Thursday, January 23, 2014


Doing a bit of reading on Planetizen, on an article talking about sprawl repair. The naivite is a little bemusing. Specifically, the McMansions and drive-thru redevelopment.

Awkwardly, much the low-density street development is not worth saving--cheaper to scrape the site and redevelop then to add a facade of new buildings around it. Likewise, the mansion retrofit is unlikely because doing so would require the cooperation of 8 different property owners--a recipe for failure.

Redevelopment authorities sprung into existence for this single purpose--mitigating the problem of parcel fragmentation through land assembly. (Nevermind that their mis-regulation led them to become engines for cities to speculate in real-estate development).

Parcel fragmentation is a big problem in Detroit. I was talking to Dr. Joanna Ganning, who is an expert in 'Shrinking Cities'. Apparently, for all the Rustbelt cities, it's common for half the city to be a successful metropolis, and the other half of the city to be a run-down ghetto of abandoned buildings, un-maintained streets, poverty and crime. 


Reading an interesting paper on urban form, and the author writes: "City compactness can be measured simply using urban spatial form or morphology: the more concentrated the built-up area, the more compact the city is". Which gets me thinking: How is Compactness different from Density?

Planners have moved away from Density, to some extent, on two fronts. First, the Perils of Average Density, and second that density has no rhetorical value---to harp on density "offers no hope to places that are already built at low densities and unlikely to change". For the built environment is a durable place, and changes slowly. Sometimes very slowly. Roads vanish but rarely, and once the development pattern is 'set', very little can be done to change it. 

But what is 'Compactness"? The word has many distinct meanings, but it fundamentally refers to a measure of area. And therein may lay the rhetorical difference--for density, it's a matter of how much stuff is in a given unit of area. For compactness, it's a matter of what unit of area is needed to contain all the stuff. It's a difference of emphasis--the amount of stuff versus the size of the container. What is 'held constant' in each measure is different. For density, it is the unit of area. For compactness, it is the amount of stuff.

Take two hypothetical cities, with the same population. Pi-town is round, constrained within a circumferential wall. Spiderville stretches out in all directions along major roadways. Yet they have the same land area, and thus the same average density. But their compactness is very different. The length of Spiderville's town boundary is much much longer than the Pi-town boundary. 

For transportation, Compactness is a much more important measure then Density. Compactness is also a measure of the distance between any random pair of points within the city. 

This also brings up the interesting topic of fractal density--a city whose edges are yet more scalloped, more indented, then Spiderville, with little tentacles of development reaching out from the urbanized area. 

Monday, January 20, 2014

Davis Connector

Alternatives are not really that different from one another. Must admit a certain amount of irritation with the numbering system. Temptation is to number alignments, and then sub-set them. Better off is to break the alignment into sections, each with shared points, and name the segments of those shared points.

For example, alignment AAA would share the first and third segments with alignment ABA. If someone proposes an alternate route for the middle segment (or part of the middle segment), it becomes 'C', and the alignment is ACA. And then everyone can play mix and match, until there is general consensus on at least PART of the alignment.

Which it looks like they have. All alignment have from Beck/Victory intersection to...near where I-15 and I-215 merge. North end must be the messy part, given that is where they have de-scoped to a more manageable 'minimal operable segment'.

On the south, they have 3--two a block apart, and one next to the capital. Victory Road alignment isn't going to work unless it's bus. Too many impacts on historic properties. Although it did, historically. In modern times, I think it would be impossible to get a LRT vehicle, and difficult to get a streetcar vehicle.

Corridor 2's South end is ridiculous--too sharp for light rail or streetcar, but connects well to State-street buses. 400w seems simply to connect to TRAX then 300w. The 'loop' on 5a/5b is madness--to much cost/mile for rail. In Bountiful, Alignment 2 is preferred for job access--not sure what the intent of 3a/3b--high density housing? Corridor 6 doesn't get close enough to the high-density residential to make it worthwhile. Corridor 3a/3b are decent, as are 1 & 4. Ideally (for light rail) I'd want the bottom of 4 and the top of 1. Irritatingly, none of the alignments reach South Davis Community Hospital, or Lakeview hospital, both of which are major employment centers.

For mode, the distance (~10 miles) is too far for streetcar. For a 'bare field' city, BRT would beat light rail hands down, but UTA already has the maintenance center and vehicles for LRT, which should make it cheaper per mile than normal. But it's hard to make the call on mode without knowing how much is going to be  exclusive right of way, and where the stations are going to be.  At $30m/mile, and nothing worth stopping for along Beck street, BRT seems like the better option. And thus, alignment 2.

Census' OnTheMap shows a slug of jobs at 500 North and Highway 89 (500w).

Hilariously, someone mentions that they don't want streetcars on their historic Davis County streets....where streetcars used to be.