How a municipality is designed can create elegance or chaos

John Conti
| Sunday, Jan. 22, 2012

In New York City this past year, they've been marking the 200th anniversary of Manhattan's grid.

Here in Western Pennsylvania, by contrast, folks in Mt. Lebanon this year will be celebrating the 100th anniversary of the suburb that ultimately broke Pittsburgh's relentlessly expanding grids.

Grid• Grids• What exactly are we talking about?

Well, the grid is something you always see but never notice. It's the layout of streets in neat perpendicular patterns. A grid has regular blocks, often of similar sizes, with easy-to-number streets and easy-to-identify intersections.

It's the world's oldest city-planning device and has been in use since before the days of the Greeks and Romans. It has shaped both cities and small towns in the United States. Grids can provide elegance or boredom, great vistas or stultifying "mean streets" depending on how a town uses them.

In Pittsburgh, we actually do much of the world one better. The compact center of our city -- our Downtown -- actually has two grids. Unfortunately, they don't meet neatly, making it difficult sometimes to give directions Downtown.

It's fun to speculate that this conflicting pattern, dating to the late 1700s, might have started the Pittsburgh tradition of giving directions by way of landmarks rather than street names. You know, the sort of thing that can drive newcomers crazy, such as "turn right where Isaly's used to be."

Still, nothing so momentous as the shape of our streets should ever be taken for granted. So, let's take a look at some of the implications of "the grid," starting with Manhattan and Pittsburgh and ending with Mt. Lebanon -- where 20th-century suburban neighborhoods developed from grid-busting curvilinear designs for 19th century cemeteries and parks.

In many cities, grids were laid out perpendicular to waterfronts. That's what happened in both Manhattan and Pittsburgh. In Manhattan, numbered cross streets (like 42nd Street) run in a neat straight line from the Hudson River to the East River. Numbered avenues (like Fifth Avenue) divide them, running roughly north to south.

In Pittsburgh, though, our rivers form a triangle, so one grid was laid out perpendicular to the Monongahela, while the other grid matched the Allegheny. Liberty Avenue is where the two grids meet.

It's possible in Manhattan to stand at the corner of First Avenue and 1st Street, pick any numbered avenue or any numbered street and know exactly how to get there. Not so in Pittsburgh. Here, if you look across Liberty at the end of Sixth Avenue you see Seventh Street.

What saves Manhattan from monotony -- as a current exhibit on "the grid" at the Museum of the City of New York makes clear -- are two things. One is Broadway, which runs the length of the island, often at angles, creating memorable spaces like Times Square. The other is Central Park. The park wasn't in the original plan for the grid in 1811, but city planners wisely decided 40 years later to provide for it.

Downtown Pittsburgh's two grids may be confusing, but our topography makes up for it. Look down our streets wherever they go toward the rivers, and you see compelling vistas of hillsides in either direction. Green hillsides in the summer are notably rare in major cities.

There's more. If you look down Fifth Avenue from, say, Macy's, Fifth Avenue Place looms at the end of the street, closing off the view. That's because the avenue is aligned with the Monongahela grid, while the building is aligned with the Allegheny one. The same thing happens on other streets Downtown. This is not bad at all, as the closed views give these streets a special sense of place. In short, our Downtown gives you two key spatial experiences: vistas at some points and enclosure at others.

As Pittsburgh expanded from Downtown in the 1800s, it continued with an unrelenting collection of unrelated grids, often built between hillsides, sometimes in spite of them. The Strip, the Hill, Oakland, East Liberty -- all have their own grids. Grids are efficient and encourage rapid development.

As the city's growth reached the South Hills in the early 1900s, developers imposed grids on some of the roughest terrain in the region. This is why there are so many steep hills in Beechview, Brookline and Dormont. Canton Street in Beechview is so steep the city won't let you drive down it (you have to drive up). Its 37 percent grade -- it drops 37 feet for every 100 feet -- is said to be the steepest in Pittsburgh.

This grid pattern continued into parts of what is now Mt. Lebanon. But, it was, eventually, supplanted there by curvilinear streets that reflected a "naturalistic" style for suburban design. Mt. Lebanon neighborhoods such as Mission Hills and Virginia Manor were designed in the 1920s using comparatively level curving roads laid out to go along with, rather than fight, the contours of the hills. This style suited the automobile, and by the 1950s virtually all suburbs were being built, for better or worse, with curvilinear roads.

Interestingly, this decisive change is owed in part to public enthusiasm for 19th-century cemeteries and, later, public parks that introduced this naturalistic landscape style to the United States. One influential early proponent of the style -- for both suburbs and parks -- was Frederick Law Olmsted, who, in the 1850s, took the lead in designing Manhattan's Central Park -- the greatest grid-buster of them all.

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