Smart Growth and New Urbanism have increasingly merged into a loosely aligned set of ideas. The benefits of this high-density housing viewpoint are fast becoming a ‘given’ to planners and city governments, but studies that promote the advantages often omit the obvious disadvantages. Here are some downsides that show a much different story:
Smart Growth or Dumb Idea?
One goal of Smart Growth is to move our society away from dependence on cars, and many Smart Growth plans intentionally make it difficult to drive through the neighborhood, making walking more inviting. Smart Growth planners advocate short blocks in a grid pattern to distribute traffic (vehicular and pedestrian) evenly within a development. These short blocks produce a multitude of 4-way intersections, and add a multitude of those trendy “turnabouts,” to make a bland site plan look more interesting.
But all of this together destroys “flow”. On the other hand, in a grid planned neighborhood you might drive a straight line with an occasional turn, giving the impression of a much shorter drive than a curved subdivision. But with short blocks, a driver must stop completely, pause, then when safe accelerate through the intersection onto the next intersection, then repeat… multiple times. This scenario uses a tremendous amount of energy; the car eats gas.
To understand this point clearly, go out and try to push a modern car. All the safety and convenience features, even in the most basic car sold today, add weight. Even a Toyota Prius is just under 3,000 lbs. While a given model may get great mileage the bulk of energy consumed is in getting the thing moving from a full stop. Should a vehicle maintain a constant flow (at any speed), the energy usage plummets, compared to stop-and-go traffic patterns that intentionally force conflicts.
To make matters worse, the majority of vehicular vs. pedestrian accidents occur at intersections. Smart Growth designs have many more intersections than conventional suburban plans . Even more dangerous, Smart Growth walkways are placed close to the where the cars turns. Check out Traffic by Vanderbilt
One may argue that cars will become more efficient. So what? This stop and go scenario also consumes time.
Rooting Out Tree Issues
Nobody can argue against the character of a tree-lined street… no one, that is, except the city Public Works department that must maintain structures being destroyed by trees growing in close confines to concrete walks and curbs. Smart Growth/New Urbanist compact front yard spaces are typically 10 feet or less. This simply cannot provide for enough room for tree growth when there is a 4’ wide walk typically a few feet away from the curb, the area where street trees grow. Without trees to define the street, these solutions have very little organic life to offset the vast volume of paving in front of each porch.
Now and in the near future there will be a new era of solar heat and power, most of which will be mounted on the roofs of homes. Guess what blocks the sun's energy? Yep – street trees! High density means that the proximity of trees to roofs will deter the sun’s energy from reaching those solar panels.
Get Real About Presentations, Porches and People
Typically, when a high-density development is proposed, the renderings show large green common areas bounded by homes with grand porches. The presentations usually show only a few cars parked along the street, and plenty of residents enjoying the spaces lined by mature trees that have had about 20 years of growth. This misrepresentation helps to win over councils, planning commissions and concerned neighbors. What is not shown in the presentations for approvals are claustrophobic, intense areas, such as the typical street most residents will live on, or perhaps the views down the alleys.
There may be some neighborhoods that are built as represented, but architectural and land planning consultants are likely to stretch the truth more than a wee bit to gain approvals. Where can we see the original presentation images compared to what actually gets built?
Those inviting large porches where neighbors sit and gossip in the presentation: Do they ultimately end up as stoops hardly large enough to fit a standing person? Those large mature trees: Are they actually just seedlings? Does the real streetscape have people walking on the typically narrow 4 foot wide walkways? How many people are walking along the roadway instead? Are the streets lined with just a few cars, as the renderings show, or are they packed with unsightly vehicles, while the nice cars are likely stored in the rear garage?
The Evolution of Pavement
Suburbs have changed during the last few decades. For example, in Minnesota thirty years ago an average suburban lot would have been 15,000 square feet and 90 to 100 feet wide. Today, 8,000 square feet and 70 feet wide would be more typical. In a conventional suburban plan, there weren’t any alleys, and the front loaded driveways were appropriately tapered. There were few side streets. The lots might have been 20% larger than in a Smart Growth high density plan, but the street layout might have had about 30% less linear feet of street compared to a Smart Growth grid layout. In the south, where the typical suburban lot is about the same size as that high density lot, the numbers favor the conventional layout even more; the total paved surface area could be 50% or more lower. So, the Smart Growth/New Urban plans place a greater burden on the tax payers to municipally maintain (more) paved surfaces.
A Final Consolation...
In reality, fire and police departments, as well as traffic engineers, review suburban development plans. And often the original high-density narrow street proposal doesn’t make it all the way to approvals. With or without the popularity of Smart Growth and New Urbanism, a much wider paved section or a compromised width is often the ultimate result.
Rick Harrison is President of Rick Harrison Site Design Studio and author of Prefurbia: Reinventing The Suburbs From Disdainable To Sustainable. His websites are rhsdplanning and prefurbia.com.
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Inefficient stop and go?
