Tuesday, December 31, 2013

Building the Yellow Brick Road; For Speed and Dependence...and Death

This is truly amazing on many levels.  TxDOT says that the state of Texas has now gone 13 years with at least one traffic fatality every single day.  Every day.  Somebody died on the roads.  That's pretty terrible and unnecessary.

However tragic, that isn't even the worst part of the story.  It is completely believable.  No, the real shame is the complete abdication of fault by TxDOT.  That's the easy and cowardly thing to do when places like Chicago are making explicit goals that no citizen should die just trying to get around.  To live.  That is the very first responsibility of government.  Public safety.

User error.  Not our fault.  Even though other municipalities except the reality that traffic safety and deaths are directly related to the kind of roads and transportation system we build.  Safety improves at lower speeds, with more visual activity happening, narrower roads, two-way roads, when there are more transportation modes available and those modes are convenient, when the driver has to make eye contact or just pay attention, when there is higher intersection density, and more pedestrians.  We KNOW all of these things.

And yet?  Here is TxDOT's response:
Authorities say impaired driving, lack of seat belts and speed are the "big three" reasons for traffic deaths.
Higher speeds.  Well, we know people will always drive as fast as the road is designed for them to go.  How fast they feel comfortable and still in control.  Often, so fast that they feel like they don't have to pay much attention and could even text while driving.  Nope, regulation (speed limits) and enforcement (speeding tickets) are quite impotent in improving safety when the road is designed for high speed travel.

When I first saw the designs for the Hunt Hill Bridge and then TxDOT announced the speed limit would be 35, I immediately knew there would be a speed trap on it or at the base, months before it actually opened.  And it happened.  Why?  Because the bridge is designed at highway standards to go fast.  And that alludes to the deeper problem.  The roads are all designed by set standards, all to encourage fast moving traffic, because somehow in fantasy land that improves congestion or safety.  It does neither.

On top of that, the funding of roads steers more money to bigger roads through the mandatory Thoroughfare Plan system.  Bigger the road, the higher the priority, the more money, the wider it has to be.  So cities, to get their free crack fix of transportation money, are incentivized to 'upgrade' as many roads as possible.  By 'upgrading' the road it 'levels up' on the road hierarchy.  Local streets become collectors.  Collectors become arterials.  Arterials become highways.  As they do, they each get incrementally wider, faster, less safe, with less intersections, pedestrians, street life, or clutter.  All the things mentioned above that improve safety.

Sorry, we gotta protect the jobs and the gravy train.  And those jobs are to kill.  Every day for thirteen years past and in all likelihood on into the future unless drastic, systemic changes are made.  Not the occasional bone thrown to a hike and bike trail through and to locations nobody is willing or able to go.  That only exacerbates the problem while pretending to address it.

Impaired driving.  Is due to car dependence.  See my post on this subject here.  The deadliest cities for drunk driving per capita are the most car dependent.  Detroit, Phoenix, Dallas, Houston, Atlanta, Memphis.  (The deadliest states per capita tend to be the most wide open like Montana...high speeds plus drinking).  Here the problem is also partly due to sprawl, inducing such car dependence.  The most convenient and often only way to get around is by car.  Cabs don't know where to congregate outside of hotels, the airport, and McKinney Avenue.  And transit?  Please.

To some extent the user error is true.  However, it's like saying you must use something and you must use it in an unsafe manner to do mundane tasks.  Like eating every meal with a chainsaw.




Monday, December 30, 2013

3000 Days

As you may know.  I'm not from around here.  Despite having lived in Dallas for 11 years, I'm only now starting to refer to it as 'home.'  Because I'm not a native Texan, that means I have family back where I grew up, Harrisburg, PA (hence my fascinated interest with cities that go broke.  See: Detroit).  So each holiday season I have to go back east which might as well be North of the Wall, inhabited by White Walkers and Wildlings.  Such is my distaste for the cold.

