Friday, June 28, 2013

AIA Presentation

Here is the powerpoint I gave to Dallas AIA last month (excuse the fonts and animations getting a bit whacky in the translation to slideboom):

Wednesday, June 26, 2013

Commuting Time Correlation and the Commuting (In)Efficiency Index

I came across some new data today that I didn't currently have in my Metropolitan Statistical Area (MSA) infrastructure - density - highways - mode share database mashup.  It was average commute time, which I had begun, but didn't have a full array of data to begin making any charts.  Here are those charts.

What I wanted to find was whether there was any correlation between a variety of statistics in relation to commute time (that are actually quantifiable and quantified), such as what role do things like density, congestion, highway infrastructure, etc. have on commute times, if any.

My hypothesis was that the correlation would likely be very low, as I expected that commute times had more to do with job to housing balance by location.  Knowing cities, you know that jobs and housing tend to co-locate in relation to each other, as (somewhat) evidenced by Prof Peter Newman's hour-wide city theory stating that no matter the transpo technology of the day, a city is always generally an hour wide from end to end and 30 minutes from end to center.  The market simply doesn't put up with much more than that.

This jives with surveys searching for the ideal commute time, which tend to be about 22 minutes (though that would be below the average commute time in every city).  The reality is there is an equilibrium where people like to be a certain amount of time from their work, enough time to prepare for the day mentally on the way to work and enough time to decompress on the way home.  Too close or too far, could disrupt this seemingly necessary transitional mood or phase shift.

Onto the charts.  Let's see if I can structure them in an order that makes sense:

Let's start with the simplest.  Distance traveled daily to commute time (which will show up as one axis in every chart):

Nope. That's all over the map.  Distance has little to do with time.  Which makes a good bit of sense, since distance here isn't factoring mode.  Way too many variables still in action.

How about Density to Commute Time:

Also all over the place.  Again, this doesn't factor mode.  The availability of a 20-minute walk is no different than a 20-minute drive of a lower density metro here.

How about to total driving, ie Vehicle Miles Traveled per capita to commute time:

Any correlation here is extreeeeeemely minimal.  Though a slight, very slight, negative correlation.  The more people drive there is a slight tendency towards shorter commute times.  But that's a stretch.

How about highway capacity to commute times:

Slightly more of a pronounced pattern, perhaps building on the prior.  The more highway lane miles, ie capacity, the shorter the commute.  The theory being that it's a clear highway for you, the faster you move.  This is TTI's ideal scenario (I had a less appropriate analogy here, redacted).  However, you'll see the R-squared factor is quite low.  Also, the shortest commute time (Kansas City) also happens to have the most highway capacity.  Remove that dot way up in the top left corner, the correlation starts to disappear.  Can we really count on a relative outlier as justification of correlation?  I don't think so.

How about Congestion to Commute Times?  Theoretically the more congested a place, the slower traffic would move compared to ideal speeds and travel conditions.  In this case, I'm using daily highway traffic per lane mile per capita, ie traffic over capacity.

Again, some verrrrry slight correlation that increased congestion equates to increased commute times.  But this must also be taken in context of the idea that increased congestion correlates (more strongly than this) with increased economic activity.  Trade-offs is the theme at work here.

How about travel mode:

Oooohhh.  Now we're starting to see some patterns emerge.  The increase non-vehicular commuting mode correlates with increased travel time.  This makes some sense with the potential waits between headways of various forms of transit.

But what if we take NYC out of the equation?

The correlation drops a good bit, R2 dropping from .46 to .30 though that is still stronger than anything else I've compared (and many didn't even make this post).  However, there is still a potential lesson here and again, that's in trade-offs.  People are willing to take alternative modes of travel if the time of commute is slightly longer.  Why?

My guess is because of the potential benefits of alternative modes of travel, whether that means living in a more dense, vitally active place, the amenity of increased choice availability, increased productivity -- the ability to do other things while on a train for example like read or work, or improved health benefits from walking, cycling, or not dying on the many rush hour crashes each day.

