Tag Archives: crashes

What Do I Think of the Diverging Diamond Interchange?

 

By Dom Nozzi

Febuary 2, 2017

Superior, Colorado built a “diverging diamond” interchange that opened in October 2015. It was only the second such interchange to ever be built in Colorado. Traffic engineers are imagessinging its praises throughout the nation. A newspaper article appearing in the February 2, 2017 edition of the Boulder Daily Camera fawned over the fantastic new addition to the region’s transportation system.

I am not joining the engineers or the newspaper in their love affair with the design.

Instead, I find such designs a colossal waste of money – money that could have been used for, say, transit. They are also a colossal waste of land. An entire city could fit inside one of these intersections.

The diverging diamond is a boondoggle for those reasons. But it is also a blunder because they promote increased per capita car travel. Why? In part because they are nearly 51df393d218c6-imageimpossible to cross by foot or bicycle. And in part because in the long run they will further disperse land development in a more sprawling way. Those increased distances will make it increasingly impractical to walk, bicycle or use transit.

Ironically, the major justification for the car-only design is that it briefly reduce intersection congestion, which will initially save a few seconds of motorist time (think of the fiscal irresponsibility of spending millions of public dollars spent to save a few seconds temporarily). Ironic because by artificially inducing more car trips than would have occurred had the diverging diamond not been built, the design will lead to MORE traffic congestion and MORE time delay for motorists in the long term (both at their location and areas in the region).

To hide the embarrassing fact that the millions spent ($14 million in this case) to briefly save a few seconds of time, the publicly proclaimed explanation is that it will improve safety. For the conventional traffic engineer, “improved safety” actually means that motorists can now drive faster and more inattentively with less fear of crashing. No mention is made of the fact that the intersection is much less safe for pedestrians or bicyclists, or that faster, less attentive driving is very dangerous for everyone.

The diverging diamond, therefore, is an excellent example of the century-long failure by conventional traffic engineers to understand induced car trips that are created by (briefly) reducing traffic congestion with these designs. There is a reason, after all, that many researchers repeatedly urge us to understand that it is impossible to build our way out of congestion. It is like loosening your belt to solve obesity.

But wait. There’s more.

Not only is the diverging diamond a boondoggle in the above mentioned ways. It also damages our world by adding more auto emissions into our air (by increasing per capita car trips) and reducing potential tax revenues in the region (by encouraging dispersed rather than compact land use patterns).

Future generations will shake their heads in disbelief over why our generation built these monstrosities.

There is one tiny upside to this overwhelmingly negative idea: it produces future jobs for people hired to remove these mistakes after we regain our senses.

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Filed under Bicycling, Sprawl, Suburbia, Transportation, Urban Design

The Undesirability of Autonomous Cars

By Dom Nozzi

December 16, 2016

Autonomous cars remind me of the many techno optimists in the 60s and 70s who assured us that we would soon be driving flying cars like The Jetsons.jetsons

So much faster! End of traffic jams! No air pollution!

Assuming autonomous cars become a significant part of our lives — which is highly unlikely given enormous difficulties associated with making autonomous vehicles work in the real world — such vehicles are likely to create a great many negative unintended consequences.

First, there will be a huge increase in per capita car travel due to the relative ease of car travel by such vehicles. Many trips that were formerly made by walking/biking/transit (or not at all) will now be by car — including by kids, the handicapped, and seniors who are now unable to drive.

Second, there will be a need for wider roads to handle that per capita increase.

Third, we will see higher average car speeds.

Fourth, we will see more pedestrians and cyclists killed by cars since the software will direct the car to kill such people rather than the driver.

Fifth, there will be a big increase in obesity due to the increased amount of travel by car.

And finally, we will suffer from a perpetuation of unsustainable transport energy consumption, toxic air emissions, and dispersed land use patterns.

uber-carOverall, like standard cars, autonomous cars are extremely toxic to cities. To be healthy, cities require slow speeds (which promote the agglomeration economies that cities require). Higher speeds induce more low-density dispersal, which destroys city health and the essential need for social capital. Cars isolate us, yet our genes and our cities need interaction.

