Doing the Math on Sidewalks
Photo by Kelly Lacy from Pexels
Sidewalks are a big topic in my city of Nashville. They are a vital ingredient in a healthy walkable neighborhood. In Nashville, we’re short on sidewalks and trying to figure out how to get more built.
Yet if they’re so important, why have so many Nashville neighborhoods closing in on 100-years-old never built sidewalks? Part of it is math.
Once upon a time, a city had to pay for everything itself. No federal or state grants, and no borrowing. Every amenity had to be paid for up front. The same financial arrangement applied to the maintenance of those amenities. Cash up front, or your sidewalks would be left to crumble. In this environment, cities and towns were conservative. They didn’t build sidewalks until they knew they had enough money to build and maintain them in perpetuity.
Before telephones, the internet, and so few people being educated in mathematics and finance, how did they know if they had enough money? They observed and copied.
Every city is an ongoing complex experiment. When cities grow, they copy templates from other cities and other sections of themselves. As far as sidewalks go, throughout history, people observed cities and copied the patterns they saw. The math behind the ability to maintain sidewalks didn’t have to be understood in numbers. It was observable in building height and density. For example, someone who visited the city of Boston in 1840 might have observed that there were cobblestone sidewalks next to rows of densely built three-story houses, but only a dirt path in less dense parts of town with one-story structures. This was a free visual economics lesson. The visual cues were telling everyone, “You need at least this much wealth to draw from to fund the building and maintenance of cobblestone sidewalks.” If a town went against the free economics lesson, it likely found itself very quickly out of money. And thus the lesson was reinforced and successful patterns copied over and over.
With the way much of our infrastructure is financed today, there’s a tendency to think of infrastructure funding in the abstract. The two dominant views are: “I pay taxes so I deserve sidewalks” or “Someone else will pay for all or part of the sidewalks.” The problem with the first view is that there’s no context; you really have no idea if your personal taxes are enough to build and maintain sidewalks. The problem with the second is that relying on others to pay for you is unrealistic and unreliable.
Let’s use some made-up numbers to create a scenario. You have street frontage of 100 feet and want sidewalks in your neighborhood. Your home is worth $200,000 and, for simplicity, we will say taxes are 1%, or $2,000 per year. Also for the sake of argument let’s say that 95% of your tax money is spoken for by other items like schools, police, sewers, etc. Out of your $2,000 per year, $100 is available to put towards your wish of 100 feet of sidewalk frontage.
At this point, you might be saying something like, “Sidewalks are a common good, so everyone should pitch in.” But who are these mythical generous people pitching in for your sidewalks? And if others are pitching in for yours, then wouldn’t other people expect you to pitch in for theirs? For this reason it’s easiest to assume everyone pays for the sidewalks in front of their own property, and charges $0 for others to use them. As for the “federal grant” or other source of funding, this will work to get the sidewalk built—but there is no guarantee that enough money will be available for future maintenance.
Back to the math. You learn that 100 feet of sidewalk costs $4,000 up front and lasts 20 years. Twenty years of the $100 you have allocated towards sidewalks adds up to $2,000. You cannot afford a sidewalk. But what if you split the property and build a second home on the same lot? Now you have twice the tax power to go towards sidewalks. If the house is of identical value and taxes, you will have achieved the needed $4,000 in taxes to build and maintain your 100 foot stretch of sidewalk for its 20 year life-span. This simple example explains why sidewalks are seen more often in areas with higher density. Higher density means there is more total wealth to draw from to fund and maintain the sidewalk.
One reason Nashville lacks sidewalks is that its homes are built too far apart to make it financially feasible.
But this isn’t the only reason. Neighborhoods like Lockeland Springs have street frontages of 50 feet each and have sidewalks, whereas many streets further into East Nashville have similar lot sizes—and thus similar financial equations—yet they still lack sidewalks. This might be explained by the era in which the neighborhoods were built. Neighborhoods that were finished before 1920 would have valued sidewalks more because the automobile was not yet dominant. Whereas neighborhoods that developed through the 40s, 50s and 60s saw resources drawn away from walking amenities towards automobile oriented amenities like wider roads.
I hope you have enjoyed this edition of Sidewalk Math!
About the Author
DJ Sullivan is a native of Rochester, New York. He currently lives in Nashville, Tennessee. Reading Walkable City by Jeff Speck in 2013 kindled his interest in urban planning. He is an accountant and enjoys writing and traveling. This article originally appeared on his blog, East Nashville Urban Design. You can connect with DJ on Twitter at @UrbanEastNash.