Prefurbia

Read Part 1 Part 2 Part 4

by Richard Harrison

Prefurbia is a method of designing sustainable neighborhoods. Part one of this series (June 2010) compares the process of Prefurbia with an existing site plan to create a design benchmark.  Part two (Sept 2010) introduces the Prefurbia concepts of pedestrian-oriented design, flow and diffusers for vehicular traffic, architecture in relationship to layout, and architectural shaping. This next installment introduces more methods of Prefurbia.

Design Single-Family and Retail Areas


According to the process for designing a sustainable neighborhood described in part two, the next step using Prefurbia concepts is to lay out the coved single-family area and the retail and office land use along the north boundary of the neighborhood. With coving, you lay out the lot lines last, not first. (Coving is discussed in my previous four-part series in this magazine from late 1997 to early 1998; see the archives on www.profsurv.com). The lot lines are based on a meandering streetscape, and its varied home angles and stretched setback line increase space and density without adding to the street length (Figure 1).

The basis of coving includes home architecture with a floor plan layout that takes advantage of views and architectural shaping, providing a home that fits the lot.  In this case architecural shaping is used to create a home of increased value, but it can also be used to increase density up to 20% without violating existing ordinance minimums. Note how many homes can fit in an area with little constructed street length. (More details are taught in my software Performance Planning System (PPS), described in Part 1.)

In this case we apply coving both along the entrance to the neighborhood and the straight street at the easterly boundary. This creates the feeling of openness and eliminates monotony. 
And because the entrance sets the critical first impression, home flair there creates a welcoming, open feeling and hides the backs of the houses.  We decided not to create an entrance island but instead to use the shapes of the homes for that first impression. 

The temporary (purple) lines signify the minimum front, side, and rear yards. They are at one-degree increments, so when we set the lot lines through these guidlines they will be at even bearings, such as N 36 E instead of N 35 45’56.8” E, emulating clean plats of the old days.  All of the surveyed trees will be preserved in this design, and the main trail ties the single-family region to the remainder of the development.

Prefurbia and Smart Growth promote very different commercial design.  In the original plan, shops are not visible along the perimeter, which means you can’t easily access parking for shopping or service.  Smart Growth encourages walking by hiding the cars and placing the parking areas behind the stores, but Prefurbia makes it easy to walk and drive. 

The “neighborhood marketplace” is a Prefurbia concept where the commercial area is designed to be a function of the residential neighborhood and preserve the auto-centric convenience that makes retail in strip-style commercial centers successful (Figure 2). For example, as you drive past shops, you see a Subway restaurant. You realize you’re hungry, and at the same time your brain registers that it is possible to drive up to the store and get your food within minutes.  That is what creates retail success along main roads: shops appear easy to access, in part because parking is visible.  And although the shops have a main auto-centric front entry, they are designed with a secondary rear entry for pedestrians strolling through the neighborhood.

For the commercial area we chose to have a single, two-way entrance from the north road (a matter of style) because it aligns with a two-way street to the north (reducing maneuvering), and the first island creates a diffuser and an identity for the commercial area.  Some of these elements are more for neighborhood character building than absolutely necessary, but they create an additional element that tends to raise the present and long-term value of homes and non-residential uses. 

Prefurbia also introduces a menu of new commercial design options, which include new zoning that blends residential and office, as well as ascribing to the concept of the cyber village.  This new method, by George Van Hoosen of Springfield, Missouri, aids home-operated businesses with neighborhood community facilities.  This particular plan could easily facilitate a cyber village approach.

Design Townhomes, a Buffer, and Offices


The next step is to design the townhome area and figure out a buffer from the sea of paved area on the southwest corner exception of the site (Figure 3).

With townhomes (as with all architectural design), we need to balance space and yet achieve profitable density. Space is relative—it’s what you feel when you’re on the ground—and what is indicated on the plan may be much different than what you feel.  This concept is called human scale. Townhomes according to Prefurbia are designed to emphasize the front porch and the views from within the homes (architectural elements are explained in part two of this series). Because of the architectural blending of space within the home to create views, the feeling of space will be much greater than if we ignore architecture.