Even a Toyota Prius is just under 3,000 lbs. While a given model may get great mileage the bulk of energy consumed is in getting the thing moving from a full stop.
It's odd that he brings up the Prius, since I thought it was well-known that the Prius generates an electric charge through braking, and gets slightly better mileage in the city than on the highway. All those stops are just powering it up.
It doesn't matter though, since as Steve Mouzon points out, this is not really an accurate description of the typical pre-war (not just New Urbanist) gridded neighborhood. All the ones I am aware of (in Nashville anyways) have a couple wider, uninterrupted (except for one stoplight) east/west and north/south streets for through traffic. Proper location of these through streets means that, even if you live in the neighborhood, you need only go through one or two stop signs to get home.
Seriously Flawed Article
Wow, there are just so many errors and half-truths here... where to start?
As for "destroying flow," New Urbanist neighborhoods aren't usually one big fabric of 4-way stops. Vicksburg, Mississippi is... and it's really aggravating driving there. What normally happens is that the smaller streets have the stop signs and the bigger streets at the edges of the neighborhoods do not, for the most part. So if you're on the edges, you can drive quite a distance without stopping. We want people to slow down so the kids are safer, but you don't have to stop people at every corner.
As for the majority of pedestrian/auto accidents occurring at intersections, of course that's right... many cities have jaywalking laws, and you can get arrested or ticketed for crossing the street anywhere else. So that's where the accidents occur in anybody's development, New Urbanist or not. The key is slowing down the traffic so that you don't get killed. If you're a pedestrian and get hit by someone driving 25 MPH, you might have a broken bone or two, but if you're a pedestrian and get hit by someone driving just 10 MPH faster (35 MPH,) you're almost guaranteed to ket killed. Shorter blocks have been proven again and again to slow traffic. Long blocks create speedways. New Urbanism keeps you safer.
As for street trees, why does this article bring front yards into the discussion? Street trees by definition grow in the street right-of-way, usually between the sidewalk and the curb. The size of the front yard has nothing whatsoever to do with the issues the article is complaining about. As for the Public Works Department carping about having to maintain sidewalks near street trees... what do you propose? Cutting all the trees down and having a barren, ugly, hot street instead just so the city doesn't have to occasionally do a little maintenance? If that's what you want, then there are plenty of really ugly suburban streets you can choose to live on. Me, I love my tree-lined street that is not only beautiful, but probably 15 degrees cooler in the summer than if it were barren. I know. I walk to work, and part of the walk is on the tree-lined street, and part is on a barren street. I experience the huge temperature difference and beauty/ugliness difference every day.
And what's this about 4' sidewalks? I don't know any New Urbanist planner that uses those. Most of us use 5' or even 6' sidewalks because they're more comfortable to walk side-by-side. We're trying to encourage people to walk.
As for solar access, street trees aren't directly over very much of the roof of the house, so they only shade significant parts of the house very early or late in the day, when the efficiency of any solar collectors would be steeply reduced. And let's get real about solar collectors; all the PV's you need for electricity and all the hot water collectors you need still only take up a minority of the roof space of a 2-story home. So just exercise your design abilities and don't put them near the street trees. Do you really want solar collectors on the very front of your house anyway?
As for the presentation, this article carps about showing trees that have had 20 years to grow. So do you think the neighborhood is going to get bulldozed before 20 years have passed? Or maybe you're proposing to just cut the trees? If not, then ... news flash ... trees grow! And they really will look like that! Just not on Day 1.
As for the alleys, this complaint makes no sense whatsoever. Guess what happens with all that messy stuff on the alley (garbage cans, utility boxes, etc.) if you DON'T build an alley and build a normal suburban street instead? All that stuff is on the FRONT of the house... on the street. Alleys allow the street to be beautiful by moving all the messy stuff around back.
As for the porches, no New Urbanist I'm aware of allows porches less than 8' deep. And many are deeper. The author is getting New Urbanist porches confused with the completely useless 3'-4' deep porches found on typical suburban houses. Those are nothing more than expensive decoration. New Urbanist porches, because they are deeper, can actually function as outdoor rooms.
As for the lot size/infrastructure issues, this is just plain wrong. Let's do the math. A typical suburban street in most cities is 36-40' wide. Let's use 40' for easier math. Because two houses across the street from each other share 40' of pavement, each is responsible for 20'. So for the 100' wide lot the article mentions, each lot requires 20 x 100 = 2,000 square feet of street pavement. Meanwhile, a 50' lot is slightly wider than average in most New Urbanist developments. And we're always working to make the streets narrower to slow the cars so the kids are safer. So if you have two 9' travel lanes and a 7' parking lane on one side, that's a total of 25' of street width which two lots share, or 12.5' x 50' = 625 square feet of pavement. Now, assuming the alley is paved, add half of the 12' wide alley (since you share the alley with the house behind you) for 50' x 6' = 300 square feet of alley paving, or a grand total of 925 square feet of paving... less than HALF the paving per lot of the suburban model. How about the rest of the infrastructure? A complete no brainer, since infrastructure per lot is equal to the lot frontage. So the New Urbanist lots averaging 50' wide require HALF the water lines, sewer lines, cable, electrical conduit, etc., of the 100' lots.
