iA


Choose the Grid? Absolutely.

by Paul Knight. Average Reading Time: about 10 minutes.

Fanis Grammenos, a principal of Urban Pattern Associates, recently published an article at Planetizen.com titled “Choosing a Grid, or Not.” The article addresses the question “What should be the preferred layout for a new neighborhood?” while focusing specifically on the grid plan. I encourage you to read the article, but to summarize here are three points that were made which I would like to focus on:

  1. Many grids with small blocks are inefficient due to their low developable land to total area ratios.
  2. Towns and cities throughout America and the world have either abandoned the grid or avoided the grid because they found it undesirable.
  3. Grid plans are outdated because many of them were established at a time when horse and buggies and unsustainable development patterns proliferated.

While I commend the thorough analysis that was done for the article and welcome the discourse on the grid plan, I must disagree with some of the conclusions that were drawn and the negative assessments that were presented. That being said, as a grid-enthusiast I feel compelled to defend the orthogonal grid on each of the above points.

1. Land Use Efficiency

With data on 20 different American grid plans, the article presents a comparative analysis looking specifically at “land use efficiency” (which I will shorten to “LUE”). LUE is defined as a simple ratio of sellable (or useable) land divided by total area including rights-of-way. Or, put another way:

LUE = Private Land / (Private Land + ROW’s)

The idea behind this ratio makes sense: the more land available to be utilized per unit area the better. In other words, a city is more efficient when a maximum of available land is obtained with minimum access. In this view, a city that is comprised of an inordinate amount of land devoted to rights-of-way is considered inefficient since much of the city’s land is used simply to access the rest of its land. Portland, OR is the main example highlighted in the article as an inefficient city because so much of the city’s land is taken up by its rights-of-way (41%) leaving only 59% of it to be available for actual development.

While this analysis has some validity, the problem with LUE is that it makes suburban superblocks look highly efficient when we know this not to be the case. To get a more efficient reading using the LUE ratio you would have to minimize the number of rights-of-way. Superblocks do just this. They maximize their interiors and minimize their exteriors.

The rise and fall of cities is not based on the amount of land they have available alone. I propose to supplement or replace the LUE ratio with the concept of street frontage and access. What makes a grid plan so efficient is not the gross land devoted to one thing or another but the subdivision of the land itself into organizable and useable units. As an analogy, a pile of books on the floor is almost useless to the researcher who must be able to efficiently find and access information. The library fixes that problem by providing a framework of shelves within which books can be placed. The aisles between those shelves provide the access. Similarly, the fine-grained and orthogonal framework of rights-of-way in grid plans gives both organization and access to towns and cities.

Street frontage is critical in creating vibrant, varied, and sustainable places. More streets means more route options, more corner lots, more store fronts, more front yards, more access. It is not just the quantity of space that is important; the accessibility of space is equally as important. While a city composed of nothing but rights-of-way is useless so too is a city composed of nothing but private property.

The article’s analysis shows that Portland only has 59% of its land available for development while Salt Lake City has 72%. This makes Salt Lake City appear to be much more efficient than Portland. However, if you calculate the amount of street frontage within an area you get an entirely different story. Within a 1.5 square mile area, Salt Lake City has 180,480 lineal feet of street frontage. The same area in Portland yields 474,000 lineal feet–that’s 163% more than Salt Lake (see notes 1 and 2 below). Comparing these numbers, Portland’s urban permeability is the clear winner. While Portland has less developable land than Salt Lake, it makes up for this with its superior distribution and access. If efficiency is the goal, one should promote quality of space over quantity of space.

Note #1: Even if you take into account the fact that Portland’s small 200 foot blocks could only have at most 2 sides of front-facing lots (not 4) because the depth restricts it, Portland would still have 237,000 lineal feet of front-facing lots or 31% more than Salt Lake.
Note #2: This is not an argument necessarily supporting Portland’s small 200 foot dimension which over time has proven to be difficult to work with. The point being made here is that LUE and street frontage are two different measures of efficiency with two different interpretations.