On the surface at least, this quick study seems to confirm the theory that no single variable has a signficant effect on commute times more than the natural equalizing force towards that standard 25-30 minute commute.  The better, or more interesting question might be, is a shorter average commute preferable or even worth pursuing, if that isn't the market's preference (provided it doesn't create infrastructural and energy inefficiencies in relation to the diseconomy of decentralization).

While playing around with this data I started thinking about new mash-ups.  Here's one that I call the Commuting Efficiency Index.  Or in the case of some cities, the Commuting Inefficiency Index.  It adds Average VMTs (as proxy for extra energy expended by driving over increased distance) to Average Minutes of Commute.  The thinking here is trade-offs.  Some cities could be better at less driving/distance/energy consumption while others could succeed at quick trips, like Kansas City (though this doesn't measure KC's big weakness which is infrastructure to tax base deficiency):

3 Most Efficient Commutes:

1.  Portland  43.6
2.  Sacramento  44.6
3.  San Diego  46.7
All West Coast.  Interesting.

3 Least Efficient Commutes:

1.  Houston  61.0
2.  Atlanta  58.2
3.  Orlando  57.2
All Sun Belt.  Interesting.

Just about every other city is pretty tightly packed between 49-53, but those six stood out quite a bit beyond just being top three on each side of the spectrum.

Tuesday, June 25, 2013

Meeting CPH Accord Through Releasing Pent-up Demand

This weekend I read an article about how the US is falling well short of targeted goals for reducing CO2 emissions according to the Copenhagen Accord.  The numbers actually aren't that far off.  We are and are projected to remain around 5.5 billion metric tons of CO2 emissions.  Our goal is to get down to 5 billion.  Later today, President Obama will announce plans to reach that goal.  I don't yet know what will be in his plan, but here's how it could be accomplished much more easily: Walkable Urbanism.

Let's run through some rough numbers shall we:

According to David Owen's book Green Metropolis, the average New Yorker (as in the city) produces 7.1 tons of CO2.  The average car-dependent American produces 24.5 tons.  (He uses Vermonter as proxy).  That's 17.4 less tons of CO2 per person between walkable/transit-oriented vs. unwalkable car-dependent.  And we need to shed 500,000,000 tons.

Dividing the 500 million number by the difference of 17.4 equals 28,735,632 Americans that, if they were to move into more walkable neighborhoods, could save the entire surplus of CO2 we're trying to shed by 2020.  That's 10.78% of the country at a time where, according to surveys, there is a pent-up demand gap of closer to 40% between those that WANT to live in walkable neighborhoods and those that ACTUALLY do.  We'll revisit that point in a bit.

But we have another complication.  That calculation assumes population levels remain stagnant.  But they're not expected to do so.  By 2020, the US is expected to have about 337 million people.  Up 27 million from the approx. 310 million we have today.  That's more CO2 we have to get rid of.

For the sake of math to determine what percentage of the country needs to be in more walkable urbanism to hit the CO2 goals let's assume all 27 million of that growth moves into walkable urbanism (thru walkable development patterns alone - this is an exercise to see what's possible.  We should be pursuing all market-based strategies imaginable to some degree).   Plus the 28.7 million that will have to move to walkable n'hoods, that puts us at nearly 56 million increase.

However, the 27 million are still producing 7.1 CO2 (assuming they achieve NYC levels of output).  That's another 191 million tons we have to account for and reduce.  If we divide that number by the 17.4 reduction from moving from car-dependent places to walkable places, that's another 11,017,241 million who would have to move.  Err, want to move.  Again, more on that in a second.  The total number of people that would have to move from car-dependence to independence and choice provided by walkable urbanism (of all scales and densities) equals 66.752 million people.

The key for this to work, is that it has to be market-oriented.  People have to WANT to move from car-dependent living to walkable neighborhoods.  And the fact is, they do.  The 66.752 million number is only 19.8% of the country's projected 2020 population.  Less than 20% is not a big number, particularly in comparison to the 30-40% of the entire country that wants walkability now, the 70-80% of millennials who desire to live in it when they get the chance, and the baby boomers rapidly approaching retirement and presumably desirous of empowering NORCs, or naturally occurring retirement communities.

