Archive for March 17th, 2010

Photo by Wavy1/Flickr

To all the myriad distractions cataloged in the life of the modern driver — buzzing Blackberries, rogue McNuggets, squalling toddlers — I would like to suggest another: Birding while driving.

The twin gerunds, though mellifluous to the ears, jar the mind, like some wrong answer on an SAT test: Which of these is not like the other? Indeed, driving is, in many ways, inherently hostile to the life of birds and the activity of watching them. Roads sever and reduce landscapes, while the roar of traffic harms birds’ ability to breed. Driving is a fast-paced, necessarily fleeting endeavor that conquers space through time and distances a person from his environment. Birding is slow, quiet, contemplative, rooted in the natural life of a place. “Driving is not birding,” sternly counsel the authors of The Ardent Birdwatcher.

And yet there are moments when these two activities cannot help but conjoin. There is the sheer volume of roads in the world; one is rarely more than a mile away — as the crow flies — from a road. There’s the sheer amount of time in traffic, often on the way to some avian assignation. Then there is the puckish adaptability of birds to seemingly hostile environments, like the crows who drop nuts into traffic, watch as the cars crack them, then wait for the pedestrian walk signal to descend safely into the crosswalk and retrieve their bounty.

Certain birds flock to roads for roadkill, while New York City pigeons seem apt to congregate in the center of the street — where do those half-eaten bagels come from? — scattering at the precise moment a driver frets he is going to strike them (pigeons, it should be noted, see the world three times as fast as humans, so your 30 mph approach is slow motion to them). And as for the pair of osprey I recently spied, nesting in the highway sign gantry in the median strip on the busy approach to Sanibel Island, Florida, the road provided not only a domestic infrastructure but protection from would-be predators (not even squirrels can climb smooth steel poles).

I first became aware of the discrete pleasures, and not so subtle hazards, of birding while driving on a trip to Trinidad several years ago. I was on a trip with Barry Ramdass, an accomplished local guide, to the Nariva swamps, a birding hotspot in the center of the island. Every few miles or so, Ramdass, binoculars wedged in his Jeep’s cup-holder, would, in a sidelong glance, spy some minor disruption in a roadside grove of trees, or across a far plain, pull over to the shoulder, and point to a distant savannah hawk.

This ability confounded me at the time, but as my own birding prowess has grown, I have come to realize that spotting a bird on the road becomes as instinctual as spotting a traffic sign or a speed trap. Driving past a dead tree is a delicious temptation to scan for a raptor, while a bluebird house posted in a field triggers an involuntary twitch to wonder about its occupancy. An uncomfortable fact arises: The better the birder, the worse the driver. “Car birding,” notes the author of Down and Dirty Birding, is birding’s “dirtiest secret.”

David Gessner, who in his book Return of the Osprey admits to birding while driving proclivities, notes that “travel is a precarious point in the lives of both humans and birds.” Perhaps this shared sense of commuting — the word, we should remember, comes from the Latin commutare, “to change” —is the strange appeal of seeing a bird on the wing while my hand is on the wheel. I do not Twitter while driving, but I am hardly immune to the tweet.

(graph by Texas Transportation Institute, via The Infrastructurist)

I was grooving on this almost Ed Ruscha-style illustration (”27 Onramp Configurations”?) in a new paper from David Levinson and Lei Zhang, “Ramp Metering and Freeway Bottleneck Capacity,” in Transportation Research: A Policy and Practice 44(4), May 2010, Pages 218-235.

The findings were sanguine on ramp metering:

Traffic flow characteristics at twenty-seven active freeway bottlenecks in the Twin Cities are studied for seven weeks without ramp metering and seven weeks with ramp metering. A series of hypotheses regarding the relationship between ramp metering and the capacity of active bottlenecks are developed and tested against empirical traffic data. The results demonstrate with strong evidence that ramp metering can increase bottleneck capacity. It achieves that by:

(3) and increasing queue discharge flow rates after breakdown – the average queue discharge flow rate is 3 percent higher with metering than without (with a 3% standard deviation).
Therefore, ramp meters can reduce freeway delays through not only increased capacity at segments upstream of bottlenecks (type I capacity increase), but also increased capacity at bottlenecks themselves (type II capacity increase). Previously, ramp metering is considered to be effective only when freeway traffic is successfully restricted in uncongested states. The existence of type II capacity increase suggests there are benefits to meter entrance ramps even after breakdown has occurred. This study focuses on the impacts of ramp metering on freeway bottleneck capacity. The causes of such impacts should be more thoroughly examined by future studies, so that the findings can provide more guidance to the development of ramp control strategies. It should also be noted that both types of capacity increases on the freeway mainline are at the expense of degraded conditions at the on-ramps and possibly arterial network. Therefore, without more comprehensive system-wide analysis, the findings of this paper, though in favor of ramp metering, do not necessarily justify its deployment.