Prufrock

Let us go then, you and I,
To a deluxe apartment in the sky.

-T.S. Eliot meets The Jeffersons

SD-FO ought to STFU

The next person who mentions the terms "structurally deficient" or "functionally obsolete" in my hearing will be punched in the mouth.

From talking heads on cable news to engineers and policymakers who really ought to know better, misuse of these terms has been rampant since at least August 2007. Let's set things straight with a healthy dose of facts and the not-so-subtle threat of violence.

Structurally deficient (SD) means that load-carrying elements of the bridge have been rated as "poor" or worse (4 or below on the National Bridge Inspection Standards scale of 0-9, where nine is brand-new and zero means the bridge has fallen into the river) or that the waterway opening provided by the bridge is inadequate¹.

Functionally obsolete (FO) means the bridge is inadequate from the perspective of roadway geometry issues¹ (traffic capacity, roadway shoulder width, and approach sight lines, for example).

Let's examine the abuse of these terms in detail:

First, and most importantly, SD and FO are planning, not structural engineering, terms. They do not necessarily reflect the safety or serviceability of a bridge. Bridges designated as SD or FO get higher priority for repair and rehabilitation. As a consequence of this, it can actually be good for a county engineer to have a bridge designated SD or FO - state or federal money may then become available.

Structurally deficient is not a synonym for "unsafe" or "near collapse." Recall that the SD designation is based upon a load-carrying element being rated 4 or below on the National Bridge Inspection Standards (NBIS) scale. 4 is basically the lowest rating at which an element can be left in place as-is. You have probably driven over a bridge with an element rated 4 within the last seven days. That doesn't mean your life was in danger.

Reporting the sum of SD and FO bridges is especially meaningless from a bridge safety perspective. I can't tell you how many presentations I've attended where the first words from the speaker's mouth were "Since X percent of the nation's bridges are structurally deficient or functionally obsolete..." - from a safety perspective, this is about as meaningful as saying "X percent of the nation's bridges are painted green." FO has absolutely no structural safety meaning. A bridge can be rated FO because its shoulders are too narrow, or because it has an old-style guardrail. That doesn't mean the bridge is going to fall down. One very common cause of an FO designation is that traffic has increased on the route carried by the bridge. A bridge can be deemed FO even if it has a good structural rating of 7, 8, or 9. So, while FO bridges ought to be upgraded or replaced to maintain good levels of service throughout the network, an FO designation doesn't provide any more indication of a bridge's safety or serviceability than the color of the bridge paint. If you're trying to make a point about structural capacity, don't inflate your numbers by counting FO bridges too.

The federal definition of a "bridge" is any structure with a clear span of at least 20 feet². That includes everything from the Golden Gate Bridge down to structures that are little more than oversized culverts. The SD and FO criteria may be applied to any structure in this spectrum. When we refer to the number of SD/FO bridges, an outdated bridge on a low-volume county road counts the same as the heavily traveled (and both SD and FO) Milton-Madison (Kentucky/Indiana) Bridge, a regionally important Ohio River crossing which, if out of service, necessitates a detour of 55 miles. Of the 600,000 or so bridges in the United States, the vast majority are "boring" bridges with relatively short spans and lots of built-in redundancy. That means that even if a structural member is deteriorated, there is still enough load capacity too keep the bridge in service.

Bridge collapses are shocking in part because they're so rare. Regular inspections in keeping with the National Bridge Inspection Standards help keep them that way. Yes, we should be sure that bridge maintenance and inspection is adequately funded; yes, research into improved methods for structure evaluation and testing should continue - but there's no reason to panic over big numbers with scary-sounding sames that ultimately have little meaning from a safety perspective.

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^1. Federal Highway Administration: Bridge System Conditions - Explanation of Bridge Deficiencies

^2. United States Code: 23 CFR 650.305 (2009).

Flags: District of Columbia

I am pleased to write about a flag that is doubly special: (1) it is the flag not of a state of the Union, but the Federal District, and (2) I am currently in this District. I love when my travel schedule aligns with my geographic nerdosity.