These places are more like the Upper West Side, Key West, and Scottsdale than they are the typical retirement community.  Just a guess, but I'd expect boomers will want more from their golden years than the isolation of the typical retirement "warehouse."  This is the Me generation after all.  And frankly more power to them.  But we have to shift the market so that the pent-up demand is profitable and can be delivered.

However, cities take on the shape of the infrastructure provided.  Especially if roads and gas and parking are subsidized to the extent that they are.  And since they are, and built to the extent that they are, they shift the real estate market to favor constant outward expansion, taking land that was previously worthless and giving it a value of 2 out of 10, up from 0 or 1.  And therein lies the profit margin, especially if taxpayers build the infrastructure to unlock it.

Unfortunately, this process of road building rather than city building makes all areas equal, competing on the same plane, equally isolated and disconnected from all things.  Thus, car-dependent.  Downtowns, which would've been a 10 on the scale of 10 as the most connected places are also now more like a 2 or 3, emptying out to reach its new lowered level of amenity and attraction like a glass with a hole punched into it as demand leaks all over the table.

The new system is a diseconomy of wasted cost and energy, the cost of doing business takes a 20 mile car trip just to do anything.  The advantages of urbanism have long ago been tossed out with the bathwater.



The above map is Madrid, Spain.  Except it is overlaid upon an aerial of the DFW area at the same scale.  (note:  I flipped and rotated Madrid to more closely match DFW's growth pattern from the central core.  You'll notice the airport is actually to the north-northwest of the city.)

I chose Madrid for a variety of reasons.  It's landlocked with an unnavigable river.  It has a similar hot, dry climate to DFW.  And the entire country's per capita CO2 emissions are similar to NYC's: 7.4 to 7.1M.  But primarily because it's metropolitan population is virtually identical to that of DFW, 6.3-6.4 million people.  The red part is Madrid's central core.  Orange is the remainder of the city of Madrid (populated areas only) and the yellow is the remainder of the developed areas of the entire metro area.

It may be difficult to tell at this smaller scale (you can click to embiggen), but the entire city of Madrid (3.3 million people) fits inside of Loop 12 (with plenty of green space to spare).  Nearly the entirety of the metropolitan area fits inside of 635.  Not all of DFW even fits on the map above.  McKinney, TX is cut off by the top of the map.

I also chose Spain because many of their suburbs are true to the definition of that word.  They still have the characteristics of urban interconnectedness, but are lower on the hierarchy of nodes and centrality within the larger urban network and to a lesser density.  Those two things are directly related.

As I wrote about Valencia's pueblos here and here, Spanish suburbs are still remarkably walkable, typically connected to the cores by a train station and a highway that are both meticulously protected against from negatively impacting housing.  However, the industrial sites are typically zoned and cordoned off on the other side of these regional, large-scale shipping routes.

Madrid and Valencia also offer some great lessons in what not to do for your city as well as much broader economic stories about Spain in general.  The Madrid metro is pockmarked by dozens of mega developments that are little more than street grids and a few, mostly empty, mixed-use developments.  They built (and the banks lent) development without the suitable growth to justify the development.  Valencia, well they spent about $2 billion on this, which by some measure is the dullest part of the city.  The anti-city within the city.

I show this because it can be used as a proxy for what would DFW look like if a much greater number like 60%+ demanded and followed through with moving into walkable urban neighborhoods.  We only need 20% to reach our goals.  Now if only our DOTs, ironically the most powerful force shaping cities yet the most ignorant as to their own impact, could recognize the effect they have on shaping and/or pending up the liquidity of housing and market demand.

Thursday, June 20, 2013

345: The Burial







As for economic development, let's look at a comparison table.













How about highway capacity at the city level:












Lastly, more highway capacity means we drive more:

Above shows how more infrastructure means more driving.



Monday, June 17, 2013

Contemporary Design in 5 Easy Steps

Created by Marc Szarkowski(?). Click to embiggen.

