Wednesday, March 2

Filter or Permeate

Proceeding Through This Intersection, Filtering Seems Like the Only Alternative to a LONG Wait, Stuck in Amongst Motorists

First off, two "cycling" terms:
  • Filter - The practice that many cyclists adopt when coming upon a lot of motorists waiting at a red light. It consists of moving forward past all the motorists waiting in line for the light to change. A variation on this practice, which is considered smarter, is to stop one or two cars BACK from the front of the line so as to avoid inadvertently getting hit when the light turns green.
  • Permeable - An area that presents lots of route choices for a cyclist. Grid street arrangements are typically great for permeability. Geographic obstacles such as rivers like the DFW Trinity River or lakes greatly reduce permeability. Some road arrangements also greatly reduce permeability even when no geographic obstacles exist.
Way back when, until April of 2009, I rode my v1 commute. The return home usually included a segment northward on Bedford Euless Road that crossed the Airport Freeway (Texas 183) at the bottom of the hill described here. That intersection is the one shown above. The photo, shot today, is more or less typical. My practice at that time was to "filter" forward until I stopped one car back from the front of the line. That would get me across the intersection and into the right lane when the light turned green, where all the motorists that made it through the light would pass using the left lane. The main risk of doing this was that, occasionally, a scofflaw in the right lane would proceed straight through the intersection rather than obey the RT Only markings. Such outlaws were only a minor problem for me, as my routine head check would invariably alert me to the onrushing lawbreaker, and I could simply delay my move to the right until the cheater passed to my right. I try to show the situation with arrows in the photo below, during a break in the traffic. This situation only arose on the ride home. On the ride to work, in the opposite direction, this intersection invariably proved trouble free and I always get through on one light cycle.

The Basic Intersection Arrangement When Traffic Clears Out

However, when I began my v3 commute last November, I that permeability is much nicer than filtering for providing a pleasant ride home. That notion was reinforced earlier this week when, just for the heck of it, I elected to proceed on the old route. Unlike the olden days, I'm a lot more reluctant to filter. Among other things, my motorists can get a little snippy if they have to pass a cyclist for a second time, though the availability of the second lane after the intersection makes doing so pretty simple and most of the motorists are fairly tolerant. Mostly, I don't filter due to changes in me. Maybe I've internalized the "Same road, same rules," and all that. Maybe I'm simply getting all soft.

Well, to make a long story short, after sitting through two light cycles, I bailed out and moved into the RT Only lane and then made a free right turn onto the Airport Freeway Service Road. That got me back on track, with only a frustratingly long minute delay. If you want to see how long a minute can seem, watch a video of a full traffic light cycle change from red, through green, and back to red. It reminded me of how obstructive a cyclist can seem to a motorist. Even a few seconds SEEMS like forever.

Mostly, nowadays, in my v3 commute, I take a different route, shown below. It is an alley behind the mini mall and bypasses the intersection entirely. What's more, there is no cross traffic, and I rarely encounter any vehicle of any sort in the alley. It's even got smooth pavement. It is, simply put, "permeable." It is possible that Rantwick's mom might approve since it avoids any parking lot nonsense while also getting the job of getting places done. It illustrates the advantage of permeability over filtering. I'm not the only one that has discovered such cool route variations. PaddyAnne discovered a permeable route option here, Keri discovered one here, and even I have discovered such alternatives here and here. On the other hand, as here, not all these permeable alternatives will work out.

Instead of Stressing Out at the Intersection Above, Nowadays, I Just Cruise Down This Permeable Alternative
The Photo Shows Above Normal Traffic at Rush Hour - Usually, There is No Vehicle Parked Behind the Distant Stereo Shop

"How do I get in on the good times?" you might wonder. Well, ask your fellow commuters is one means that might work. Another is to look at Bing's aerial view and Google's satellite view. They may reveal alternatives that will make your commute sweeter and possibly quicker and safer as well.

