Mississippi Rebuilding



By Ruth Walker


Lucy Gibson, Vice President, Smart Mobility
The new document on urban thoroughfares produced by CNU and the Institute of Transportation Engineers is not yet recommended practice, and that's probably a good thing.

This was the take-away from Friday's seminar on the document, which has a mouthful of a title: "Context Sensitive Solutions in Designing Major Urban Thoroughfares for Walkable Communities ."

It's not just the title; the document itself is pretty hefty - over 200 pages. "A monster," Norman Garrick of the University of Connecticut, one of the seminar presenters, called it.

Still, he was quick to point out that one of the most important things about it was the partnership that brought it into being: CNU, ITE, the Federal Highway Administration and the US Environmental Protection Agency. The project began with an important meeting in Oakland, Calif., in 2002. It was a meeting when all these players "were all in the same room, and all talking to each other."

The document, now in its public comment period, is intended to build on, and be consistent with, current AASHTO Green Book standards.

However well-intentioned it was, though, Garrick identified some problems:

--The analysis assumes a tradeoff between land access and mobility, and assumes that mobility is vehicular.

--The functional classification of streets it presents fails to recognize certain kinds of successful thoroughfares, such as Connecticut Avenue in Washington, which carries a lot of vehicular and foot traffic. "This street theoretically doesn't exist," he said.

--The document merges the concepts of thoroughfare type with functional classification. All arterials are not the same, for instance; some are boulevards like Connecticut Avenue, while others are highways lined with strip malls.

--The document merges the concepts of "design speed" and "target speed." ("That's like putting on the air conditioning in your house and then putting on the heat," Garrick said.)

--Methodologies for designing limits to speed are still needed. Europeans have identified 20 mph as the appropriate speed limits for pedestrian streets, Garrick said, but on American graphs showing fatality rates over a range of speeds, the scale for speed generally starts at 25 mph.

The ideal is to integrate the mobility and place function of streets. Lucy Gibson, vice president of Smart Mobility, called for a "paradigm shift" away from the dendritic tree branch model of traffic flow in favor of the grid and a recognition that local streets can absorb more of the traffic than they're being expected to.

She presented two maps projecting traffic congestion in Chicago, one counting on the "sprawl" model and one assuming considerable compact, in-fill development. The first showed numerous red splotches, indicating congestion; the other had far fewer.

R. John Anderson, vice president of planning and Design for New Urban Builders Inc., presented two parts of essentially the same street in Chico, Calif., the tree-lined Esplanade, within city limits, subject to a much tighter set of regulations, and its "evil twin" across the line in the county. He argued against seeing "great streets" as something that were built by a "lost race" and can't be duplicated today.

Builders need to understand that if they "create beautifully crafted streets," they'll be able to charge more for property along them, he insisted if only for the safety factor involved when vehicular traffic is held to speeds truly safe for pedestrians. "People will pay extra to save their children's lives."