Anytown, USA's Worst Intersection



Friday, June 14, 2013

TxDOT and the Ministry of Truth

TxDOT has put out a notice of public meeting for the US75 corridor (not 345 - but everything north):

There are a few incredibly misleading statistics they cite which seem to serve little purpose but to incite fear and acceptance.  The first is that "if left untreated traffic will rise to 420,000."  That would make US75 the busiest freeway in the entire country.  Busier than the 405 in LA which, by the way, has been shut down for entire weekends at a time during "Carmageddon" without crippling congestion or the literal end of the world.  Nor LA.

Furthermore, since no highways in the country actually move that many cars per day, you can reasonably assume that there is a carrying or tolerance capacity at which point traffic becomes too intolerable and drivers go a different route, carpool, take transit, and over the long-term the real estate market shifts to favoring proximity. Business move closer to residential, residential moves away from the busy highway.  In other words, there is very little probability it will ever get that congested.

Lastly, as for that congestion, to wit TxDOT says congestion on US75 costs drivers $80,000,000 per year.  That sounds like a big number.  Until you dig into it.  When you take those 230,000 cars per day over the course of the year that congestion equals 95 cents per day (less than most tolls) or $347 per year.

This is called the cost of commerce.  Now compare that to the cost of car dependence which equals $6,800 per year per capita, specifically due to the highways that fragment and divide our communities, neighborhoods, and businesses coercing us into our cars.  We lack real choice as evidence by our 95% car commuting statistic surpassed only by Detroit amongst major US metros.

Based on Victoria Transportation Policy Institute, Texas Transportation Institute, and USDOT/census data, congestion costs the US just under $400 per year per capita for all roads.  In other words, that's 1/2 of a DART local yearly pass or 1/4th of a DART regional yearly pass.  It is insignificant and uniform throughout the world.  Congestion can't be defeated, only worsened.  That TxDOT's work is putting all of us into cars, thus congesting the roads, thus guaranteeing the need for them to widen the road.  Wash, rinse, and repeat.

Also, keep in mind TxDOT is asking for an additional $2billion per year over their existing $2billion/year budget despite about $18billion in debt.

The problem is demand-sided.

Thursday, June 13, 2013

Bend the Spoon, Bend the Road, Bend the Future



Below is what 345 tear-out would do:




OK. Now what? 











Museum Tower....AGAINNNNN....



Wednesday, June 12, 2013

All the King's Cars and All the King's Scribes

Time for a fisking.  Perhaps if only because the entire thing is written with the shockingly unprofessional, patronizing tone of someone imbued with the confidence of being the mouthpiece of autocracy (journalism!). So bear with me a moment as we unscroll the King's edict and graffiti on his hand maiden's calligraphy.
Let me tell you about this blogger I pay attention to and what he calls his “recurring fantasy” about tearing out a major freeway that goes right through the center of town.This guy writes a bit about transportation and has an eye for other community affairs I follow, like politics, city hall and development. In recent months he’s referenced highway tear-outs in other major cities, and wonders why it can’t happen here, especially since TxDOT is now studying options for improving, fixing or replacing this stretch of road.The freeway, he says, is an artificial barrier that chokes off the edge of downtown and divides the city. The freeway in question is North Central Expressway in Richardson, and the writer is Mark Steger. He would like to see Central disappear and replaced with a “boulevard that’s people-scaled” and a grand central park that would invite development alongside.
We're not espousing tearing out freeways in the suburbs because the suburbs are built on the logic of the freeway.  They are dependent upon them, structured around them, and the growth is adapted to them.  This is why we bothered to dig up the Presidential memorandum quoting President Eisenhower.  There is a key distinction between intra-city highways and inner-city highways.  As Jane Jacobs wrote, big infrastructure is for going to big places.  You take the highway TO Dallas from points yonder.  You take city streets TO your job, to the store, to small destinations from small destinations like your home.  You don't take highways THROUGH cities, which end up being destructive to the fine-grained networks and urban fabric of social and economic connections of streets and blocks.
I’m sympathetic with the impulse, since it’s hard to love a freeway, especially this freeway. I live about a half-mile away, and the traffic translates into a constant low-level white noise that rivals the crickets in my backyard. I see the poor souls stuck in rush hour traffic there every morning on my way to the DART station to hop a train heading downtown. There is nothing aesthetically pleasing about the businesses lining the service roads.
The aesthetically displeasing buildings along the freeway frontage roads are a direct outgrowth of the highway.  The form follows the function of the street and that function is dangerous and repellent to people, thus the need to barricade buildings away from the freeway with distance and parking.  Unfortunately, when you build highways and get highway side development the tax revenue of a typical suburban style development (let's say a walmart) is about 1/10th of that of a typical walkable, urban mixed-use development.  So here's the equation, low tax base, low density, but more tax burden by way of infrastructure to support the low density.  It's an equation doomed to fail.

