Monthly Archives: August 2014

Road Diet Bibliography

By Dom Nozzi

Recently, I prepared a “Transportation White Paper” for a local advocacy group. One question I got was whether I could cite any cities (either in the U.S. or abroad) that have downsized city streets via a “road diet,” where travel or turn lanes are removed?  The person noted it was always good to have precedents when something is newly proposed, and also good to know the results when the proposal was tried elsewhere.

With that request, I went ahead and prepared the following citations regarding studies pertaining to road diets in America.














  • Welch, T. “The Conversion of Four-Lane Undivided Urban Roadways to Three-Lane Facilities.” Presented at the Transportation Research Board / Institute for Transportation Engineers Urban Street Symposium, Dallas, TX, June 28-30, 1999. [reduced crashes, traffic calming enhanced, improved emergency vehicle response times]




Another question someone asked me about my draft White Paper was whether there was any scientific data that shows that reducing a four-lane street to three lanes (a common form of road diet) has very little impact on congestion or traffic delays?  The questioner understood the argument, but I’d like to see some empirical data. Here is the list of studies I prepared for that question.







  • Welch, T. “The Conversion of Four-Lane Undivided Urban Roadways to Three-Lane Facilities.” Presented at the Transportation Research Board / Institute for Transportation Engineers Urban Street Symposium, Dallas, TX, June 28-30, 1999. [reduced crashes, traffic calming enhanced, improved emergency vehicle response times]


A final question from the advocacy group regarding my draft White Paper road diet before and afterwas:  “Where do we go from here?”  This person noted that the group was likely to get enthusiastic support for road diets from bicyclists, but “may” lose credibility with the much-broader middle class of drivers in the community.   It’s going to be an uphill battle, according to this person, to convince drivers that less parking and more congestion is a good thing.


My response was as follows…


In my experience, right-sizing streets (or “re-purposing” streets) typically meets with opposition from business owners and other citizens – particularly regional commuters. However, right-sizing almost invariably results in such substantial, rapid improvements in business and residential climate, crash road_diet_examplereduction, absence of feared congestion increase, and improved quality of life that the initial opposition tends to quickly change to broad support. Indeed, In Seattle WA, road diets resulted in such obviously beneficial outcomes for businesses and residences along the dieted streets that property owners on two other arterial streets asked for the road diet treatment on their streets. Overall, Seattle has completed over 30 road diets, according to Peter Lagerwey. Therefore, right-sizing streets is a matter of political leadership. Those communities with leadership are successfully able to substantially improve their community. Those without such leadership fail to enjoy such success.

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Filed under Road Diet, Urban Design

“Concurrency” for New Development?

By Dom Nozzi

“Concurrency” is a regulatory rule that seeks to ensure that new development does not result in a diminishment of the amount of parks or schools or potable water per person. Some communities call it an “adequate facilities” rule.

I worked as a town planner for 20 years as a long-range comprehensive planner in Florida, and a great deal of my work involved helping my community implement the state concurrency rule adopted a year before I started my job.

This state growth management law goes into great detail and requires an enormous amount of study to determine, precisely, concurrency needs for facilities (primarily adequacy for roads to avoid congestion). The concurrency rule seems, on the surface, to be a good proxy for our determining if we are “managing” growth and protecting our quality of life.

In fact, it is an incredibly bad measure for sustainability and quality of life.

Despite first impressions, the rule tends to move communities in the opposite, downwardly-spiraling direction.

The rule is fairly harmless for, say, parks or schools. But for roads, maintaining per capita road capacity with a concurrency or adequate facilities rule is ruinous.

In most or all instances where concurrency is adopted by a community to manage new development, the rule says nothing meaningful about needing to maintain a level-of-service for the most important elements of a quality community: quality neighborhoods, transportation choice, housing choice, urban design quality, compact development, mixed use, or quality of life.admin-ajax (3)

Instead, nearly all applications of the rule forces the community to divert an enormous amount of time and energy into putting together a huge amount of data that is nearly meaningless for creating quality communities — data that is often counter-productive. And little more than mindless, bureaucratic bean counting.

Because of this, communities with a concurrency rule often have very little available staff time that can be devoted to putting together a vision for quality of life and sustainability. Such communities could have time, but it would require more money to hire more planners — and visionary planners at that. By setting up a concurrency rule, most communities get lowest common denominator planning.

The smaller towns with no planning staff or history of planning are helped to at least start doing something to fight the Wal-Marts and sprawl developers, but for bigger, more sophisticated cities, the rule typically means that planning staff squander a huge chunk of their time on bean counting: working up huge amounts of numbers that don’t help the community — and usually hurts the community.

Almost never does a community with a concurrency rule ask or expect any visioning or designing for quality of life. They are so busy counting beans that they kill themselves to assess concurrency numbers, and then delude themselves into thinking that such a number-crunching effort will somehow give them, magically, a pleasant, walkable town.

We need to start over again on concurrency.

Concurrency must start finding proxies for quality of life.

The road concurrency rule (which is the only concurrency rule that matters for most or all of the communities which have adopted concurrency regulations) means, instead, that all the community cares about is a quality of life for cars.

The unintended consequence of such a misguided focus on a quality car habitat rather than a quality people habitat? The community makes it inevitable that sprawl will be accelerated and the quality of life trashed. Indeed, both sprawl and quality of life end up being much worse than had the community not adopted a concurrency rule.

And what a bitter irony that would be.

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Filed under Politics, Sprawl, Suburbia, Transportation