# Chapter 7: Design Principles _Note: This chapter represents work in progress. While the four essential rules in Chapter 6 are based on completed analysis of hundreds of neighborhoods, the design principles presented here are still being refined through ongoing research. We're sharing this "working paper" version to give readers insight into the broader framework, with the understanding that specific measurements and recommendations will be updated as our analysis continues._ --- If the four essential rules provide the DNA of good urbanism—the universal constants that appear everywhere—these design principles represent the art of adaptation. They're how universal patterns respond to local conditions, creating the infinite variety we see in great places worldwide. Unlike the rules, which are measurable and nearly universal, these principles require interpretation. They're not about right or wrong, but about better or worse given specific contexts. They address the questions that arise once you've committed to proper block sizes, rectangular geometry, appropriate street widths, and alleys: How should these elements combine into a complete street network? How should they respond to topography? Where should parks go? What happens at the edges? These principles emerge from the same empirical approach—studying what works—but they reveal patterns of successful adaptation rather than universal constants. They show how the permanent framework can flex without breaking. ## The Art of the Street Network A master street plan is more than a collection of properly sized blocks—it's a complete network that must balance multiple objectives: connectivity, orientation, character, and adaptability. While blocks might be the cells of urbanism, the overall street pattern is the skeletal structure. Our analysis reveals that successful street networks tend to fall into five basic patterns, often in combination: 1. *Rectilinear Grids* (regular rectangles and squares) 2. *Angular Grids* (straight streets at varied angles) 3. *Diagrammatic Plans* (expressing a single organizing idea) 4. *Curvilinear Networks* (following contours, garden suburb) 5. *Irregular Patterns* (organic evolution over time) Importantly, all the successful examples we studied follow the four essential rules regardless of their overall pattern. Bad street networks—the ones that create unwalkable, unadaptable places—violate those rules. This section examines only successful patterns and their relative merits. ### Rectilinear Grids The rectilinear grid dominates American city planning for good reason: it works. From Philadelphia to Portland, from Manhattan to Main Street America, the regular grid has proven itself across centuries and contexts. Critics dismiss grids as boring, viewing them from 10,000 feet and imagining monotony. This fundamentally misunderstands how cities work. The grid doesn't determine character—it enables it. New York, Chicago, San Francisco, and New Orleans all use regular grids. No one visiting these places complains of monotony. The grid's true genius lies in its neutrality. Every block is equally accessible. Every lot has similar potential. No location is privileged by the plan itself. This democratic framework allows market forces, culture, and time to create differentiation. The most valuable corner emerges through use, not predetermined design. **Advantages of rectilinear grids:** - *Maximum connectivity*: Multiple route options between any two points - *Intuitive navigation*: Never get lost when streets follow a consistent pattern - *Efficient land use*: Rectangles maximize buildable area and minimize waste - *Adaptable over time*: The same block can host farms, houses, or skyscrapers - *Economical to build*: Straight lines are the shortest distance between two points - *Easy to extend*: The pattern can grow in any direction **Potential drawbacks:** - Can ignore topography if slavishly applied (though San Francisco proves grids can work on hills) - Long views down streets may lack visual termination - Requires conscious effort to create special places within the neutral framework The key insight: grids aren't boring—they're blank canvases. What matters is what gets painted on them. ### Angular Grids Not all grids meet at right angles. Angular grids—what we sometimes informally call "stained glass" patterns—use straight streets that intersect at varied angles. These often develop organically as different property lines, survey systems, or existing roads create a patchwork of geometric shapes. **Advantages of angular grids:** - *Visual variety*: Closed vistas and changing views create discovery - *Natural hierarchy*: Irregular intersections create obvious locations for special buildings - *Unique lots*: Triangular and trapezoidal lots can accommodate special uses - *Responds to existing conditions*: Can incorporate old roads, property lines, and natural features **Potential challenges:** - Acute angles create difficult building sites - More complex to navigate than regular grids - Requires more sophisticated design to avoid leftover spaces ### Diagrammatic Plans Some cities embody a single powerful idea: radial boulevards converging on a center, concentric rings expanding outward, linear spines following geography. From Renaissance ideal city plans to Garden Cities to contemporary New Urbanist communities, these designs make a clear formal statement. The danger is that cities aren't diagrams—they're living organisms that grow and change in unpredictable ways. A radial plan assumes the center remains central forever. A linear plan assumes growth continues along the predetermined axis. When these assumptions prove wrong, the rigid diagram can become a straitjacket. Yet when done well, when embedded with sufficient flexibility in form, diagrammatic plans create memorable, imageable cities. Paris's radial boulevards, Savannah's ward system, and Back Bay Boston's spine