Could this possibly be why cities are systematically pulling out freeways?  Or that Vancouver, Paris, and London prevented freeways from entering the city.  They won't stand for suburbanites taking advantage and thus destroying the goose that lays the golden egg.  That city fabric that everyone loves and generates wealth.  Please do remember that cities have existed throughout the history of civilization as the platform for improving and advancing quality of life.  As Lewis Mumford wrote, highways make for anti-city.  His words make sense theoretically since traffic engineers one and only goal is to move cars, which means defeat congestion.  Unfortunately, it's difficult to share laughs, and love, and ideas, and money when we're all in cars.  Cities are built to bring people together.  That's the definition of city.  Endless points of convergence which we call intersections.
Walking beneath the freeway, I can sense the soot and heat radiating from the 200,000-plus vehicles that grind past every day. The pounding manages to pound one thing into your brain: This is not a road for my neighborhood, nor should I expect it to be. We happen to live along a torrent of regional traffic. It’s not pretty, but neither are airports or landfills or many other facts of urban life. Dallas-area drivers spend an average of 28 minutes or so getting to work. About a quarter of the workforce has a higher pain threshold, and spends more than an hour on the road one way. This translates into freeway demand.
The freeway demand is self-fulfilling specifically because of the freeway system subsidizes sprawling, car-dependent real estate markets.  It was perfectly logical for people to move out of Dallas.  That's the problem.  Only, it's never getting any cheaper, for 1) citizens to drive, operate, and maintain cars and 2) cities and DOTs to maintain the fiscally destructive car-based infrastructure.  Considering we have the highest car commuter rates, thus car-dependence, in the country of major cities, we can reasonably infer that this is not by choice.  We are arguing for increased choice in the way people live and what they spend money on.

However, he does make an incredibly strong argument against having highways in the city, given that a quarter of the workforce spends an hour in the car.  Is that worth it?  For people to spend 
And for that reason my neighborhood freeway isn’t going anywhere. Steger allows as much when he refers to his tear-out campaign as a “Quixotic dream.”
At least, he avers, TxDOT’s exercise in collecting community input can raise the issue of how the next- generation Central Expressway can be more a good neighbor and less of what Steger calls a “road-widening, community-dividing, downtown-killing, multi-billion dollar TxDOT construction project.”
Want to know why so few people show up to these community input sessions and are disillusioned with the entire "public process" charade?  Because they're bullshit when it's about 9 options of the exact same thing. 

Should not city building by self-determined? 

Furthermore, I consider quixotic to be a compliment when juxtaposed within the context of tories suggesting self-government is but a dream.  Yes, we're trying to insert a real level of democratic input and dialogue to an autocratic, anti-city process about what we want our city to be, and even less so determined not by Dallas citizens.
TxDOT’s meetings to collect community input will be next week in Allen and Richardson. I may see you there.
Ah, the public commons in process at a motorside lodge or some such.  I'm truly shocked a journalistic entity would employ somebody that doesn't understand why DART ridership stagnates while we make driving the most convenient possible form of transportation.  But it is they who also put out that atrocious, shallow series on sprawl last year.  
So what’s the timeline for something as potentially massive as a big fix for North Central Expressway, from Richardson to McKinney? If it involved something that I’d recommend — a big dig, like the LBJ project, that puts added lanes below ground and includes sound-reflecting walls — the project probably would not be built in my driving lifetime. The LBJ re-do took two decades-plus to get going.
No. Let's look at a different timeline.  The construction and maintenance is irrelevant (aside from the fact that as long as we have them they are purely a money sink forcing people into cars as they disperse the real estate market away from them, further apart from each other and into cars.

