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 for an understanding of the psychology of driving.
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.