And it tends to mean some time in the car.  I'd love to be able to fly in and train to my destinations, but not all of the households I need to visit are accessible that way.  Woah is me.  Instead, we fly in and rent an SUV (for shame!) just in case there is some bad weather in the Poconos between Harrisburg and New York.  There usually is.  Whilst in the car, you have to pass the time while keeping the driver awake because the driver must stay awake for safety but is typically bored out of their mind.  We played some kind of riddle app.

Most of the riddles were pretty good, but a bit formulaic and thus solvable if you paid close attention to the wording (which works on my fairly underdeveloped listening skills).  However, there was one riddle I was unable to solve.  It's "The Case of the Missing Dollar," which you can find here.  It poses as a math problem.  However, it happens to be two separate math problems and the riddle gets you to confuse the two.  The math works both ways, but it is asking two separate questions (SPOILER ALERT!).  I did the math both ways in my head but couldn't quite piece the logic together required to spell out the answer that it's asking two separate questions.  Frustrated (and the only riddle I did this for), I grew impatient and just demanded the answer.

I was reminded of this riddle over the weekend after I got back in Dallas.  I think I was sipping my coffee and enjoying the short stint of 60 degree weather while watching the Premier League or something or other when an Exxon commercial came on.  It wasn't so much asking a riddle but a quiz.  How long can you charge your phone on a gallon of gas?

Now, logistics aside of how you would pour a gallon of gas into your phone (I don't recommend you try), let's think about what this is really saying.  Which is, I don't know what.  It's intentionally confusing the two things of gasoline for your car and your smart phone, an interconnectivity device becoming the ever-more dependable (and energy efficient) form of transportation (see my piece on this subject).

They're talking about the energy density of gasoline which is absolutely true (so maybe we shouldn't burn so much of it?).  Gasoline doesn't power phones.  Gas powers cars.  Your phone is charged by electricity which comes from coal, or nuke, or wind, or some combination of those and other sources of energy depending upon where you live.  However, your phone isn't transporting you and the thousand pound metal cage around you several thousand miles a year.  These two things are fundamentally incompatible and often times at odds (see: texting and driving campaigns).

The smart phone is far more advantageous for the walker to coordinate where to meet friends or the transit rider catching the next train (or in the case of Dallas, trying to figure out the convoluted and incredibly inefficient and deleterious-to-ridership bus routes).  So while your phone might be able to be powered for 8 years or so if you have a gallon camelback filled with gasoline on your back and somehow plugged and combusted into your phone, is that gasoline really that efficient when all it (and the roads we build) is make us drive more.

Let's think about that gallon of gasoline, its efficiency, and the cost for a minute.  Let's say you're like the average American and you commute about 30 minutes each day to and from work.  If you're in Dallas, safe to say that is probably all on highways because the system is designed as a funnel limiting choice and mobility.  So if you're lucky you're going about 60 mph.  That means you're travelling about 30 miles each way or 60 miles each day.  That's 300 miles each week and if your car gets 20 miles per gallon that's 15 gallons of gasoline you're burning each week.

So that's about a tank of gas meaning you're filling up your tank once a week, 52 times a year.  The national average gas price is about 3.31/gallon at the mo' equalling $2,581.80 per year just to get around.  Now compare that "efficiency" of gas to a more walkable city that provides increased and improved choices of mobility, including walking and transit that doesn't take twice the time to get somewhere as driving (incidental thought of the morning, if driving is always the most convenient way to get around, your entire city is equally and poorly connected and thus densification is a stage set.).  Both are more energy efficient than that gallon of gas because it ends up using far less energy, which is effectively a tax on the efficiency of the city as a socio-economic reactor.

It's confusing the two math problems.  But maybe that is their goal.  Don't pay attention to the man behind the curtain.  Instead, take their simple math at face value.  Get frustrated at the actual math involved and demand the easy answer (BIGGER HIGHWAYS!).  But maybe that is the goal.  To confuse you and the real issues at hand.  And you wonder why millennials distrust advertising.

