Sunday, January 22, 2012

The Relentless Reckoning of Space and Time

How far? How fast? Predictable? Visible? Angry? Erratic? Texting? Bald tires? Worn brakes?

"...all mountains are in a state of continuous collapse." -Laurence Gonzales

Once when I was camping with my wife and some friends, we set up our tent at the base of a desert hill of medium height. Once the camp was settled, we began our various exuberant outdoor activities. My wife and her friend J were having a conversation in the tent, where they went to get out of the sun and enjoy a cool beverage. Four of us decided to scramble up the hill which overlooked the tent. I was the last of the four going up. It was moderately steep going, and loose with gravel, so in places we were scrambling up on all fours, and moving in a zig-zag to get around the cactus and rocks that littered the hillside.

I paused to watch the three people in front of me crawl up and over an egg-shaped rock that was roughly four feet in diameter. After the three of them got over it, I crawled onto and over it myself. As I reached the top of the rock, I stood upright on it. It popped out of the hillside like a cork, dropping me onto the gravel and cactus. I slid a short distance down, not very far really, and was fortunate to be able to arrest my sliding fall by grabbing stuff. I rolled over onto my back, looked down the hill, and saw the egg-shaped boulder bounding down the hill, directly toward the tent with my wife and J in it.

It is a movie-like memory of devastating possibility that I will never forget. And there was obviously nothing that I could do, the boulder was accelerating on a direct path, and only would take another second or two to roll over the tent. I believe I yelled out, or tried to, but it all happened so fast in real-time that I am not sure about that. I am sure about the feeling of dread and powerlessness, however.

As bounding boulders do, and purely randomly, it bounced off a small bump and careened off to the left, missing the tent, but making a tremendous racket as it rolled by the fragile cloth shelter. My wife and J piled out, and looked up the hill to see what was happening, and saw me sprawled on the ground below an egg-shaped boulder-sized hole. After I apologized for almost killing them, I inscribed a new rule into my brain for permanent and irrevocable enforcement: never set up a tent in the rockfall zone at the bottom of a hill. That space is dirty with danger, and is not a proper place to put up a tent.

A corollary of this rule, learned on another trip: the space at the bottom of a dry wash or canyon is dirty with flash flood danger, and is not a proper place to put up a tent. Even if you're tired from carrying a pack all day, and the sandy wash is soft and inviting, and the surrounding area is rocky and uneven, the wash is flash flood space, not camping space.

For cycling, one similar and relevant observation that raises more questions than it answers: a certain amount of space all around a speeding car is dirty with danger, and is not a proper place for a cyclist or pedestrian to venture into. This space is not static, but moves with the car, a bubble to avoid. For a car on a three lane with traffic in all lanes, moving 45 mph, the space in front of the car which is dirty in this sense is no less than 100 feet, and can be more than 200, depending on road conditions, driver awareness, driver reaction time, driver proficiency, the maintenance state of mechanical components of the car, air temperature, and probably other variables. Some unknown (to me) space on all sides of a car moving at 45 mph is also dirty, owned or occupied if you will by the car, since it could move within that space in the next time slice t+1 with a momentum similar to its momentum in the current time slice t.

In the particular space of these photos, 44th Street in Phoenix at the Arizona Canal, which is marked as a bike route, and is a popular crossing for pedestrians, runners, and the occasional desert tortoise, the reckoning of space and time necessary to float through these dirty high-speed bubbles is relentless. Right near the position of the ped+dog in the top photo, the sidewalk narrows, and is bounded by a wall on the canal side as it crosses the bridge. Cars and trucks often pass very near the curb as they cross, and it feels very much like a ped, cyclist, dog, or desert tortoise crossing this bridge on the sidewalk is well within the dirty bubble zone. The feeling I get there is similar to that of setting up my tent at the bottom of a mountain in a state of continuous collapse.  

Dog+ped negotiating safe space+time across a river of cars, and a mountain in a state of continuous collapse


  1. Very thought provoking and an interesting comparison.....

    Your heart must have been in your mouth as that rock bounced down the hillside towards the tent......


  2. Just as the dirty space at the front of a car varies, so also does the dirty space at the side of a car. Getting passed at a distance of a foot by a motorist creeping forward at your urging in order to make a right is not scary at all, but five feet can be uncomfortable indeed when it is an 18 wheeler doing 70.

  3. Thank you Trevor. I've provoked thoughts of my own on regarding staying out of dirty space, which will doubtless result in future posts.

    Steve, in part at least, I am considering the approach that the only reasonable way to estimate or assess the size of dirty space is to go for the top end of the range, since so many variables and unknowns are important. The Door Zone, and the ends of driveways, seem to be the spaces I have the most unsettling encounters with motorists instantly moving dirty space right in front of my direction of travel.

  4. 44th Street? Yeow!

    I consider ANY portion of that street, at ANY time after 5:30 AM, to be all in caps DIRTY SPACE. And even BEFORE 5:30 AM, if I'm in the right-hand lane doing about 20 mph headed south just below Thomas Road and I see a set of car headlights two blocks behind me ... I amaze myself that I can hit almost 30 mph on my 40 pound recumbent!

  5. BluesCat, 44th and Thomas is truly a stretch of Aggravated Asphalt. It's exactly like a dry wash, with a wall of mud and debris roaring down it.


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