More tall buildings like this one are coming, but that doesn't make Reston a new Manhattan. Image by Adam Theos licensed under Creative Commons.

Reston is set to grow a lot over the next couple of decades as Metro's Silver Line is completed, transforming parts of the area from quiet, isolated office parks to denser office and apartment buildings. However, it's important to remember that density is just one measure of what a community feels like, and there are many ways to arrive at the same numbers of people per square mile.

Reston's Master Plan was revised after an extensive six-year process, and explicitly says where it will likely grow and by how much. Now that Fairfax County is enacting some of the technical mechanisms to make those agreed-upon changes happen, there's been a lot of pushback.

One group opposing these changes is Reston 20/20, which wants to stop or delay those changes because it believes Reston's population would grow too much and make the area too dense. One of the group's leaders, Terry Maynard, recently wrote an op-ed for the local blog RestonNow claiming that the Master Plan would make parts of Reston denser than the borough of Manhattan in New York City. He writes:

According to Wikipedia, Manhattan has a density of 26,403 pers/Square Mile. That makes the planned population of Reston’s [Transit Station Areas between 35,200 and 48,000] at least one-third denser than and potentially nearly twice as dense as Manhattan is today.

That sounds pretty dense! There are just a few problems with this calculation and what it means. Let's deal with the biggest one first.

There's a big math error

First, Manhattan doesn't have density of 26,403 people per square mile. Based on 2017 census estimates, the population density of Manhattan is closer to 75,000 people per square mile. But if you measure by kilometers rather than miles you get that figure of 26,403 people.

That's a major miscalculation. If you confuse kilometers for miles while driving in Canada, you're going to get yourself a pretty big ticket.

This is a table you'll see if you visit the wikipedia page for Manhattan.  Image licensed under Creative Commons.

Okay, so turns out Reston isn't going to be as dense as Manhattan. If folks only based their opposition on that, then this clarification ought to save everyone a lot of time and energy. Still, some might balk at future projections because 48,000 people per square mile still sounds (and is) pretty dense.

In fact, it is denser than Brooklyn — but raw density numbers don't tell us everything either.

Comparing oranges to the Big Apple

Manhattan is just one specific part of New York City. It's the part that outsiders are usually the most familiar with, and it definitely has a high concentration of tall buildings and skyscrapers. But the whole island is about 10 times the land area of the Reston Transit Station Areas, or TSAs, where much of the new density will go.

Reston's TSAs are all located in a fairly narrow band of land that runs close to the Dulles Toll Road and Silver Line. Already this comparison to Manhattan is a problem because we're juxtaposing one or two neighborhoods against an entire borough or county. It's like looking at a picture of rural Clifton and assuming all of Fairfax County looks like that.

A map of the Reston Transit Station Area.  Image by Fairfax County.

Maynard mentions that on a per-acre basis, the Transit Station Area could have a density of up to 75 people per acre. Most of Manhattan is a lot more dense than that —108.5 people per acre in 2010, to be exact.

However, parts of Reston might be as dense as Brooklyn or the Bronx. Still pretty dense! But again, that's borough-wide, and both of those boroughs are far larger than Reston or Manhattan and density isn't uniform. Even in bustling New York City, there's plenty of room for smaller buildings and sprawling parks.

Population density by Census Tract in New York City. Reston's TSAs are as dense as the areas that are light orange here, which you don't see a lot of in Manhattan but do get in outer boroughs.  Image by New York City.

Density is a tool, not an end-state

The density Maynard is writing about will only occur in the area inside the Transit Station Areas, which make up about 15% of Reston. Most of the TSAs today are either already dense apartment buildings, or are older office buildings that may include new homes and shops in future redevelopment. It's all very close to where the Silver Line is running and where Reston sees its most frequent bus service.

If you have to put a bunch of new stuff somewhere, then concentrated right by transit is a pretty good way to do it.

This does mean that the amount of density measured across the entirety of Reston will also grow, but the built environment won't change much outside of the TSAs. Numbers are one thing, but what density looks like is another — anywhere that's a leafy suburb today is pretty much going to stay that way. That's a good thing for people who want to keep a supply of detached homes close to Reston's core, and only bad for those who just don't like tall buildings.

If tall buildings are the problem, we could upzone Reston overall to allow more townhomes and smaller apartment buildings and arrive at the same density numbers. But after six years of working out the Master Plan, it's pretty clear that residents wanted to keep most of Reston looking the same, and put most of the changes closer to metro.

This is not the future of Reston.  Image by Andreas Komodromos licensed under Creative Commons.

Some of the effects of increased density inside the Transit Station Areas will be felt in Reston at large, but then again, so will changes outside of Reston. Congestion won't magically improve if all the growth slated for Reston happens somewhere else in Fairfax.

Reston's reputation as a jobs hub means plenty of people will still drive in from places that don't have brand new metro lines running through the middle. That means more traffic without the benefits density can bring, like new places to live, shop, and work.

That's the issue with assuming that by stopping people from moving to Reston, you can prevent other bad things, like increased congestion or crowded schools. People don't plan their lives around the administrative borders we draw around communities. That is why I say that density is a tool, and not an end-state.

This is also what Brooklyn looks like. Image by the author.

Fairfax County planners didn't come up with their estimates because they're fans of tall buildings or have some vision of cramming people into apartment blocks. It's because they have a responsibility to help manage the growth of a very large county in a way that doesn't compound earlier planning mistakes — mistakes that assumed we could drive anywhere we wanted without dealing with congestion.

Plus, these are the maximum figures that assume every parcel is built out to be as dense as allowed. We could arrive at a number well below the maximum.

The idea of thousands of people per square mile can certainly sound intimidating, especially if the only context is the largest city in the country. However, plenty of people in the Washington region live in neighborhoods similar to what is planned for the TSAs in Reston. Others live in less-dense places close to dense neighborhoods, which are often highly sought after because they offer a compromise between private space and public amenities.

Density close to transit, careful planning, and comprimise are all elements of a healthy community, and that's exactly what's happening in Reston. Don't let a fear of big numbers or bad comparisons to other cities tell you otherwise.