Thursday, December 19, 2013

Parking and Dying in the CBD

I took a moment today to crack open an old favorite, Donald Shoup's High Cost of Free Parking.  This book is the bible for parking policy these days and a great reference manual to have around the office library.  What caught my eye today was a table comparing parking quantities in various Central Business Districts from around the world.  However, Dallas was not included.  So I decided to dig up some data to find where Dallas would sit in the table.

The Table charts and ranks these categories:  Land Area of the CBD (in hectares), Number of Parking Spaces, the Parking Area, and Number of Jobs in the CBD.  From there Shoup includes ratios between these various data points such as parking coverage of the entirety of the CBD, Parking spaces per land area, and Parking Spaces per Job.

Now it's worth noting that this data is fairly old.  It's taken from a 1999 study by Kenworthy and Laube.  However, the Dallas data is fairly new, primarily coming from the Parking portion of the Downtown Dallas 360 Plan.  The table of cities however is basically a shaming device for Shoup's home city of Los Angeles, which at the time was the runaway winner for overindulged parking provision.

I measured the CBD (the area within the highway loop) to be about 368 hectares, right in between Houston (392) and Detroit (362).  The 360 study lists the parking count of Dallas CBD at 68,000 spaces, again right in between Detroit (65,639) and Houston (72,797).  The 360 report suggests a coverage of 27%, however looking at their map that seems low.  It's also well below our nearest peers Houston (57%) and Detroit (56%).  Even DC is listed at 54%.  Either way, that figure is far less relevant than parking quantity per area and parking spaces per job.

I haven't been able to track down an accurate number of jobs as of yet, but a number I've often heard is ~100,000 in the CBD, which again puts it in the territory of Houston (303) and Detroit (257)  in terms of Jobs per Hectare (271).  Hong Kong is at 1,713 if you were wondering what the upper limit was.  Canberra and Phoenix offer the low end at 68 and 90, respectively.

In terms of Parking Spaces per Job, this puts Dallas at .68, again in between Houston (.61) and Detroit (.71).  These numbers are quite a bit higher than Tokyo (.04) or New York (.06).  While this hasn't yet been aggregated, I would bet there is a pretty significant correlation between Parking Availability (as measured by spaces per job) to Transit Ridership (or at least alternative transportation).

I'll have to compile that table next.

Tuesday, December 17, 2013

Austin, Traffic, & Behavior: Forget about the Austin part

NPR has a news story that you can either read or listen to rightchea.  The important part is where Tim Lomax from Texas Transportation Institute starts talking (that is, once you get past the factoid about the unused toll road circumnavigating the east side of the city is way underperforming projections and going bust.  I'd suggest using one of those empty eastern corridors as a route for 35 and let 35's existing route be downgraded and function as part of the grid.).

Lomax says that no matter what is done, traffic will always be awful in Austin (lesson 1 - you can't fight congestion.  A city as a fusion reactor for social and economic exchange brings people together.).  Instead, Lomax says that behavior is what has to change.  In his modeling, he said that things began to look less bleak when commutes to jobs dropped from the ~90% via private automobile to 60% (which would make it 2nd in the country for least auto-dependent behind NYC).  Furthermore, the average commute per day has to drop from 20-some miles to about 5 to 7 miles.  In other words, the only way to solve the ghost of traffic future is to relocalize and get people out of cars.  

Here's the missing piece, however.  It is precisely our infrastructural networks that nudge behavior either into or out of cars and further from or closer to where we work.  Austinites drive more than New Yorkers because Austin has 6x the highway lane miles per capita, which limits route choice, advantages outer-lying real estate and relocation decisions, and subsidizes long-trip commuting.

While the market is dying for more real estate in walkable (or at least potentially/eventually walkable) infill locations, why not create some?

Wednesday, December 11, 2013

Book Review so you don't have to...

