Urban design expert Jeff Speck -- who has made repeated appearances in Des Moines -- says transportation engineers often see every new street as a chance to build a highway. 
That's a mistake in an era when streets need to be designed to meet diverse community needs, including the ability to walk through an area without crossing four to eight lanes of speedy traffic. 
Speck, who runs his own consulting firm and teaches at Harvard University, writes in a blog post in The Atlantic: "Even when traffic engineers have the best intentions, too many simply lack the tools to make successful places. In the typical American city, asking a traffic engineer to design a walkable street is like asking a hammer to insert a screw."

Speck, who is based in Brookline, Mass., argues something that he admits seems obvious: Communities interested in a certain goal, like making it easier for bicyclists or walkers to get around, would do well to mimic models that have worked. That will mean standing up to "traffic counters," who, in Speck's view, "always win."

"City planning is not just an art, but also a profession, and like in the professions of law or medicine, its practitioners have a responsibility to learn from past successes and failures," Speck wrote. "Study of precedent makes it clear that boulevards create street life and enhance real estate value, while highways obliterate street life and sunder real estate value."

"... All of our cities, as they contemplate expensive reconstruction of obsolete roadways, have two models to choose from, one led by engineering, and another led by precedent: the study of places we love."