The authorization for a special federal district, not to be a part of any state, as the seat of national government was laid out in Article I, Section 8 of the Constitution, which grants the Congress authority

To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten Miles square) as may, by Cession of particular States, and the acceptance of Congress, become the Seat of the Government of the United States, and to exercise like Authority over all Places purchased by the Consent of the Legislature of the State in which the Same shall be, for the Erection of Forts, Magazines, Arsenals, dock-Yards, and other needful Buildings;

Conveniently, the Constitution now spends most of its time in "such District." Now, I once thought that the creation of the Federal District was mandated by the Constitution, but the excerpt above suggests that Congress was allowed, but not required, to establish a seat of federal government distinct from any state. Anyway, the Federal District was established along the Potomac River, on land ceded from Maryland and Virginia - though Virginia got its cession back in 1846. Until then, the District of Columbia had been divided into two counties: the county of Washington on the north bank, and the county of Arlington on the south. Similarly, there were multiple municipalities in the District: until 1871, letters could be properly addressed to Georgetown, DC. The Organic Act of 1871 unified the City of Georgetown, the City of Washington, and the County of Washington into a single legal entity, the District of Columbia.

So, while DC as we know it came into existence in 1871, it wasn't until 1938 that it adopted its spiffy red-and-white flag. The banner is based on the three stars and stripes from the shield on George Washington's family coat of arms. I heartily approve - it is instantly recognizable, and simple enough for schoolchildren to draw. The citizens of the Federal City seem to dig it - it appears on non-governmental logos and is flown from non-governmental buildings throughout the District.

The official motto of the District - Justitia omnibus ("Justice for all") - and the license plate slogan, "Taxation Without Representation," are not-so-subtle digs at the governance of the Federal City. Citizens of DC have a non-voting delegate in the House of Representatives, and only won the right to vote in presidential elections in 1961, with the ratification of the 23rd Amendment to the Constitution (they didn't actually get to vote until the presidential election in 1964).

As far as I can tell, the selection of the wood thrush (Hylocichla mustelina) as the official bird, or the scarlet oak as the official tree, of the District carries no specific political message. Too bad.

Be brave, like prawn

Menu boy no be coward, like shrimp; menu boy be brave, like prawn.
-The Simpsons, Episode CABF01, "Lisa the Tree Hugger"

I took a picture of this giant freshwater prawn (Macrobrachium rosenbergii) at the Smithsonian National Zoo in Washington, DC, specifically so I could make a motivational poster for Lisa. Having completed my mission, I'm now filled with rage - it turns out that Macrobrachium and many other so-called "prawns" are not true prawns at all: they are freshwater shrimp. Some helpful Australians have provided clarification:

...there is one sure way to tell them apart. In shrimps or carideans the side plate of the second segment of the abdomen overlaps the segments in front and behind. Prawns, most of which belong to the family Penaeidae of the group Dendrobranchiata, have all the abdominal side plates overlapping tile-like from the front. A more fundamental difference but one impossible to appreciate in a single specimen is that female prawns do not brood eggs but shed them into the currents where they develop independently. It would therefore make sense to call all member s of the Penaeidae "prawns" and members of the Caridean "shrimps" and this is what most Australians do....Confusion arises when we hear Americans refer to prawns as "shrimp".

So that settles questions of anatomy, but not courage. Is there any relationship between location of abdominal segmants and strength of character? I leave that to the decapod philosophers.

Katy didn't

Lisa spotted this character at the front door to our building. It's a katydid. My best guess based on a minimal amount of half-assed research is that it belongs to the genus Microcentrum. When I saw it, I told Lisa it was a leafhopper. This was based on two critical observations:

1. It looked like a leaf
2. It looked like some kind of grasshopper

QED, right? Wrong. It turns out that a leafhopper is a completely different type of insect which hops on leaves, rather than resembles a leaf. Leafhopper are also really tiny. There goes my entomology career.


I can conclusively say, though, that...it is green.

Three-chambered peanuts!

MARSHFIELD, WISCONSIN - My friend Aaron and I were sitting on his back porch eating peanuts and drinking beer. when something totally unexpected happened: one of us found a three-chambered peanut...and then it happened six more times. I know, right? Seven three-chambered peanuts in one bag - what a time to be alive.

Angry eagle law firm

Do some aspiring attorneys dream of practicing angry eagle law, or does it just happen?

It happened in Tucson, Arizona, on Valencia Road, just west of the airport. Whether you need to sue over unlawful regurgitation or defend yourself against charges of kleptoparasitism, the Angry Eagle Law Firm has you covered. You can celebrate your assured victory across the parking lot, at the Happy Chicken restaurant.




Angry Eagle and Happy Chicken, staring each other down across the Arizona asphalt - I wonder if anyone at the zoning board chuckled when these building permits were issued.

Coordinates:
32.13412 N, 110.97922 W (WGS84)

You can see the avian showdown in Street View.