BOOK REVIEW

I like that the cover graphic sort of reminds of a DNA double helix, no?

I've got another post for today in the works, but before that I want to plug a book I'm currently sifting through which is not suitable for a lay audience.  It is The New Science of Cities by Michael Batty, a professor at the University College of London, the epicenter for emerging theory on cities and city form, a counterbalance to Copenhagen's pragmatic living laboratory towards livability.  This book is graduate level and above.  So unless you want to wade into its 500 pages, just see my next few paragraphs.

There seems to be a rush to quantify cities into something, ahem, quantifiable, which is a good thing as long as you understand that they very may well be unquantifiable in sum or at least admit this science is still in its infancy or adolescence at best.  Batty understands and admits this immediately.  However, UCL and Batty are at the forefront of beginning to formulate a new way of looking at cities and a new way of understanding them, which is rooted in complexity theory.  This is simply setting the foundation, righting the ship which has been for too long facing in the wrong direction, towards anti-city.

I have written and often present this concept as intro to how we need to also be thinking about cities and get over our obsession with the visual.  Godmother of Complexity theory Donella Meadows even explicitly writes that in systems we focus the most on that which matters the least, which is the visual, the sensual, those things we can touch and see.  And it's understandable since those are things are both the most apparent and that which we have the most immediate contact.

With cities, those things are buildings, architecture, businesses, ie land uses, parks, etc.  By doing so, we are in effect trying to build a forest ecology through raking leaves.  So I've used Meadows' hierarchical framework that all complex systems are built upon: ELEMENTS, CONNECTIONS, and PURPOSE.  And there is an inverse relationship between causality and attention.  For cities these same categories can become: BUILDINGS AND USES, TRANSPORTATION INFRASTRUCTURE, and POLICY.  Or as I like to quip: the invisible hand, the invisible arm, and the invisible brain.

The policy is the most effectual but the hardest to change.  Buildings and uses are the easiest to change, but the least impactful on the larger system.  Policy drives infrastructural shape which drives land use and behavior patterns.  They are merely an outgrowth that is nudged this way or that by 1) policy and then 2) the infrastructure following that policy.

So what is policy or purpose of cities?  Any simpler living system's purpose is first to stay alive and perpetuate life.  Similarly, Maslow's hierarchy of needs is does the best job of outlining the purpose and priority structure of cities.  Thus, you'll see that the most "livable cities" are those that may not have the best art or airports or most robust economies, but they're the cities with the broadest base of Maslow's pyramid.  They meet the basic needs of the greatest percentage of their inhabitants.

The key as Meadows shows for living systems and urbanists is knowing the correct place and manner of intervention.  My interpretation for a defined purpose of cities throughout history is an "improved quality of life through choice and opportunity for social and economic exchange."  I've had to add the "choice" part in to what was a more simple and elegant statement because it is vital.  As I've mentioned the science of cities is a race.  And physicists at the Santa Fe institute have begun to change the language of cities to that of a reactor.  And in a reactor, there is fusion.  Two things coming together and creating an entirely new energy or vitality.  Social and economic exchange.  Laughter, ideas, trade, genes.  These are the things we're transacting.

Such is the language of Batty's book.  Except from his clinical lens, his framework is similar to Meadows' but a bit different.  His three hierarchies are as follows:  FLOWS, NETWORKS, and FORM.  When you begin to unpack the concepts and translate the language between sciences, you start to see the inherent similarities to all of the complexity sciences, which interestingly have a similar godmother in one Jane Jacobs.

FLOWS refers to demand flows or desire lines.  Batty writes that these are a constant.  They are permanent and proportional to a population.  Specifically, these are our needs and wants, which is social and economic exchange.  Buying things.  Hanging out with friends.  Make money to buy things by going to work.  Etc.

Except those things can't all be in one place.  Therefore there is a tension in place that creates a "bipartite" (his word) bond between two things.  There is demand to access these things as efficiently as possible, but not be literally in the same place as all those things.  For one, those things can't all fit in one place.  And two, sometimes you want to get away from those things, such as the bustle of the trade (modern or historic), or more directly, your job.