As for me, does my "permeable" alternative speed things up? Well, actually no. It has the downside of routing me directly past the coffee store of a major coffee chain and slows me down by a full 20 minutes. More if there are interesting blog posts on the free Wi Fi. It IS low stress, at least unless I take advantage of a free refill. Still, one must make sacrifices!

Today, looking down Bedford Euless, I saw a traffic-free red light. Seeing a rare opportunity, I made an unfiltered dash to the light where I was legitimately right at the front of the line, and then swept home via the quickest route. Actually, THAT was a source of an awkward question: "Why did you get home so early, dear?"  "Uh, I rode home really really fast just because I love you, sweetheart. Yeah, that's it."

I didn't let on that I find the combination of a trafic-free intersection and a quick route to be even more irresistible than a cup of coffee from a major chain based in Seattle. Absence of that cup of coffee accounted for most of the early arrival. Some things are better left unsaid.


Anonymous said...

I love permeable-ness! But then, I'm not too concerned with going fast or getting any where on time either...

Big Oak said...

I often alter my route, continuously looking for the BEST way to go. I have a couple bottle necks caused by two rivers (the only bridge for several miles), but the major factor seems to be my mood. Sometimes I vary for no good reason. Other times I take the most direct route.

I am a big fan of permeability, though. And fortunately, I don't really have to filter, since I have several route options that are entirely rural.

Unfortunately, I don't have any commute-stoppers, like coffee shops or bike shops.

John Romeo Alpha said...

Permeability is a key concept for bike commuters. I'm with Big Oak, always seeking the BEST way, which is often not the shortest or most direct route. I do ponder the question of how far off the direct route still counts as permeability, versus wandering so far off track that you can't even claim to still be on your way home any more. If the commute digresses into an S24o, I would understand if the family members reject that it was just an exercise in permeability discovery.

Ham said...

Thought you might be interested in this clip

Steve A said...

Interesting video, especially since I plan to tackle the helmet question in a future myth post.

Just a couple of points. The Jaguar Club REQUIRES helmets during autocross. My helmet was made by Shoei. Also, I used my bike helmet about ten times during February. Mostly all in one day. I have no doubt that it mitigated things. I also used my bike helmet on three occasions when I drove the Land Rover.

Still, there really IS a culture of fear out there and cycling is a target for the fearmongers.

Steve A said...

Clarification that reveals Steve bias:

When I say "used helmet," I meant I smacked it when on the bike, while it merely means I wore it when I drove and didn't actually smack it.

Justine Valinotti said...

I have a few different commute routes. I don't have many permeability issues. The main ones are the Clearview and Van Wyck Expressways. They run below street level, and only a few streets cross over them.

In addition, there are two major boulevards (Queens and Northern) that, in essence, hinder permeability. I not only don't ride on them; I also try to avoid crossing them as much as possible. That makes my commute longer, but more pleasant.

cycler said...

I've basically stopped filtering except under a very few conditions (no parking lane is one). It's just not worth it to thread the needle between cars that could start moving at any moment and the doors of parked cars. I think there's a contradiction between taking the lane, and then suddenly deciding, "well, I guess there is a tiny margin of space for me on the right after all." And it's really annoying to drivers to have to repeatedly pass safely every block. I suppose they could just go slower and go at the speed that the lights are timed at like I do, but that's too complicated for most of them :) I think that Boston riding is probably a lot different from most Dallas area riding in that respect.

Unfortunately we're different in another respect, in downtown we have very few options for Permeating. The cows that laid out our streets weren't fond of straight lines or grids :)
I would far prefer to take alternative routes, but when they exist , often they're made very inconvenient to keep cars from cutting through.
I don't mind going a longer route, but a longer, uphill route with sections where I either have to salmon or walk my bike starts to get annoying. There are places where they have "one way except for bikes" signs but I'm a bit leery of those, as I don't think drivers are conditioned to expect bikes enough for that to be safe.

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