Any talk of building a new highway is thinking 40 years into the future.  So the real question is what kind of city does Dallas want to be in 2050?  What kind will it have to be?  Once again keeping in mind that car-dependent and coerced movement is a tax on both the citizens and the public agencies that serve them.
The idea to make North Central Expressway disappear is not the only freeway pipe dream in the vicinity. 
Yeah, give me that aura of authority veiling the insecurity.
There’s a similar notion to make IH-345 vanish from downtown Dallas. This is the freeway that you end up on if you take North Central Expressway south to I-30.
No. It's not similar as I've pointed out that highways are incompatible with inner cities, but systemically fundamental to places like Richardson.
The background is this: TxDOT has a stressed-out, mile-long stretch of elevated freeway on its hands, and it’s nearing the end of its design life. The design is not one that would be approved today for pounding traffic. It’s just not sturdy enough, from the placement of the columns beneath the structure to the way the decking isn’t bolted down to the cross beams.
Yes, this is why it shouldn't be misaligning city streets causing the assymetric column structure.
TxDOT has been burning through money on upkeep. Just monitoring the bridge for cracks and wear costs about $100,000 a year. Repairs themselves have been between a quarter-million and half-million a year.That led TxDOT to plan a bridge repair or replacement project and a comment-gathering period from the public. Hence the idea arose to get rid of the freeway altogether.
Nope.  We started the work on this two years prior if you haven't noticed.
That’s not going to happen, no more than North Central Expressway will disappear from Richardson. IH-345 is part of the interstate highway system. It serves an average of 170,000 vehicles a day, with a morning traffic pattern that’s similar to the south-to-north rush up Stemmons Freeway in the morning. Southern Dallas and Dallas County commute north past dowtown, you see, filling up I-345, just like Collin County commutes south, filling up Central Expressway. It’s the pattern of our city’s commerce.
First, a pattern that is there because it has been constructed that way around the freeways.  One that also shifted most of the middle class tax base, white and black further away in each direction, but have fun playing that overly simplistic race card.  Forcing the poor to own cars and spend half their income just to get to jobs at highway side drive-thrus.  Second, this plan brings investment and jobs closer to south Dallas, so the commute isn't so long and makes walkable, transit-oriented housing more affordable than the over-inflated prices in the very few walkable places in this city, precisely because of this kind of cheerleading pending up the demand for walkable neighborhoods.

Cheonggyecheon moved the exact same amount of people.  It was replaced with two lanes of surface streets and a park.  Instead of those cars, they now get 500,000 pedestrian visitors per week.  Again, what kind of city do you want?
The surface streets would not absorb the daily migration of that workforce without degrading neighborhoods by transplanting congestion there.
Au contraire.  The majority of the traffic isn't coming anywhere near these surface streets.  The long haul freight and regional traffic re-routes around the city precisely why the perimeter highways were built.  Then, streets like Peak/Haskell, Good Latimer, Cesar Chavez, and Pearl (among others) could be cleaned up from the horrible, spaghetti of streets they've become because of the arterial/highway system, acting as legitimate north-south boulevards.

And no, it wouldn't degrade the neighborhoods that actually need the life since sapped by big roads taking it away from them.  (note: one sentence graph just for the DMN)

Traffic is not a problem when it's properly tamed.  Hence, why we distinguish good congestion from bad congestion.  Champs Elysees moves 80,000 cars.  It also moves 500,000 pedestrians.  Traffic drives value.  Businesses need traffic.  But it needs to be of all forms and calmed.

What we're proposing filters traffic through here rather than funneling it.  Filtering traffic allows for positive things like retail to cluster and other synergistic value-added uses, while dispersing bad things like too many cars in one place that delete quality of place.  Mmmmmm, soot, noise, and exhaust.  Hence, why the grid is important.  It provides choice and self-organization.