2. The Grid: Avoided and Abandoned

The article presents a number of quotes, references, and studies that all cast the grid in a poor light. For example:

If replication is any indication of merit, the historical record of towns that abandoned the original square mile gridded plan as they grow in size does not bode well for the simple grid.

While it is true that towns and cities have essentially abandoned the grid, this is not the grid’s fault. Numerous other factors are responsible; chief among these are the unintended consequences following the Enabling Acts of the 1920’s. The concept of the master street plan as specified in the Standard City Planning Enabling Act was intended to allow municipalities to establish streets ahead of time just as they did in Manhattan in 1811. Unfortunately this was not carried forward. Instead, the City Planning Act was overtaken by the Standard State Zoning Enabling Act and essentially forgotten. Zoning was adopted first because people were literally dying from their proximity to “incompatible uses” (houses next to coal-burning factories, etc). Zoning saved lives, but as we know today the States put the cart before the horse by addressing zoning first without the master street plan. Zoning provides no physical framework for a city in the way that a master street plan does, but as zoning gained in popularity, street planning lost its appeal. As states and cities lost their desire to plan and connect streets, the grid was given no where else to go.

Secondly, regulations began to attack the basic components of the grid including its small blocks, connected network, incremental development, etc. For example, half streets and dead-end streets are necessary for developers to share the burden of construction and create opportunities for future street connections. Early on, regulations forbade half streets and the connection of dead end streets (as they did in the 4th chapter of Atlanta’s 1954 ordinance). This made the incremental development of grids difficult or impossible to execute. A developer could no longer leave a street open for future connections to be made; rather, they were forced to complete all of their streets fully within their property lines. Thus, it is not surprising that the cul-de-sac proliferated under such conditions. Add on top of this large minimum block size requirements and again the grid was being regulated out of existence.

Finally, the grid was simply unable to sustain the barrage of academic attacks from the likes of Ebenezer Howard, Le Corbusier, et al, who all pushed their utopian visions of Garden Cities and free flowing highways. Even John Reps, with his masterful work and clear understanding in his book The Making of Urban America, had little if any appreciation for the grid beyond viewing it as an historical artifact.

With all of this, it is no wonder that the grid has waned.

Finally, the article presents a quote by Christopher Alexander, et al, saying that:

“For thousands of years, historical cities avoided straight lines.”

While it is certainly true that many historical cities either intentionally or unintentionally avoided the grid, this neither supports nor denies the counter claim that many cities did in fact embrace the grid. Hundreds if not thousands of Roman grid towns employed the 90-degree angle of the Cardo and Decumanus. Hundreds if not thousands of towns were framed by the Laws of the Indies. Thousands of years ago, the urbanized world was first introduced to the grid plan. Here at home, every one of the United States have utilized the grid plan. While the grid has been avoided in some places it has been celebrated in others for literally thousands of years.

3. The Grid is Outdated?

The article concludes by calling the grid “outdated” and proposing three steps for updating the grid:

Breaking the convenient, but outdated, uniformity of…American grids would be a first step… A second step would be to include block sizes that can accommodate building types and sizes unknown in the 1800s… A third step would be to adapt its streets for the now universal motorized mobility of cars, buses, trucks, trams and motorcycles, that is radically different from when oxen, equine and legs shared the transport of goods and people.

Before I respond, first take a look at the images below:

A dump truck in Savannah, Georgia.

Subway entrances, cell phones, semi-trucks, moving vans, pharmacies, high rises, baby strollers, and telephone booths in New York. There may be a Segway in there, too.

Multi-story parking deck in Chicago with Trump Tower in the background.

The grids of Savannah, New York, and Chicago were drawn hundreds of years ago. Yet you will notice that modern life has found its way within all of them. In each picture you see building types that were unknown in the 1800s and modern means of mobility that have advanced far beyond the horse. Still, the block dimensions that were handed to us have readily accommodated all of this.

