Pervious Pavement and Street Width in Portland

I was visiting some friends in Portland when I happened upon some unique paving. Instead of the street consisting of one solid slab of asphalt, the asphalt was limited to the narrow travel lane. The parking lanes were paved with brick-colored pavers. After I returned home, I did some research and found that this was a City of Portland, OR pilot project to test a couple of pervious paving schemes.

Portland’s pervious paving experiment

The street above is one of a few the city did in the Sellwood/Westmoreland neighborhood to mitigate the effects of storm water runoff after heavy rains. Portland has been on the forefront of storm water mitigation at the source, but usually through the use of bioswales. This treatment allows rainwater to flow off of the asphalt and into the parking lanes, where high-strength concrete pavers allow rainwater to flow down the spaces between them. The layers below the pavers filter out pollutants that would otherwise contaminate the groundwater.

While I really like this approach to managing storm water, I am most interested in this as a bit of urban design. This street looks like it is about 30 feet curb-to-curb, with two eight-foot parking lanes, two one-foot curbs between the lanes, and about twelve feet of asphalt for the queuing travel lanes. The idea on this street is that when two cars pass each other, one slows or stops in the parking lane to allow the other to pass. It’s a condition that results in slower speeds, perfect for residential neighborhoods like this.

This scheme really makes the street feel narrower and more appealing. A 30-foot-wide street on a quiet residential block is a bit overkill and out of scale for the place. Reducing the ocean of asphalt to a pleasant strip is a step in the right direction. The addition of pavers adds some human-scale texture to the street — another plus.

The same street, with less on-street parking

The scheme also highlights an absurdity in residential street design. Namely — does this street really need two sides dedicated to off-street parking? Taken together, parking takes up over half of the street area and it’s used by maybe three cars in this picture. In places where there is plentiful off-street parking, this much on-street parking seems like a waste. The different pavement treatments really shows off this ridiculous allocation of space. Imagine if one side of the parking was removed, and the curb-to-curb width was only 22 feet (the quick photoshop at right). The result is much more intimate and better proportioned to the area the street serves.

Even with the street at the present width, the new pavement treatment is a success on a couple of levels. The storm water entering the sewer system will undoubtedly be less, and the street is far more attractive than a plain asphalt-only one. It’s not within the City of Portland’s capabilities to stretch the fabric of the earth to reduce the width of the street like I did above, but it shows that new streets do not need to be built to the same specifications.

The Texture of Streets

In a recent post over at New World Economics, Nathan Lewis posted a series of photos of great urban streets (see one below) and asked: “Does the place you live/work/shop look as good as this? Why not?” He’s making the obvious point that most people don’t interact with spaces like this on a daily basis, at least not in the United States. There are many reasons for this; Lewis looks at the economics behind it, which makes sense as he’s an economist. I’m an architecture and urban planning student, so I’m interested in the design of these spaces. What about those streets makes them universally appealing?

Quebec City, Canada via Nathan Lewis

As the title to this post has indicated, the texture along the street is what makes the street in Quebec City and the others so appealing. Just look at the picture to the right. Check out at all of the signs, balconies, awnings, stairs, and vines. All of these elements create a visually interesting space for our eyes; we could walk up and down this street many times without being bored. There are plenty of windows, as well, for looking into. Many of the elements, like the window displays, awnings, and landscaping, change with the seasons. Furthermore, all of these elements are designed for humans passing by at walking speed. Signs are placed just high enough so that they can be seen above the heads of other people along the street. In a typical suburban strip mall development, the signs are incredibly high so that speeding motorists can see them from a mile away. Of course, this street is helped because there are no cars on it at all. Cars are big and streets designed for only them tend to be incredibly ugly for pedestrians. I guess the hope is that in a car you’re moving by so fast you don’t notice.

Wells Fargo Center, Portland, OR

This poor attention to human detail even occurs in the downtowns of America’s cities. These are places that originally were the bastion of pedestrians, but in many places have become wastelands. The picture at right is an example of what happens when architects stop designing for humans. Instead of thinking about the texture of street level, the architects cared more about how their skyscraper would look as a piece of modernist art. Thankfully, due to this building, the city of Portland requires that a majority of a facade at street level be transparent. This means that some form of retail will occupy street level, with the hope of creating more pedestrian-level texture.

Texture is only one element of a beautiful city street, but without it a street can’t truly be successful for pedestrians. It’s the primary indicator that people are welcome, not (just) cars.