Interestingly, if we begin picking components of various urbanists throughout time with our modern ability via the internet to take polls and exchange information we start to see increasing relationships between these ideas.  Australian professor Peter Newman's hour-wide city theory suggests that all cities throughout history are about one-hour wide.  You can traverse from one edge though the center to the other in one hour, from the edge to the center in 30 minutes.  What gives size and shape to the city is contemporary transportation technology.

If you look at average commute times across the US, you see that every city falls within a range of about 25 to 35 minutes.  Looking at polls, you see that the "ideal" commute time is about 22 minutes.  Not quite the 30+, but also not too close to work because many want time to decompress (fro) or prepare (to).

That brings us to Batty's next order of hierarchy, NETWORKS.  He writes, correctly in my estimation, that those demand flows between our various origins and destinations are first, abstract.  They exist invisibly.  They are only given shape as they align to networks.  All of a sudden there is a geography in place.  Invisible links now have physical alignments via infrastructure.  The question is how well does a specific city's infrastructural networks respond to these desire lines, and deeper, to our need for expedient and efficient social and economic exchange?

See two examples:






















The road above is clearly not responsive to efficient links between desire lines.  It doesn't enable.  And in fact, it spreads us out to the point (based on car movement) that more efficient forms of movement are nearly prohibited.



The above is 'top-down' designed Rome to the left and 'adapted' Rome to the right, some 2000 years later.  Desire lines optimized the city, maximized route choice and land use premiums by maximizing ratio of interface to land area.

It is the NETWORKS we design and build which give our cities, our inherent need for socio-economic exchange, geography, place.  Whence those networks and in turn places are established, demand driven, then we can practice placemaking.  The building, shaping, and programming of of places to make the FORM of cities that we operate within, love, and remember.  Or don't.

To optimize the greatest invention (and reciprocally the tool and enhancer of civilization), our cities, and their ability to meet our needs without expensing those of the future, (in other words, our ability as an complex organism to perpetuate life), we have to understand cities for what they are, a tool for improving quality of life.  In turn, we have to set our policies as such and align them in such a way, at every level, to maximize the ability for one and all to enhance the lives of one and all.

For now, we'll just build some bigger roads then.  That policy is king currently.

Wednesday, December 4, 2013

Mayors Innovation Project

Apparently there is a group in existence called the Mayors' Innovation Project, which defines itself thusly:
The Mayors Innovation Project (MIP) is a learning network among American mayors committed to “high road” policy and governance: shared prosperity, environmental sustainability, and efficient democratic government.
More relevantly, they've recently(?) released a report entitled, ReThinking the Urban Freeway.  Feel free to click at your leisure as I call out a few important bits below (HINT: they cite ANewDallas).  However, I do have to take issue with the use of the word 'urban,' which unfortunately has lost much of its meaning.  Urban is not merely a geographic location.  For example a freeway running through the middle of a city is not 'urban,' but an Inner-City Freeway (and freeway shouldn't be freeway but highway since nothin' more expensive than free).

A freeway is inherently disconnective by nature.  It makes places around it less walkable if not unwalkable entirely.  Further, it disaggregates people, their neighborhoods, and the economies of place.  "Urban" is about free and easy social and economic exchange.  The highway makes that not free nor easy.  Therefore, using Lewis Mumford's terminology it is anti-urban.  That's why we use Inner-City rather than Urban.

