and measure the earth’s gravity; Yes, an accelerometer measures acceleration, we got that; NO, an accelerometer does not measure lateral forces!
I could go deeper into the uselessness of the paragraph, regarding the industry-wide use of ball-bank indicators, and how no one really cares about the actual accleration, except as it applies to a conversion to a ball-bank reading, and how a ball-bank indicator is an acclerometer, but I won’t.
I hate to sound peevish and petty, but that paragraph really bugs me. It’s one of those “flesh it out” paragraphs that are unnecessary but placed in a report (or policy) merely to add weight. [sigh]
Again, in defense of the policy writers in question, when sticking to road design, this is an excellent manual. But the physics needs some work.
* Note Added 10:20 AM: I always have to go to the wife for my proper APA or MLA or Chicago references, so don’t kill me for the improper citation.
* Note Added 10:39 AM: Damn Typos! I’ve fixed four since publishing this.
I guess I’m feeling strangely verbose today. Already this morning, I’ve posted two non-trivial comments over at Live Journal, which are locked to friends only (so sad); I’ve responded to several workish emails in greater-than-two-word-sentences; I cruelly insisted on discussing (at least attempting to discuss) day plans with my wife while she was sleepily lying face down on her pillow making little tiny noises which—roughly translated—meant “fuck off”; and now I’m placing an unusual amount of text on my own blog.
How odd.
Apparently a garbage truck struck and knocked down a large overhead guidesign on Interstate 805 in San Diego. Here’s a forbes article, but it’s not very detailed. I’m trying to find a picture, but no luck so far. At least one person was injured when the sign struck a car.
Two-minute-later update!
Without trying to minimize the depth of tragedy concerning the death of a six-year-old boy when a Southwest jet slid off the runway in Chicago, (stories here, here, and here), the traffic engineer in me wonders how an investigator would code that crash?
There are the obvious codes for collisions with vehicles, deer, lamp posts, guardrail, ditches, mailboxes, etc., but with a quick check of the Georgia Department of Transportation’s coding scheme (which is in the only one I have immediately available), the only categories that might apply are “Other Object (Not Fixed)” or “Motor Vehicle in Motion – In Other Roadway.” The next obstacle would be that the vehicle at fault is the one that is used to categorize the collision, which in this case would be the aircraft striking another “Motor Vehicle in Motion – In Other Roadway.” Again, trying to convert the police report to the collision database will be a fun task for whomever gets it, I’m sure. Without specifically requesting the crash report, someone (like me) who happens to look at the collision data for that roadway would have no idea that a 100 ton aircraft caused this wreck.
Arguably, and I’m willing to be the arguer, this collision should be entirely disregarded when analyzing the traffic safety of this road section. Yes, it’s a fatality, but the circumstances are not ones which are within the bounds of the traffic engineer to solve (I’m sure the airport and airlines would object to a 20′ wall across the end of their runway). However, it would be difficult to disregard this fatality if you were merely analyzing the crash data because you would have no idea (without special knowledge) that an aircraft was involved. Fatalities get an awful lot of attention when collision analyses are conducted so this one wreck could disproportionately affect the amount and kinds of money spent on this roadway.
My Two Cents. This isn’t something earth-shaking in the traffic community, it is merely interesting. And tragic, from the point of view of the family of the deceased.
Post script: In my experience, in cases similar to this one where weather is a factor, some police officers would tend to cite the driver of the out-of-control vehicle for failure to drive safely according to conditions. I wonder if the airline pilot received one? That is done by the officer on the scene to firmly establish which driver was at fault. This incident messes with some of the nice boundaries that traffic and safety engineers are usually safely ensconsed behind.
The is the title of a document being worked on for the Federal Highway Administration.
“INTEGRATED PLANNING WORK GROUP BASELINE REPORT AND PRELIMINARY GAP ANALYSIS: DELIBERATIVE DRAFT”
Without investigating it, I have no idea what this means, and this is supposed to be my career area (generally).
If you want to know, you can go to
http://www.trb.org/news/blurb_detail.asp?id=5292
I heard a fascinating story this morning on National Public Radio’s Morning Edition concerning the (polite) dispute between Denmark and Canada over a tiny rock island in the Nares Strait between Greenland and Canada proper.
The NPR story mentioned that with the retreat of polar ice, the Northwest Passage may start becoming navigable year-round. This would attract shipping looking to cut the distance between Europe and Asia by a significant amount. This article mentions that oil supertankers would find this route particularly beguiling because they are unable to transit the Panama Canal, forcing them into a passage around the tip of South America.
Canada claims the Northwest Passage as territorial waters, and the U.S., for one, claims it is an international strait, subject to the regulations thereof.
I realized while listening that I had no earthly clue what the laws regarding international straits are. Thus, my blog.
As posted in the NY Times, a company in Arlington, VA (the same responsible for sending two tourists thus far into orbit) has announced a $100 million price tag for a trip around the moon.
Their website, spaceadventures.com, did not have any immediately available information as of this posting. Keep your eyes peeled.
This past Saturday was an interesting day for me. In celebration of my 20th birthday (I’m 1F until Tuesday), I decided to give myself the gift of leaping from an airplane. This was something that I had always wanted to do, at least once, before I croaked. Therefore, I made an appointment to take the Accelerated Free Fall course from the Atlanta Skydiving Center in Cedartown, GA.