Several boulevards handling half the traffic is far better for investment and the city of Dallas.  It would only degrade the neighborhoods (already degraded) if designed by your buddies strictly for high speed traffic rather than with other priorities in mind, like economic development, vibrancy, and quality of life...the kind of things "world class cities" make a compromise for.  But it takes a brain to realize the auxiliary effects of underlying systemics.
The TxDOT Bridge Division has authorized about $44 million for work to beef up IH-345. It will easily cost twice that much and perhaps multiples. Expect the money to materialize and the work to start as early as next summer.
The opening of Klyde Warren Park in downtown Dallas has stirred the imagination for bridging the walls to development that freeways represent to communities. Wouldn’t it be nice to have a green covering for North Central Expressway in Richardson, and swingin’ hot spots and civic attractions along side?
Incorrect.  Because the real estate values around the highway in Richardson won't pay for the cost of such construction.  Fortunately, we have the wave of millennials trying to get into cities, the demand of which our current infrastructure is slowing to tiny pockets rather than a coherent, interconnected city.
And surely, you say, there are superior ways to handle traffic demand in the IH-345 corridor and still invite neighborhood development. A big dig there, perhaps?
Start time-lining this thing with history as your guide.
I'll prefer to use the history of urban morphology that I'm a student of rather than the history of TxDOT.  Again, anti-city vs. city.
It was in the mid-1990s that the city and TxDOT cooperated with what they called the Major Transportation Investment Study to try to solve center-city freeway congestion, focused on the Stemmons Corridor. One conclusion was to add capacity to address south-to-north demand by building a Trinity toll road. Now 15 years later, there’s no money for the project and the hurdle of clearance needed for a road between the levees. The only part of the MTIS that’s going forward is the I-30 and I-35 bridge replacement work over the Trinity. Crumbling bridges tend to get noticed and fixed.
Except in the cases where crumbling elevated freeways were determined to be a liability, like New York and Milwaukee, and Seoul.  As for the rest of this passage, are we pretending any of that is a good thing, particularly when predicating it with the infrastructure burden / tax base equation we're basing our entire idea off of?  Good work.  You keep making our case.
Where things stand now, I can’t see where community leaders would support decreasing, rather than increasing, north-south freeway capacity by taking IH-345 out of service — certainly not to chase a real estate play for a few east-west streets between downtown and Deep Ellum. A much larger economy is at stake.
Community leaders eh?  Who would those be?  I don't think your buddies at TxDOT qualify.  This should be determined by a debate at city council.

And larger economies?  You mean like the city of Dallas and its ability to sustain itself, which is the engine of the entire system?  As for regional traffic and interstate commerce, that can do just fine routing around the city.  That freight also doesn't pay its own way, mind.
So let’s say parts of the community get behind the alternative concept of a buried IH-345, based on the idea that it would be aesthetically pleasing and neighborhood friendly. 
Part of the community IS already behind it.  And growing.  Business leaders, neighborhood groups, you name it.
A billion dollars in today’s money might not be too far off the mark, considering that major drainage issues would need to be addressed. But that’s today’s money. Don’t figure a project of that magnitude would get under way inside of 20 years, so you’d want to triple the cost, at least. 
Now we're just making up straw men.  Our plan doesn't cost $1 billion.  Rather, more like $65 million.  Of which, it pays for itself times 65 in property tax revenue alone.  Of which, we can deal with the drainage issues much more easily without having to work around the spaghetti of streets currently in place.  Hey, the revenue could even pay for the drainage issues further east by Baylor.
And imagine making the argument to the Texas Transportation Commission that a below-ground freeway is a critical need. Not. I don’t know where the money comes from for a project like that in a state that’s pushing the big projects into toll financing. I don’t know how you’d toll a subterranean IH-345. Don’t bet on this happening.
It’s probably a much safer bet to put odds on the start date for refurbishing the IH-345 bridge that’s there now. Remember, substandard bridges tend to get fixed. I think Oct. 16, 2014, is a good bet for this work commencing.
Ahh, there it is, stating the inevitability of TxDOT's plan via sources.  Unfortunately, this emperor has no clothes.  But lots of debt.