Now, to some of the interesting bullets therein:

  • The by-product:  New commercial activity shifted to outside the city boundaries to isolated strip development accessible primarily by the automobile and not integrated into neighborhoods.
  • Important note: Urban freeways occupy valuable real estate without contributing to the tax base, while increasing blight and decreasing property values nearby.
  • Indeed: Freeways in urban settings were designed to focus on throughput rather than promoting the city’s economy or connecting travelers with destinations within a city
  • True: The construction of freeways did notorious damage to neighborhoods, and had a disproportionate impact on neighborhoods that were primarily African-American and/or low income
  • I can't believe it's not butter: The American Society of Civil Engineers estimates the US surface transportation system needs a total of $1,732 billion in investment to restore it to good condition – and that we need to invest $20 billion for bridges and about $170 billion for urban highways every year.40 As the gas tax declines and transportation funds become scare, that’s money we don’t have.
  • This is new and interesting information: truck traffic also has a measurable effect on residential property values. One recent study estimated that a 1 percent increase in truck traffic on an urban freeway results in a 0.5 percent decrease in property values for homes 100-400 meters from the road
  • Also had never found property valuation data from Big Dig before: In Boston, MA, increases in value of commercial properties along the former Central Artery outpaced citywide increases by more than 30 percent

Tuesday, December 3, 2013

Complexifying the Street Grid

There is a post up over on blog-friend Strong Towns that is getting quite a bit of linkage play about differentiating street grids based on geometric size of the block pattern and the ratio of the quadrilateral "private" developable block and the size, scale, and amount of public infrastructure that inter-meshes with that private space.  Here is a graphic the Atlantic Cities used to demonstrate the difference between Portland  (left) and Salt Lake City's (right) grids



Beyond just the visual geometries, they went a step further to show the relationship between public space and private space.  The implication being that less public space is better.  After all, if we're going by some definitions of urban design, the entire practice (of design as well as governance) is about maximizing private utilization of land through the layout and design of public space and the conduits through which the economy happens (ie roads).  In general, that would be the least amount of public for the most amount of private.  However, that is not always the case and there is no performance measure based on this except that Manhattan/San Fran are low.  Those cities are in high demand and thus high value, therefore...good.

However, the connection is pretty loose.  Both are on the water where land supply is restricted.  Furthermore, can we definitively state that the inherent efficiency of the street grid had much to do with the various local economic sectors are in hyper-drive due to that singular efficiency?



This is an interesting development in the quantitative understanding of cities, but it is only one sub-set and there are far many more factors to also be considered that do play a role in the qualitative function and behavior of cities and those inhabiting them.

SHAPE and REGULARITY
First and foremost is shape.  This measurement only works if the grid is highly regular, uniform, and repetitive.  While it was used in a number of American cities simply as a quick and easy way to survey and convey land from public to private hands for development, many more are highly irregular, change shape and size, and/or vary angles.  See: Dallas.

And Dallas (at least historic Dallas) is fairly regular in that it still has gridiron forms.  There are also the irregular medieval-ish patterns such as in Boston, the Baroque-ish patterns of DC, and the exceedingly highly irregular, oft-curvilinear patterns of cul-de-sacs and sprawl.

I don't want to get into a debate of the merits to the grid vs more irregular shapes.  Because in all likelihood there is no objective right answer nor definitive metric for concluding such a debate.  Either way that decision is generally best determined locally, if not hyperlocally at the actual site and determined by geography.

Which brings me to another way to measure cities that is not dependent on grids being highly regular.

INTERSECTION DENSITY
Civil Engineering Professor from UConn, Norman GARRICK (ed. I mixed up Mailer and Garrick into Garrick.  I'm getting old.) has pioneered this work which is more translatable across the various geometric patterns of all of our cities, which is intersection density per area, typically square mile.

[sprawl+vs.+grid+copy.jpg]

Typically, the grid has higher intersection density than the loopy doopy model.  So what, amirite?

Well, it turns out that Gailer's work actually has performance based results.  Once intersection density gets above 225 intersections per square mile, safety improves (there may not necessarily be less traffic accidents, but they get less severe and therefore, less deaths and severe injury or damage) and walkability increases, including higher mode share for all forms of transportation.



