The map will be on the presses shortly and should be ready for distribution by the end of August. I had actually finished just before I left for Europe a couple weeks ago, but there was a little trouble with the folding that delayed things. I had to wait until my new (European) phone plan kicked in to let me call my partner who is now working with the printer for me.
That link up there goes to the folder where I’m keeping the most recent raster version of the map for the printer. It may yet be updated a teeny bit. PLEASE NOTE that the color is not optimised for RGB yet. I designed this for a specific printer/paper and, trust me, the colors look better on paper. You can get a bit closer to seeing the actual color of the map by looking at this image. Once I get back home and back to my desktop computer, I’ll be able to work on an RGB color-corrected PDF version for the web. I thought y’all might like something to look at in the meantime though :-)
Also note that there is a 1/3″ bleed included in those images which will be trimmed off. That too will change in the PDF/web version.
I can’t wait to see these little buggers finished! ^-^
Third day in England here. So far I’ve seen: Derby, Nottingham, Sheffield(just a little) and Manchester. Also, some the intercity trains, and various local transit.
The good news: Making a beautiful, functional, pleasurable city doesn’t seem all that hard. They’re doing everything planning theory says to do, and it seems like it works beautifully.
The bad news: Cincinnati doesn’t seem capable of doing nearly everything right. Rather, it insists on doing most of it wrong. Has done for a while now.
Evidence: There is much more going on in downtown Derby (pop=~300,000) than there is in Cincinnati (pop=~2,200,000). For real.
The upshot: I’ve decided to get the hell out after I graduate this time. This has been a dry tickle on the back of my throat for a while now, but I stopped short when I got to Manchester and it rolled to the tip of my tongue.
Two weeks left in the trip! Let’s see how this little nugget tastes by the end of the month.
931 miles that go nowhere, versus 2,761 that offer escape from either end.
For bikes at least, not that routing for other modes would change the figure much. Fun/disturbing fact of the day! Impress your friends with your amazing and mathematically informed knowledge of Cincinnati geography!
I talked about this geography of connectivity thing a little bit already, but since that post, I’ve switched to a better dead-end-finding algorithm. Where before I was looking for tree-like structures by recursing on nodes with only one edge, I’m now able to detect all nodes which could be removed from the graph‘s largest biconnected subcomponent by the elimination of just one edge. Or those which are already detached, of course.
In layman’s terms, this answers the question: “Where should we put no-exit signs?” Or for the purpose of defending our titular statement: “what portion of streets, measured by their length, would be behind such signs?”
Here is the PHP script I wrote to implement the algorithm. It connects to a PostgreSQL DB, and looks at a specified edge table with source and target fields. (These source and target fields are the IDs of the nodes on either end of the edges.) You can create an edge table, as I did, using OSM data processed with osm2po. Since I was routing for bikes, I excluded highways and most trunk roads. I also excluded dangling service roads from the measurement.
As the script runs through the graph, every time it isolates a subcomponent, it inserts the nodes of that subcomponent into a temporary table, along with a unique ID value for the component. Once all the nodes are in there(technically, they’re all part of some subcomponent), a GROUP BY statement gives us the ID of the biggest component. This component is the main street network itself. All edges that touch any node that is NOT part of this largest component are identified as dead-ending.
Before altogether too long, I’ll get around to doing some more interesting analysis and regional comparisons and mapping and stuff. But for now, I’m off to Europe with my little netbook, which is, to my honest delight, too puny for serious GIS.
What is a bike friendly destination? At best, a bike tolerant destination in a sea of petrol-stinking crap. What is a transit friendly destination? A place with people inside its monstrous machinations.
I hear through the grapevine that people are now collecting economic statistics on the recent development of Over-The-Rhine in an effort to demonstrate ‘the economic impact of the streetcar’. My contention with whatever they will is obvious enough that I feel silly making it but yet the folly goes forward rather oblivious to my mind.
The Streetcar doesn’t exist yet, people. Let’s cool down the propaganda machines.
What might be measured by and interesting in their report is the development of a neighborhood in rapid transition for any reason. What cannot be evident is the effect of a project not yet realized, unless we consider it only as a local, government outlay in which case we may as well have set to work digging ditches of a more ordinary sort. The effect they intend to measure, though they won’t put it in these words, is the effect of their own boosterism, a fully psychological impact. They want to show us how big their bubble is.
Please, all of you, do the spirit of rationality a favour: if you hear someone saying the streetcar is already, clearly, making OTR better, point out that the streetcar has never yet been seen to function. Demand serious analysis for claims that any one thing has dramatically effected something so complex as a whole, urban neighborhood.
So much time talking about the bike map, so little time showing what I’ve actually been working on. Usually it’s the other way around: all showing, no talking. I thought I might wet the collective hydrostat, prior to it’s ultimate aid of more thorough public digestion, with something that my more tiresome colleagues might call an image which conveys brand equity.
Soothing or perhaps jarring colours, a sense of immediate tangibility, not less than a touch of fetishism. The object or better it’s image becomes a site of worship. White-balance is of the utmost importance. Perhaps I’ve been in DAAP too long already today? Perhaps I shouldn’t work in this library any more.
But just look at that underscoring shadow!
On a less sarcastic tone, I’ve finally finished a task of which I’m rightly proud, which no one knew I was doing: detecting dead-ends successfully after a four day expedition into graph theory. Robert Tarjan is the guy to thank here, and the Wikipedia editors who tediously provided a pseudo-code implementation of his algorithm for the detection of strongly connected network components. The bike map will emphasize only one strongly connected network component, the biggest one, and all the rest will be damned to transparency!
Or more simply, the idea is to deemphasize streets which don’t go anywhere. There are a surprising number of them!
The goal right now is to have the map on the presses by the end of July, to be distributed near the end of August when I return from vacation. I’ve got a little surveying and data entry left for me in the days ahead, and then the big crunch as I finalize the layout and systematically double-check important features.