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If cities are molecules, streets are atoms. They are the most fundamental element in city-building. And I bet you thought they were merely conduits for cars. Everything stems from the guiding principle that cities exist to bring people together. Cities are places of exchange - economic, social, cultural - and opportunity, where residents share in a common good. Streets have two parts, the public realm and the private realm. Part 1 of this series details important design elements of the public realm. Part 2 will do the same for the private realm.

The first article I wrote was meant to be a primer on cities - what they are, what they're for, how they were mutated by the automobile, and why they are on their way back. If you haven't read it, now would be a good time to do so in order for us to be on the same page. It was meant to be a very high-level introduction, painted with a very broad brush. This two-part series will be the opposite. Instead of looking at cities from 30,000 ft in the air, we are going to go to street-level in order to better understand what makes cities either great people places or hostile people places. We are doing this because streets are the building blocks of cities.

The Public Realm

There are many examples of public space in cities. None is more important or more influential on livability than its streets. Streets represent the single largest public asset in a city. Urbanists often think of streets as the "public living room". They are places for people to come together and commune outside the privacy of their homes. Do you remember the scene in the movie "It Takes Two"? Remember the scene when the kids are playing pick-up baseball in the streets? That's what "living room" means. The importance of streets derives from the simple fact that they take up a lot of space - New York's streets are roughly 30% of land area, for example. With so much space devoted to streets, it becomes critical for a city to get street design right. 

Cars vs. Pedestrians

Incidentally, streets are the first place to look in discerning whether a city prioritizes pedestrians or cars. One quick glance is all it takes. If your city prioritizes pedestrians, its streets have the following characteristics:

  • They exist within a traditional gridded network, forming a logical pattern of streets and blocks.
  • Block lengths are 300 ft long or less.
  • Narrow streets, with lanes 10 ft wide or less, and no more than three lanes total (one travel lane in each direction plus a middle turn lane).
  • No crosswalk buttons

If a city follows these steps, they'll get streets that look like this:

You'll note Figure 1 also shows bike lanes and parking lanes in addition to the two travel lanes and middle turn lane. In general, biking lanes and on-street parking are good things. Bike lanes add another mode of travel and parked cars provide a buffer for walkers. But it is important to always orient one's thinking around the importance of street narrowness above all else. This is the single best tool a city has to make its streets people friendly. Because you make streets like this possible:

Why is narrowness so important? Because it is the best way to calm auto traffic and create a truly comfortable, safe experience for pedestrians. Narrow road with narrow lanes create "friction" for drivers - things that demand more attention from the driver, which makes them drive slower and thus help the street become more livable. This gets at a guiding principle that is crucial to the design of streets, but has sadly been a blind spot for departments of transportation across the country for decades: the principle of risk homeostasis. Risk homeostasis is the idea that humans adjust their behavior to maintain a moderate and acceptable level of risk. This is powerful for city streets because streets that feel the most risky to drivers (i.e. narrow, drivers passing closely in the other direction, people crossing, bicyclists nearby) turn out to be the safest streets for everybody. 

Unwalkable Cities

DOT's have historically gotten this exactly wrong. They have flooded cities with multi-lane, single-directional, overly wide streets not only to prioritize auto travel, but because they think this is the safest option. It simply isn't true. Why not? Because overly wide lanes and excessive number of lanes with few obstacles lead drivers to drive faster and be less attentive. Risk homeostasis allows you to predict this behavior; these wide, single-directional lanes feel less risky to drivers, therefore they adjust their behavior by driving faster. These types of streets lead to terribly unsafe and unwalkable cities. Take a look at a typical downtown block of one of the country's worst offenders, Salt Lake City:

That looks like at least six lanes, all very wide. Again, this is a typical downtown block, and the street has been designed to act as a highway. It is pictures like this that should cause traffic engineers to lose sleep at night as they lament their sins. 

Key Ingredients of Great Cities 

Now that we've seen the good and the bad, let's return to the key characteristics from above and quickly discuss why they are key. 

1. Streets exist within a traditional gridded network, forming a pattern of streets and blocks.

Having seen what good and bad streets look like from above, most of these steps should now be self-explanatory. Streets should exist within a grid because this creates the highest level of connectedness. There should not be any two points in a city that a pedestrian can't access easily in a straight (albeit zigzagging) line. A grid accomplishes this. 