 I explored this locally in Dallas and showed that some of the most depressed areas of the city are that way because BIG infrastructure was introduced, thus reducing intersection density, thus reducing connectivity, which thus reduces opportunity, which then leads to disinvestment and decay.  That sounds complex, but it's actually quite simple.  It's the chain reaction (plus many of the biases that we overlay upon these issues) that makes it seem more complex than it is.

There is plenty to be said about the benefits of high intersection density vs low in how it alters behavior as well as real estate values and patterns.  This is something I'll be exploring in detail in a future post called the Funnel vs. the Filter.

However, this too is still a fairly simple arithmetic that doesn't say much about one-ways vs. two-ways, the scale of the streets in question, etc.  Intersection density does however play a role in another issue that is not taken into account...

FRONTAGE PREMIUM
All land within a block is not created equal.  In a post entitled the value and efficiency of small street and block structure (which, yes, implies high intersection density), I explore the hypothetical notion that 'storefrontage' is worth more than 'storehouse'.  In other words, the land at the perimeter of the block is worth more per square foot than the land interior to the block.  And this goes for just about any high intensity land use, whether that be office (the boss gets the window), retail (the 'lures' go in the shopfront), or residential (where you're often paying a premium for views while the unleaseable square footage associated with storage units, corridors, elevator shafts, etc are relegated internally).

I say hypothetical because the value increment between storefront and storehouse is in all likelihood also highly localized, a variable that changes not only from street to street but from city to suburb and city to city.  Who knows, there may be a relative constant, but oh my the research that would entail.



Ancient Rome vs. Modern Rome, "eroded" to be more useful, adaptable, and maximize value and performance.
Ancient Big Blocks: $46.53 / sq.ft.Modern Small Blocks: $31.5 / sq.ftVerdict: In other words, about a 50% premium for the small street and block structure.
In this scenario, where you have a tighter grid and more frontage you will likely have greater utilization of land and greater overall value.  According to the simple geometric model, Portland comes out looking poorly because its blocks are so small, but that also means a greater proportion of private land is higher value 'frontage' in relation to the sum total of private land because the depth of that gradient premium is a relative constant. It's the tightness of the grid which enforces a discipline upon private development.

CENTRALITY
Lastly (but certainly not last since there is no end to the potential ways to measure cities), there is the concept of centrality or the centeredness of something with regards to its surroundings.  This has some relationship to intersection density.  However, it could be argued that the intensity of the network is a response to centrality.  Greater demand to be near a 'centered' point of gravity creates demand for tighter grid and more streets.  Space Syntax is measuring this concept with their spatial integration models:



You may recognize the above map as London.  These spatial integration maps were used in the planning of the London Olympics, and were striking enough to director Danny Boyle, that he recreated them as part of the opening ceremony.  THAT was London.  Real London, evident of the beating heart of social and economic activity occurring.

What spatial integration maps do is measure the degree to which things are connected, allowing the definition of centers of activity to emerge.  In turn, understanding the direct relationship between movement, accessibility, and value.  The researchers that advanced this mathematical understanding of cities have shown the direct relationship between high degrees of connectivity (real connectivity) with land value, walkability, and crime reduction.  What they're showing is the direct impact infrastructure has upon real estate patterns, ie performance.

Utilizing this model on this side of the pond, I took the spatial integration software and applied it to resilience scientist Eric Klinenberg's work in Chicago to show why similar demographic profiles reacted so differently to catastrophic events, ie performance.  What happened is changes to local infrastructure networks severed physical networks which in turn severed social and economic bonds, the glue of resilience.  A neighborhood center was decentralized and in turn it ended up killing its function as a neighborhood center, which had the unfortunate butterfly effect of eventually killing many people during the Chicago heat wave because of the severing of connectivity and local centralization.

CONCLUSION
So what does the grid actually say about our cities?  Less than we think, but also probably more.  We just haven't put all the right metrics together yet.  But saying low public space to highly private space is a dangerous oversimplification that needs to take performance measures into account.