When James Oglethorpe designed Savannah did he seek to accommodate dump trucks, movie theaters, and high rises? When the New York commissioners designed the Manhattan grid in 1811 did they knowingly prepare for subways, grease traps, and the Empire State Building? These early city planners were not fortune tellers. The plans they developed were not imbued with some divine power of foresight. Rather, the dimensions that were chosen have simply perpetuated themselves into our built environment over decades and centuries allowing these city blocks to accommodate one future after the next.

The fact that horses were driven through the streets of Chicago in no way prevented the accommodation of the future automobile; if anything they assisted it. After all, horse drawn carriages and modern minivans are roughly the same size. Rather than make predictions, these city planners simply left us with a dimensional framework that continues to work for us.

The repetitive, uniform, monotonous blocks of Manhattan have accommodated everything from farms to skyscrapers—literally. For example, the block at Madison Ave. / 71st St. used to be Lexington Farm–a rural farm surrounded on all sides by right-angled streets and sidewalks. Today, that exact same block has been dramatically repurposed to include skyscrapers. Now that is an efficient use of land.

With this in mind, it is critical that today’s city planning professionals trust precedent. The grid simply works. There are literally hundreds if not thousands of precedents of the grid in every corner of the United States and every corner of the world that can easily support this claim. The grid is not outdated; far from it. The grid is timeless.

Conclusion

Grammenos raised some interesting and important questions in his article, but I disagree with some of the negative assessments of the orthogonal grid plan. I would be the first to concede the ineffectiveness of the grid if it consistently produced failing, boring, and undesirable towns and cities, but the precedent that the grid has set does not lead me to throw in the towel. Chicago, New Orleans, San Francisco, Seattle, New York, Oak Park, Great Falls, Owatonna–each one of these lively towns and cities share the exact same geometry. The grid is not a precedent in need of help; it is one which has already proven itself for centuries. In many cases, copying the grid uncritically would be OK.

To summarize my stance on the grid plan I wrote this poem in a previous blog post. In closing, I reproduce it here for your convenience and reading pleasure:

We live in rectangular places, we park in rectangular spaces / The orthogonal grid—it thrives, due to the way that we live our lives.

4 comments on ‘Choose the Grid? Absolutely.’

  1. Great response Paul. My home state, Oklahoma, provides an interesting example of the flexibility and timelessness of the grid. Because of the Land Run of 1889, when land was parceled and given to pioneers in quarter sections, a grid exists in Oklahoma which extends for hundreds of miles in each direction. Almost the entire state is a continuous grid. It poses some challenges, but works well for connectivity in both urban and rural areas. Long live the grid.

  2. My observations of cities haven’t convinced me that the grid is always the best form. If you have lots of mixed use, and high density, a grid makes destinations easier to find, and it’s porosity makes the perfect pressure relief valve for those peak traffic times.

    Paris, Rome, and Sydney don’t have grids.
    They are interesting and walkable. Historically, they were a bit hard to navigate for the newcomer. GPS has fixed that, even for pedestrians. Their streets grew organically around the topography and without much planning. A grid for them would increase utility at the expense of charm.

    There’s an old neighborhood in Denver called Bonnie Brae that was planned in about 1910 and built out over the next three decades. It has curvilinear streets, a diagonal collector road, but no cul-de-sacs. It was designed this way because the private developer thought it would be more interesting, charming, and exclusive than the surrounding grid neighborhoods. He was right, even though many backyards were reduced to skimpy triangles.

    In the 50’s & 60’s this charm was noticed by the suburban developers, and they replicated the style in their new automoblie suburbs, added gates, cul-de-sacs, and high speed perimeter thoroughfares. The charm and walkabilty were utterly destroyed by the car-centric design.

    So the grid makes city planning and development easier and more predictable, but folks will eventually get a little bored with it, and it doesn’t make a better city by itself.

Leave a Reply