This is an open invitation for the author of this article to contact us... whoever has been advising him has been giving him some excruciatingly bad advice, and I'd like for him to get the real picture.
Steve Mouzon
http://www.newurbanguild.com
http://www.originalgreen.org
http://www.mouzon.com
Steve Mouzon: As for the
Steve Mouzon: As for the presentation, this article carps about showing trees that have had 20 years to grow. So do you think the neighborhood is going to get bulldozed before 20 years have passed? Or maybe you're proposing to just cut the trees? If not, then ... news flash ... trees grow! And they really will look like that! Just not on Day 1.
Thanks for bringing that up, I noticed that error too. You always show trees at about 2/3 maturity in plans and perspectives!
I wonder if this "prefurbia" guy has actually designed something in real life. Do you have any drawings of built works to show us? Any case study examples of "prefurbia"?
But with short blocks, a
But with short blocks, a driver must stop completely, pause, then when safe accelerate through the intersection onto the next intersection, then repeat… multiple times. This scenario uses a tremendous amount of energy; the car eats gas.
Not all four way stops even have stop signs, and many four way intersections allow for one flow of traffic to move through without stopping (and the other side to stops).
If energy is the issue, then the random "flowing" and inefficient streets that go nowhere in particular of most suburban developments should be criticized.
To make matters worse, the majority of vehicular vs. pedestrian accidents occur at intersections.
If safety is the issue, you should address backing up - which is very dangerous and every typical suburban house has a driveway leading to a garage.
221 people were killed in 2007 from backing up of a car, and 14,000 injured. 44% of all fatal nontraffic injuries of children under 15 were from cars backing up.
http://www.nytimes.com/2009/04/12/automobiles/12VIEW.html?_r=1&ref=autom...
The culprit isn't just intersections (you can't avoid those), but backing up.
I am not familiar with cars jumping the curb on turns in properly designed streets. How often do you hear of a car running a curb even in a dense urban environment? However, I have seen cars in a parking lots accidentally push the gas instead of the brake and run right through storefronts.
This simply cannot provide for enough room for tree growth when there is a 4’ wide walk typically a few feet away from the curb, the area where street trees grow. Without trees to define the street, these solutions have very little organic life to offset the vast volume of paving in front of each porch.
Now and in the near future there will be a new era of solar heat and power, most of which will be mounted on the roofs of homes. Guess what blocks the sun's energy? Yep – street trees! High density means that the proximity of trees to roofs will deter the sun’s energy from reaching those solar panels.
10' is plenty room for almost any street tree species for most municipalities (in designated street tree strips).
Here is a streetscape of Savannah, GA. It shows a live oak lined street with fairly wide street tree pits and absolute building frontage to the street - no front yards. You're making it sound complicated, which it is not:
Savannah, GA Streetscape
Regarding solar access, tree coverage over your home during summer months reduces energy costs drastically as opposed to being exposed. You'd essential be generating electricity to cool your home, which is perplexing (I've actually seen solar panels on a home in a NU neighborhood).
A street section of a 7 foot tree strip, 4 foot sidewalk, and 10 foot setback - with a nice mature tree of 30 feet wide is not going to entirely kill your solar access. Coupled with the fact that many buildings rise higher than the tree tops.
Density is not the issue as large buildings in dense settings are going to be great at capturing the sun in the future.
The lots might have been 20% larger than in a Smart Growth high density plan, but the street layout might have had about 30% less linear feet of street compared to a Smart Growth grid layout
I'd also disagree with your assessment of more pavement in NU communities (although I do feel that alleys shouldn't be paved). There are more total dwelling units within a given "slice" of street, which maximizes the infrastructure.
unpaved alleys - What?!
"although I do feel that alleys shouldn't be paved"
What?!
Dirt alleys! No way. My alley is paved with asphalt and I don't like it one bit. I want concrete like the rest of my neighborhood. Concrete is easy to keep clean.
Dave Barnes
+1.303.744.9024
http://www.MarketingTactics.com
I think gravel alleys work
I think gravel alleys work well. Nobody said anything about bare soil alleys!
I'd take porous asphalt or interlocking pavers (like Chicago "green alleys" have) any day over pure concrete.
Have you tried to wash gravel?
Concrete alleys can be hosed down and made very clean and sparkling. The others can not. I want my alley to be as clean as my concrete floor garage.
Gravel? Right! Not. I can just image what the garbage trucks would do to a gravel alley during their weekly visit.
Grass pavers? And who is going to water them? God (if you believe in such things) provides 40+ inches of water each year in Chicago. Only 15 inches in a "normal" year in Denver. Last year it was 10 inches. Not enough for grass in an alley.
Dave Barnes
+1.303.744.9024
http://www.MarketingTactics.com
I have never heard of a
I have never heard of a grass alley, and I was referring to concrete, interlocking pavers.