The antithesis of a grid is the cul-de-sac that most Americans know all too well. It is our proudest invention of disconnectedness, and it looks like this:

This road layout is one of the main culprits in forcing us into cars. Pick two points that are geographically close but not directly connected. Now determine a route to get from Point A to Point B. That route is circuitous, long and thus only feasible in a car. And even if it were technically walkable, it wouldn't be a safe or pleasant walk because at some point, based on the hierarchy of suburban road capacity, you will be turning off of a quiet, residential street onto a bigger, collector road, then possibly onto an even bigger arterial with cars going 40 m.p.h. or more. The lesson here for designers of cities is: stick with the traditional grid. 

2. Block lengths are 300 ft. or less

Shorter blocks creates a finer-grained network, and not only gives pedestrians better A-to-B access, but creates walking options, and exposes the walker to more shops, restaurants and cafes, which leads to more interesting walks. Instead of having no choice but to walk down one of Salt Lake City's 600 ft blocks, what if you had Portland, Oregon's 200 ft blocks and could choose to turn right at a new block or continue straight? Your walking experience would be more interesting, safer and more useful.

3. Narrow streets, with lanes 10 ft wide or less, and no more than three lanes total (one travel lane in each direction plus a middle turn lane).

We discussed the importance of narrow streets and narrow lanes, and how they lead to safer, calmer and more walkable environments. We touched on the importance of multi-directional travel in the context of safety, but it turns out there's another reason smart cities are converting one-way streets into two-way streets: two-way streets are better for businesses. Imagine driving downtown in a network of one-way streets. Let's say you approach an intersection and to your left you spot a restaurant you'd like to patronize. The problem is the cross-street is a one-way, and that one direction is right. You quite literally can't get to that restaurant unless you are willing to make a complicated series of turns that ends up with you in front of the restaurant by way of an incredibly circuitous route. That's a major hassle full of lots of pointless driving, which probably led to you saying "screw it". Studies bear this out. When streets are converted from one-way to two-way, business revenue goes up. Cars drive slower. Urban congestion decreases. More two-way streets means easier access to businesses, and more cars stopped at intersections, which gives drivers more scanning time. And again, above all else, two-way streets are safer for drivers and pedestrians than one-ways.

4. No crosswalk buttons
The last key ingredient might seem a bit odd: great cities don't have crosswalk buttons? Why not? The answer is subliminal messaging. A crosswalk with push buttons for pedestrians sends the following message: "This street is for cars until you ask them permission to cross." Remember how we discussed that one glance can quickly tell you whether a city prioritizes cars or people? Cross walk buttons mean cars get priority. Since peds always have to push a button to cross a street, they are always guaranteed of waiting to cross the street. For cars, it's the other way around: they drive unimpeded through green-lit intersections until told otherwise. A city that puts people first has no crosswalk buttons; when someone gets to an intersection, sensors tell the stop lights to turn red and the walk sign lights up. No waiting. And brace yourself for this next part: the safest, most walkable cities have a culture of jaywalking. Jaywalking, widely adopted, as it is in NYC and elsewhere, sends the message that streets are primarily for people and cars better be on the lookout. This is a positive psychology for a city to have. Risk homeostasis once again helps explain this paradox. If a driver knows that pedestrians might cross in front of them at any point, they are going to drive slower and be much more attentive in order to maintain a comfortable level of risk. This is in fact what happens in cities all over the world, and helps explain why New York is a walker's paradise. The psychology of pedestrian priority is why car companies invented the term jaywalking and helped criminalize it. They knew it would send the message that streets are for cars first and everyone else second. Cities are beginning to understand the importance reversing that psychology.

The Next Chapter

Phew, that was tiring. If you made it this far, hopefully you have a better understanding of the importance of good design of the public realm in cities. This is possibly the most important element that city planners can get right, because it is the element they have the most control over. There is, of course, the other side of the coin: the private realm. This is where the city is actually built and where it ultimately takes shape. The private realm is the meat and potatoes of city-building, and as you can imagine, it has the power to change the form, function and feel of a city for better or worse. In Part 2 of this two-part series, we will discuss how the private realm is utilized to create great cities full of great streets. 

----Nick Etheredge

Nick Etheredge  is a new contributor to Hug The Rhino who writes about better living in cities, urban living, and how all of that relates to sustainability and social justice. Nick is a Mechanical Engineer who has a strong passion for cities and urban design . Live in or near a big city? You’ll love his articles.