The original plan for the townhomes’ parking area separated cars and did not allow stacking spaces behind the garage doors, which requires a long walk from the parked car to the unit and adds an enormous amount of extra paving.  This increased paving in turn increases environmental impacts and construction costs, making the housing less affordable. To eliminate the possibility of a cluttered look that might detract from the character of the neighborhood, we design the townhomes to hide parked cars and garage doors from the major vehicular and pedestrian systems.

The office-use area buffers the single-family homes from a view of the large parking area (Figure 4). A pond is placed behind the residential area, with views of offices across it.  This provides a sense of space with only a part-time user (office workers) that somewhat preserves a sense of privacy. Note that office parking is across the street from the single-family homes. Ideally, this situation should be avoided because a parking lot near single-family homes can have a negative effect on values. The added green areas in the parking are intended to be landscaped, softening the view.

Trails and Driveways


We chose to design neighborhoods with a minimum walk width of 6’. If your municipality requires a minimum walk width of only 4’, that is not enough for a couple to comfortably walk side by side.  Design the main trail to be wider—in this case 8’ wide—to handle the extra traffic and signify that this is the main walk. This main trail also meanders, which is a signature of our planning firm and a part of Prefurbia.  Meandering itself is not as critical as is the concept of separating the pedestrian and vehicular systems, which meandering allows for.

Want to create a safe neighborhood?  Keep pedestrians and vehicles as far away from each other as possible; it’s as simple as that.

If you think it’s just too much work to design, create easements for, and stakeout a gently meandering, graceful walk that adds character and value to all homes in a neighborhood, then think of Dean Parkway in Minneapolis (Figure 5). This area is almost a century old, designed in the days when there was no CAD or total stations—just raw, hand-calculated geometry with tedious stakeout.  If a surveyor could pull this magnificent system off a century ago, surely all surveyors today will have no problem.

The reason for using straight main trails in the plan described in this article is that the site is relatively flat.  However, building a straight walk and then planting young trees (this is low cost) along each side will eventually form a beautiful canopy within a few decades. This tree-lined walk becomes a visual feature that will be enjoyed for generations and clearly indicates how the neighborhood is interlinked. 

On less-traveled throughways, place a walk on only one side of the street.  Compare a single 6’-wide walk to having two 4’ walks on each side of the street: the 6’-wide walk will encourage use with 25% less total paving width.

All of these small differences create a significant 30%+ reduction in public-street paving, which releases both area and funds to be used to increase value in other ways: a main premise in Prefurbia versus simplistic subdividing of land.

What of the driveways?  They are longer than the conventional plan using coving—doesn’t that increase both volume and costs?  Not necessarily. 

Figure 6 shows a home that is almost 90 years old, built with a driveway serving a rear garage, which is typical of the platting in the 1920s and 30s.  Note how beautiful this Minneapolis driveway is even after almost a century of winters.  More beautiful is the fact that driveways are priced per square foot of paving, and this one has about 25% less total square footage, also lowering the environmental impacts by the same amount.  The visual impact is also less. Again, like in most of Prefurbia, this driveway represents more attention to detail, which has been missing in land development.

Compare that beautiful drive to the one in Figure 7. It is easy to pave the full width of the garage to the street, yet this encourages over-paving.  After all, to create individual geometry on every driveway to show a taper to the street creates more geometry than the effort of creating the lot geometry!

Which home would you want to come home to? The home in Figure 8 began like the one in Figure 7 but with the design changes prescribed in Prefurbia.  Figure 7 shows a driveway approximately 30’ wide and 45’ deep, resulting in 1,350 sq. ft. of paving serving a three-car garage.  Figure 8 shows 650 sq. ft. of paved surfaces serving a two-car garage, but it’s 80’ long!

We achieve the large decrease in paving by sculpting the driveway (Figure 9) according to a map of the tire paths as you enter and exit the garages.  Because the front tires make the car swing out differently on exit than entrance, this requires a bit of detail design work (again fully explained in PPS).  The extra work, however, pays off.

















In the last installment of this series, we discuss the bottom line: how Prefurbia compares to conventional plans numerically.
Rick Harrison, author of Prefurbia and creator of Coving, is president of Rick Harrison Site Design Studio, which offers cutting-edge design solutions that enhance quality of life with the beauty of the natural environment. His technology, Performance Planning System, is marketed through Neighborhood Innovations, LLC.


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