Confessions of a Recovering Engineer. Charles L. Marohn, Jr.

decision on whether a transportation investment is a street or a road is not a technical one. It requires knowledge of the community's goals and objectives, but no technical expertise regarding engineering or design. This is a decision that must be made by an elected body — one directly accountable to the people of the community. It should never be made by technical professionals.

      If we leave this decision to traffic engineers and transportation planners, the result will almost certainly reflect the embedded values of their professions. An emphasis on speed and volume creates tradeoffs between mobility and access, a tension that technical professionals inherently address by prioritizing speed. It does not take much in terms of added speed to make a street into a dangerous and unproductive stroad.

      If State Street were designed to be a street and not a stroad, it is very likely that Destiny Gonzalez would still be alive.

Productive Stroads

      I started to develop my understanding of the difference between a street and a road as a teenager visiting Disneyworld. The theme parks and resorts are fantastic places. People pay thousands of dollars to spend time in them. If you stay in one of their resorts, you can walk to everything you want or need, including shops, restaurants, and recreation. The attention to detail in designing those human spaces impressed me as a young man and continues to do so today. These are great places that create enormous wealth for the Walt Disney Corporation.

If you are in Disneyworld in one place and want to visit another place — say a theme park, one of their shopping districts, or another resort — you can quickly drive there on roads that are unencumbered by excessive amounts of traffic, despite the incredible number of people being transported on them. Part of this is because there are almost no stops along the way. All of the complexity has been removed and what is left is high speed and simple to navigate.

      Another reason for the productivity of the roads is that most people do not drive but instead take another form of transit. This could be a bus, monorail, boat, or even an aerial gondola. These systems carry huge numbers of people between productive places, quickly and efficiently, where those people then exit the transportation system and immerse themselves in their place of destination. It is not lost on me that the most successful pre-automobile cities were built in this way, with the roads connecting them being waterways and railroad lines.

      It was on my first trip to Paris in 2001 that I experienced a different kind of stroad than what I had come to know from living in North America. One of the most iconic streets in the world, the Avenue des Champs-Élysées, was a stroad back then. It combined the function of both street and road, building wealth and moving traffic, but it did both exceptionally well. The Champs-Élysées is one of the wealthiest and most exclusive streets in all the world.

      This productive stroad trick was accomplished with what an engineer would call a slip lane. The outside lanes of the Champs-Élysées, those closest to the buildings, were designed to be streets. There were slow speeds, parking, street trees, and an emphasis on people. In fact, people walked back and forth across these lanes all the time, an indication to me that Parisians and the tourists flooding their city felt secure in this space.

      The middle lanes of the Champs-Élysées, the road portion of the stroad, were separated from the slip lanes by wide, tree-lined boulevards. There was physical separation between the street portion and the road portion. This allowed the traffic in the middle to operate safely at relatively higher speeds. (The Champs-Élysées was no highway, but it would not surprise me if traffic safely reached speeds of 45 miles per hour on the road portion.)

      The ability to cross the Champs-Élysées was the only real impairment, something for which long delays in signal timing could somewhat compensate. When it was time for people to walk across, they were given a fairly long time to make that crossing. When it was time for drivers to operate their vehicles, they were likewise given a long turn at dominating the space. I was deeply impressed.

Years later, I visited the great incremental developer R. John Anderson when he was living in Chico, California. There he introduced me to the Esplanade, a two-mile stroad through a gorgeous neighborhood. It was a more modest version of the Champs-Élysées, with the interior road lanes physically separated from the street slip lanes by a tree-lined boulevard. The neighborhood along the Esplanade is a great place that makes for pleasant walking, a fact reflected in the high property values.

      Five blocks east is Mangrove Avenue, a nasty stroad that runs parallel to the Esplanade. Mangrove Avenue has the gas stations, strip malls, and other auto-oriented businesses typical of American strip development, a style not only less productive financially but far more fragile than that found along the Esplanade. In 2018, both stroads accommodated around 22,000 vehicles a day, despite the radically different design and outlook.

      The Champs-Élysées and the Esplanade are exceptions to the norm, but I include them here because they are not only good models to understand, they reinforce the notion that the critical tradeoff is not between access and mobility but between street and road, between building a place and traveling between places.

      Incidentally, I had the opportunity to visit Paris again in 2019. This time my wife and I were joined by our daughters. In a way that I am sure is doing long-term psychological damage to my children, I was excited to show them the layout and design of Paris, including the slip lanes along the Champs-Élysées. After building them up to my family and eagerly anticipating them myself, I could not find them anywhere. They were gone.

      All the street space that was formerly used for parking and slow-speed driving has now been given over to people on foot. Parisians have wisely decided that the area surrounding the Champs-Élysées is far more valuable when a high number of people can access it on foot, as opposed a lesser number of people accessing it by automobile. Successful experiments in limiting or banning automobiles in parts of the core of Paris are extensions of this realization. The Champs-Élysées is no longer a stroad.

The idea of banning automobiles today on State Street in Springfield is an absurdity, as it is for almost all stroads within North American cities. Our neighborhoods are simply not valuable enough as places either to warrant or sustain themselves without some automobile access. Yet achieving that level of wealth and productivity must be the goal.

      Building great roads and productive streets is ultimately about making the places we inhabit so prosperous, so productive, so valuable, and so inviting that they transcend the need to accommodate the automobile.

      The Walt Disney Corporation would never make Cinderella's castle in the Magic Kingdom accessible by car. Whatever added value there is from being able to drive right up to the castle would be dwarfed by the lost value from individual automobiles diminishing the overall experience of the park itself. The park is such a valuable place, the streets within it have created such wealth, that it only needs roads to connect it to other places to thrive.

      Springfield is not a theme park. It is a city where people live, work, and occasionally take their kids to the library. The automobile is going to be a reality along State Street for years, likely decades, to come. A reality, but not the goal.

      The goal must be to turn the stroad of State Street into a wealth-producing street. That will require a shift in emphasis from moving traffic to building a productive place — one focused on the needs and experiences of the people who live there.

The Strong Towns Approach

      Roads are high-speed connections between productive places. Streets are platforms for building wealth within a place. The greatest value in a transportation system is provided when building roads or streets.

      A stroad is a street–road hybrid. It contains the elements of both road and street but fails to provide the benefits of either. Stroads are expensive to build and maintain and have low financial productivity. The complexity of the stroad environment combines with high traffic speeds to create environments that are extremely dangerous.

      Cities must discard the hierarchical transportation networks and instead identify their streets and their