Wed, 02 May 2018
Addenda to recent articles 201804
Andrew Rodland and Adam Vartanian explained ramp metering. Here's M. Rodland's explanation:
ramp metering is the practice of installing signals on freeway onramps that only allow one car every few seconds, so that cars enter the freeway at evenly-spaced intervals instead of in bunches and don't cause as many problems merging.
He added that it was widely used in California. McCain is headquartered in California, and mentions frequently on their web site that their equipment conforms to Caltrans standards.
M. Vartanian and Richard Soderberg also suggested an explanation for why the traffic control system might also control sprinklers and pumps. M. Soderberg says:
DOTs in California and presumably elsewhere often have a need for erosion control on the steep inclines of earth surrounding their highway ramps. So any time you see a 45-degree incline covered in greenery, chances are it has a sprinkler system attached and carefully maintained by the DOT. Those same sprinklers are often within a few feet of the ramp's metering lights…
That makes perfect sense! I had been imagining fire sprinklers, and then I was puzzled: why would you need fire sprinklers at an intersection?
Several readers suggested explanations for why soldier fly larvae are more expensive than pork chops. I rejected several explanations:
Hogs are kept in poor and inhumane conditions (often true, but their accommodations must still be much more expensive than the flies’)
Hog farmers are exempted from paying for the negative externalities of their occupation such as environmental degradation and antibiotic resistance (often true, but the fly farmers cannot be paying that much to offset externalities)
Slaughterhouse waste and rotten fruit are more expensive than the corn and soy on which hogs are fed (I think slaughterhouse waste and waste fruit are available essentially free to anyone who wants to haul them away)
The drying process is difficult and expensive (but the listed price for undried maggots is twice as high)
But I find Marcel Fourné's suggestion much more plausible: the pork price is artificially depressed by enormous government subsidies.
I started looking into the numbers on this, and got completely sidetracked on something only peripherally related:
According to the USDA Census of Agriculture for 2012, in 2012 U.S. farms reported an inventory of 66 million pigs and hogs, and sales of 193 million pigs and hogs. (Table 20, page 22.)
When I first saw this, I thought I must be misunderstanding the numbers. I said to myself:
!!\frac{193}{66}\approx 3!!, so the inventory must be turning over three times a year. But that means that the average hog goes to market when it is four months old. That can't be right.
Of course it isn't right, it isn't even close, it's complete nonsense. I wrote up my mistake but did not publish it, and while I was doing that I forgot to finish working on the subsidy numbers.
James Kushner directed my attention to the MUTCD news feed and in particular this amusing item:
the FHWA issued Official Interpretation 4(09)-64 to clarify that the flash rate for traffic control signals and beacons is a single repetitive flash rate of approximately once per second, and that a combination of faster and slower flash rates that result in 50 to 60 flashes per minute is not compliant…
James writes:
I imagined a beacon that flashed once every ten seconds; after five such iterations, there was one iteration where the beacon would flash fifty times in a second. "But it flashes 55 times every minute, so, you know, it, uh, conforms to the standard..."
But the Official Interpretation also says
You asked whether the FHWA would be willing to consider experimentation with alternative flash rates for warning beacons. Any requests for experimentation would be evaluated on their merits and would be addressed separately from this official ruling.
so there is still hope for James’ scheme.
Two readers suggested musical jokes. Jordan Fultz asks:
Q: How does Lady Gaga like her steak?
A: Raw, raw, raw-raw-raw!(This is Bad Romance)
And betaveros asks:
Q. What kind of overalls does Mario wear?
A. Denim denim denim.(This is the Super Mario Bros. Underworld Theme)
I feel like we might be hitting the bottom of the barrel.
Thanks to all readers who wrote to me, and also to all readers who did not write to me.
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