Google Maps link showing the airport and the Atlanta Skydiving Center. You can see the small orange cross which marks the target area.
I and two other gentleman participated in the first step of the AFF program, conveniently known as AFF1. This involved basic knowledge of skydiving, the rig, proper positioning, procedures, and emergency procedures. All in all, the classroom aspect of the course took about 4 hours, and then we were ready to make our first jump.
I received my flight load assignment (#10) and my instructor (Katie) took me through the procedures one last time for exiting the aircraft and going through the skydive (She’s very admanant on remembering to take deep breaths). Then we walked up and climbed aboard the aircraft that would deliver me to my Date With Destiny.
Without checking my logbook I can’t say for certain which aircraft we went to altitude in, but I’m sure that it had onboard stomach-butterfly-generation equipment. Said butterflies were merrily churning away as the plane zoomed up to altitude.
Aside: I’ve never been in an aircraft before that wasn’t a commercial jetliner or a Cessna. This one beat the pants off them all for willingness to get UP in the sky, NOW!! Quite a ride it was.
As we approached the jump altitude of 14,000 ft, my jumpmaster and mistress (JM), Danny and Katie, made sure I was checked out with what I was going to be doing exiting the aircraft. I’m sure part of the reason they do this is to make sure you are still breathing and that you remember what you spent all that time on the ground learning. Danny had fun making ribald jokes at my, and everyone elses, expense. Lesson’s learned: Don’t wear your goggles until you’re almost ready to go; they fog up.
At 10,500 ft. AGL , a team of four skydivers went tumbling out the door and the plane churned the rest of the way to 14,000. Two more people, one skydiver, one video person, made their jump, then it was my turn.
I must say, once I was up and moving, I was fine. Of course, it was quite a rush to get my feet positioned against the edge of the door and stick my entire body into the airstream coming off the prow of the aircraft (the door was to port, by the way), with the hull sandwiched between my hands. I faced forward in the correct arched position, checked in with my main JM, checked out with my reserve JM, then I stepped out into the wild blue yonder (correctly arched of course).
The rush of falling from the plane was awesome! I took a few seconds to make sure I was correctly positioned, performed the HARM check (heading, altitude, reserve JM, main JM) and did my three practice touches on my pilot chute handle. Well, I should say that I *tried* do do the three practice touches. It’s a lot more difficult to find the handle with 105 knots of airspeed rushing past you, pushing your hand around. My main JM (Danny) helped me find the handle for those three touches.
After that, it was relax, breathe, extend my legs a bit, and enjoy the ride. I found myself keeping a close eye on the altimeter; I suppose I was being paranoid, but I didn’t feel like screwing up the skydive by forgetting to do my pull at 6,000 ft. At 6,000 ft, I did my wave-off, and pulled the pilot chute (without assistance from Danny) and waited for what seemed a long time before THWUMP! my canopy deployed.
(I realized once I was halfway down under canopy that I’d forgotten to count to three and then look over my shoulder to make sure the canopy was deploying correctly. Whoops.)
The first thing I said to myself after pulling the chute was, “oof,” as the canopy inflated, then, “Holy crap,” as I realized I’d just fallen 9,000 feet. Wow. I reached up, pulled the steering loops out of their holders, and played around with flying the canopy. I wasn’t quite as daredevilsh as I could have been; I never went swooping directly at the ground. Instead, I concentrated on turning left, turning right, practicing a flare, and generally setting myself up to land.
Once I was nearing 1,500 ft. (keep an eye on your altimeter!), Danny started talking me in over the radio. Solid comments like, “You’re too high, burn off some altitude,” to “left-left-left-left-LEFT-LEFT-LEFT!” With him coaching, I steered through my downwind leg, my base leg, and he got me onto a perfect approach path. As I slipped down to the landing area, I jumped the gun a bit, not waiting for Danny’s command to flare, and ended up doing a swoop-drop-swoop-thud, “oof” into a stand-up landing. I was momentarily psyched by my good landing, then the chute tried to drag me off of my feet. I got it down and gathered up and walked back into the hangar. My jump was all done.
Thoughts on the jump:
1) The reason I did this the way I did (AFF vs. having a Tandem) was because I figured that if I were to make only one jump in my life, I wanted to pull my own chute and I wanted to fly my canopy in. However, if I knew then now what I know now, I would have gone with the Tandem. I could have concentrated much more on the feelings of freefall, without worrying about the procedures that I needed to undertake. Sitting here, I cannot consciously remember the exact feeling of leaving the aircraft. I remember stepping away, then I remember being in the freefall arch, but it’s a bit fuzzy between those two moments. Maybe I closed my eyes? So, I should have done a Tandem.
2) It was freaking spectacular! I think I’ve decided to keep going and do it again, which means I’ll be doing at least 6 more jumps to get my USPA “A” certification, which would enable me to show up at a drop zone, hitch a ride to altitude, and jump solo.
3) The Atlanta Skydiving Center puts together a cool video for sale. I anticipate that I’ll have one done on my first solo dive. I recommend them.
Jenn commented last night that she doesn’t know anyone who only jumped once. Well, I’d hate to disappoint her.