Cyclists paved the way for cars. Literally. Long before the masses embraced internal combustion and took to the highways and byways on four wheels, cyclists were lobbying for paved roads. If you often ride on gravel or dirt you’ll know why. When you’re going somewhere on your bike—as opposed to simply killing time on singletrack between airings of the X Games—you soon learn to value a smooth, hard, stable surface. But the freedom of the paved road isn’t free. Asphalt and concrete slab surfaces are, for all practical purposes, impermeable. And when heavy rain falls on a well-engineered, impervious roadway (or shopping mall parking lot), the water does what comes naturally: It runs off immediately, swelling local streams to flood stage and overwhelming urban sewer systems.
From the narrow perspective of a highway engineer, this is a very good thing. You don’t want your roads turning into rivers, after all. But environmental geologists look at things differently. If you prevent rainwater from soaking into the ground, you impoverish local aquifers. And when you then hustle that water into the nearest river or stream as fast as possible, you increase the damage done by shoreline erosion, as well as raising the probability of catastrophic flooding farther downstream. In the past—and all too often, even today—highway engineers have seen this as somebody else’s problem. Their job was to keep the roads open to travel. Preventing floods and shoreline erosion wasn’t part of their job description.
But things are changing. Extreme weather is becoming commonplace everywhere. Torrential rains now follow hard on the heels of prolonged droughts, and impervious paved surfaces make both extremes worse. As we pave more and more of the earth’s surface, less and less water is returned to the underground reservoirs that feed our wells and reservoirs, leaving us more vulnerable to drought. And as we build more and more paved roads, we direct ever larger amounts of runoff into neighboring streams and rivers. This increases the likelihood of destructive urban flooding. It’s a lose-lose scenario.
Of course, even highway engineers like to see water coming out when they turn the tap. (Some of them own shoreline property, too.) So they’ve started to consider alternatives to impervious asphalt and concrete slab paving, and this has led them to take a second look at one of mankind’s oldest building materials: the common brick.
Needless to say, some folks are more receptive to new ideas than others. While I don’t see much pressure for constructive innovation in my own backyard—”We like it the way it is” has been the local motto for as long as I can remember—that’s certainly not true everywhere. Marcos Netto, TNO‘s Southern Hemisphere Correspondent, lives in southern Brazil, and when I first saw his son’s photo of Paralympian João Correa and his “guardian angels“ …
I couldn’t help but notice that the pavement under João’s wheels looked like brick. And Marcos—he’s the tall “angel” in the center of the picture—quickly confirmed that my eyes hadn’t deceived me. Here’s what he had to say:
Those are cement bricks. They are manufactured using conventional cement and are available in various shapes. The most common ones are either rectangles, hexagons, or an almost S-like shape, achieved with the use of one rectangle and two squares.
The bricks are all laid by hand by companies which specialize in it. The price is based on the square meter, and it's as much as 30 percent cheaper than asphalt. After laying, and assuming no heavy traffic rolls over the bricks, the paved area will remain in place for decades. If the area has fertile soil below the bricks, grass might grow between them, making it a lot more interesting to look at.
Bricks are used mostly for parking lots and areas where there is no heavyweight vehicle traffic, but for a long time I've seen them on some streets where they've suffered no significant damage. The only real problem is when there's a need for underground work to repair some gas, phone, or sewage lines. The bricks must be removed before excavation, and even with careful work they will never be replaced the same way, which is visible on the street or parking lot.
There is another version of brick paving for high-impact traffic areas. This involves intensive preparation of the base where the bricks will be laid, making the underlying ground weight-resistant.
You are right about the advantages regarding water on brick paving. Bricks make evaporation and ground absorption faster, thus making it less expensive to install drains in the area.
Now here are some more examples of brick paving:
OK. What’s not to like? Brick paving combines beauty with utility and economy, which makes it a very attractive option for parking lots, town squares, and low-traffic residential streets. Of course, it won’t offer cyclists as smooth a ride as new asphalt, but I’d be more than happy with the trade-off if it meant that the water kept flowing from my tap and fewer homes (and businesses) were lost to floods. What about you?
- “Brick,” a Wikipedia primer on this ancient building material, plus …
- “Block Paving,” another Wikipedia article, short but informative, and finally, …
- “Permeable Paving,” Wikipedia‘s take on the big picture. It seems that brick isn’t the only option.
Questions? Comments? Just click here!