all demonstrate how a strong organizing idea can enhance rather than constrain urban life. Washington, DC, too. L'Enfant's diagonal avenues slice through a regular grid, creating a rich variety of triangular parks, complex intersections, and dynamic spatial sequences. The result maintains the connectivity benefits of a grid while adding visual interest and creating natural locations for civic monuments. **Keys to successful diagrammatic plans:** - Build in flexibility for growth beyond the original diagram - Ensure the organizing idea enhances connectivity rather than limiting it - Don't let the diagram override the fundamental rules of block size and street width - Recognize that the diagram is a starting point, not an ending point ### Curvilinear Networks Curving streets follow two basic impulses: working with topography (following contours) or creating aesthetic effects (the picturesque suburb). Frederick Law Olmsted pioneered this approach in America, designing suburbs like Riverside, Illinois, with gracefully curving streets that created a park-like atmosphere. When curves follow natural features—rivers, ridgelines, slopes—they make perfect sense. The street bends because the land bends. But arbitrary curves on flat land often create more problems than they solve: disorientation, inefficient lots, and wasted land. Guidelines for successful curvilinear networks: - Let topography drive the curves, not aesthetics alone - Maintain connectivity—curves shouldn't create cul-de-sacs - Keep curves gentle enough to maintain efficient lot shapes - Consider mixing curved and straight streets rather than universal curves ### Irregular Patterns The "organic" patterns of medieval cities evolved through centuries of incremental decisions. What oftentimes started as Roman grids got pushed and pulled by individual property owners, defensive needs, and topographic constraints into complex, irregular networks. While we can't recreate centuries of evolution, we can learn from these patterns. They demonstrate how frameworks adapt over time, how public and private negotiate boundaries, and how apparent chaos can mask underlying order. ## Lot Sizes _Research in progress: Our ongoing analysis examines the relationship between lot dimensions and adaptability across different contexts. Initial findings suggest optimal lot dimensions cluster together, but more data is needed before making specific recommendations._ ## Parks and Civic Spaces _Research in progress: We are currently analyzing the size, distribution, and integration of parks within successful neighborhoods. Key questions include: What percentage of land should be dedicated to parks? How should parks be distributed? What sizes work best? This section will be updated as our analysis continues._ ## Responding to Existing Conditions No site is a blank slate. Every master street plan must respond to what's already there—both natural systems and human infrastructure. The question isn't whether to respond, but how. ### Natural Features *Topography*: Steep slopes demand respect. While San Francisco famously ran its grid straight up hillsides, most cities benefit from working with contours rather than against them. Streets running along contours provide gentler grades; those running perpendicular create steeper but more direct routes. The key is finding the right balance for your context. *Water*: Rivers, streams, and shorelines are both barriers and amenities. The principle: cross water as often as feasible to knit both sides together. Chicago's numerous river bridges demonstrate how frequent connections prevent a river from dividing a city and can turn it into a focal point. *Views and Solar Orientation*: Great views and optimal solar exposure are resources to be shared, not hoarded. Street patterns can ensure more lots have access to these amenities rather than allowing the first row to block everyone else. ### Human Infrastructure Modern cities must also respond to infrastructure that divides: highways, railroads, airports, utility corridors. The same principle applies: create as many connections as possible. Every grade separation is expensive, but the cost of a divided city is higher. Where barriers can't be crossed, they can sometimes be covered. Boston's Big Dig, Seattle's freeway lid parks, and numerous rail deck developments show how divisive infrastructure can be transformed into connective tissue. ## Extra-Territorial Considerations Master street plans stop at jurisdictional boundaries, but good planning shouldn't. The edges of your plan must anticipate connection with whatever lies beyond—future development, other jurisdictions, or rural lands. _Research in progress: We are developing best practices for edge conditions, including stub-out strategies, shared boundary streets, and coordination mechanisms. This section will be expanded based on case study analysis._ ## Using Design Principles These principles aren't rules to be mechanically applied but considerations to be thoughtfully balanced. Every site, every community, every context requires its own synthesis. The art lies in knowing when to grid and when to curve, when to assert geometry and when to defer to topography, when to create uniformity and when to introduce variety. Sometimes, based on existing conditions, those decisions will be made for you. The trick is knowing when to let it happen or when to push back. What matters is that these decisions build upon the solid foundation of the four essential rules. Get the blocks right, make them rectangular, size the streets properly, include alleys (or at the very least ensure you have your "fronts and backs" right)—then apply these principles to create places that are both universally functional and locally distinctive. The next chapter will show how these rules and principles apply to different development contexts, from greenfield sites to urban infill. *** Continue to [[Chapter 8 Etc]] →