Friday, March 12, 2010

The Ramp Meter And The Counter-Intuitive

Some things surprise you. Sometimes, after you’ve thought about them, or somebody tells you how they work, they make sense. I’m not competent to do more than mention sub-atomic physics.

Once I was tutoring the adopted daughter of some friends. This kid was in the ninth grade, and had endured the kind of traumas you wish were media fantasies. She was bright, but had tentative diagnoses of all the mental disabilities about which you might’ve heard. Man, she could frustrate me. Areas. Volumes. Fractions. It was fascinating how much she couldn’t get, but I taught her to play chess, and she could clean my clock. That’s got nothing to do with things that are counter-intuitive, but once, probing a little bit, I asked her what weighed more, all the whales in the ocean or all the plankton.

I really didn’t learn anything. She answered wrong, but so would most of us. The answer is plankton. Why are there more foxes than mice?

Here’s one. Decades ago, a researcher at the University of Washington removed the (predator) starfish, Pisaster ochraceus, from an intertidal pool that contained fifteen species of marine invertebrates. You’d think that you’d get more of the starfish’s prey, or at least that the prey populations would rise until there was a crash. What happened was that the number of species dropped to eight. In fact, a kind of sponge, and its predator, neither of which had an obvious relationship with ochraceus, disappeared. The hypothesis is that the starfish cleaned the habitat for the sponge.

Here’s another. A. C. Crombie, of the University of Cambridge kept two species of beetles -- Tribolium and Oryzaephilus -- in flour. Usually I try to keep bugs out of my grain, but -- you know -- British academics have a reputation for eccentricity. Usually Oryzaephilus disappeared, and the Tribolium population would level off at about 125 beetles per ten grams of flour. Then old A. C. stuck some glass rods into the flour. (A. C., you maniac!) Oryzaephilus got up into the eighties or nineties per ten grams, and Tribolium -- wotta champ! -- leveled off around 225.

Here in Minneapolis, we have these things called ramp meters. Between us, St. Paul, and the suburbs, we have 433. They’re like stoplights, only there’s no yellow, just red and green. During rush hours, they act like valves, letting cars onto the freeway at measured intervals to keep us from bunching up. Actually, the one I use lets the cars through quickly enough that we end up queuing again right at the freeway. I can’t see how this helps, but I’m not a traffic engineer.

Anyway, ten or a dozen years ago, a state legislator from out in the country somewhere, didn't budget enough windshield time once too often, and made ramp meters his personal hobby horse. There was a bombastic morning-drive disc jockey who whined about them, too. In 2000, Minnesota paid a firm called Cambridge Systematics $650, 000 to turn the ramps off for eight weeks and write a report. During the eight weeks, freeway volume went down nine percent, travel time went up 29%, speeds dropped 7%, and the number of crashes went up 26%. So a politician’s and a disc jockey’s ignorant peevishness cost Minnesotans six hundred and fifty grand, plus whatever the price of those other inconveniences was. And the engineers shortened the ramps’ cycle times. Hmmm.

Dick Day could probably still get his constituents stirred up about ramp meters, but he has retired from the legislature. He’s now a lobbyist for the -- ahem -- gaming industry.


Anonymous said...

I'm guessing I'm probably the only person who's going to read this post, but I thought I'd comment anyway.

Minnesotans do not drive like synchronized swimmers. Ramp meters are a complete waste of money. If people didn't drive 45 miles an hour in the left hand lane on 65 mph roads and if they learned how to yield and merge, our highways would be much less congested. In other words, fewer idiot drivers = less congestion.

And less congestion means less time spent wasting gas on the roads with idling engines. Frankly, we need more lanes on our freeways. Minneapolis-St. Paul has a similar population base as San Diego, CA. They have five lanes in each direction meanwhile many of our freeways are still four lane highways.

Tom Roark said...

This is my first critical comment. Thanks.

You're right about people's driving habits. The other day I was briefly behind somebody who was poking along in the left lane on the Minnesota River Bridge on 77. I had to wonder what he thought of everybody's passing him on the right.

I think laws -- and ramp meters -- are made for people who can't or won't make the right choices. Each of us has the responsibility for how we behave, but collectively... Count the brake lights that come on in front of you on the freeway. I vote for laws and ramp meters.

If you've read any of my other posts, you ought to be able to write my reaction to adding lanes yourself.