In general, autonomous cars are a solution looking for a problem.

Given the consequences I mention above, we need to hope that autonomous cars are as “successful” as George Jetson’s flying cars. I’m not worried because I am confident autonomous cars will soon be forgotten.

What bothers me most is that such pie-in-the-sky vehicles distract us from pressing city and human needs we have neglected and failed to address for several decades.

How much progress have we made on passenger rail design and implementation, for example?

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Filed under Transportation, Urban Design

Promoting Traffic Safety

 

By Dom Nozzi

August 20, 2016

After three years of trying, I have finally been given the opportunity to give a presentation to the Boulder transportation advisory board – of which I have been a member. The topic will be on traffic safety, and I will be making the presentation in either early September or early October.

I decided one point I’d like to make is that if anything, streets have become much less safe than they were in the past – despite decades of often aggressive, extensive, expensive boulder-traffic-safetysafety efforts. This morning, I looked for a chart showing the trend in the number of annual deaths on US roadways. I have included a few charts from Wikipedia in this blog. “Annual Traffic Deaths” shows the crazy high number of annual deaths.

But the “Annual Deaths Per Mile Driven” chart shows that we are making a lot of progress on safety! I was surprised and realized I’d have to revise my presentation.

Then I came across a “Traffic Deaths” essay.

I learned from the essay that several decades ago, the auto folks needed to find a way to address the great alarm on the part of many Americans when they saw the huge number of traffic deaths. The solution to this PR problem – to head off serious efforts to reduce car dependence in our society – was to convey deaths based on MILES DRIVEN. It turns out that applying “miles driven” as a way to measure deaths is quite misleading. After all, if we used miles traveled, the space shuttle would be the “safest” way to travel…

Using that metric, the auto folks were able to reduce alarm (and meaningful efforts to reduce car dependence), because the metric shows improving traffic safety. Now we can sidestep the thought that 30,000 to 40,000 traffic deaths per year is barbaric (and demands our society reduce car use) and instead focus safety on individual motorist mistakes or mechanical solutions (which does almost nothing to correct this shocking, unacceptable road carnage problem).

One of my points about traffic safety is that our forgiving roadway design induces dangerous and growing levels of inattentive driving and excessive speeding. I believe inattentive driving and speeding are epidemic mostly because of our decades of employing forgiving roadway design. But if this is true, why does the chart show a decline in deaths since 1970?

My explanation is that while roads ARE more dangerous today than in the past, much of the reduction in deaths is associated with making cars (and, therefore, the motorists bike-car-crash1inside them) safer with such things as seat belts, air bags, and aggressive efforts against drunk driving – not to mention our removing a lot of trees and other “hazards” from near the side of roads.

I found another chart that shows a big increase in bicyclist deaths since the 1970s. That can partly be explained, I guess, by the growth in cycling since then, but I think it is also compatible with my belief that roads are more dangerous today. Motorists are safer in certain ways, but the growth in inattentiveness and speeding are leading to motorists killing more people bicycling.

In sum, it is clear to me that our roads need to be substantially redesigned to obligate slower, more attentive driving by motorists through various traffic calming, as well as reductions in the size of roadways and intersections. More warning signs, warning lights, warning paint, warning education, and warning enforcement has utterly failed to make our streets safe.

It is way past time to get serious and redesign our appallingly dangerous roadway system.

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The Perversity of American Subsidies

by Dom Nozzi

It is perverse that the US government so heavily subsidizes and provides for a form of travel (car travel) that is largely or fully responsible for…

About 45,000 deaths (not to mention the injuries) per year

The destruction and abandonment of so many US town centers and their quality of life 

The bankrupting of households and all levels of government

Suburban sprawl

The obesity epidemic and associated health problems

Enormous dependence on foreign oil produced mostly by nations that dislike the US

The gigantic and on-going loss of important wildlife habitat

The loss of peace and quiet

The huge loss of human interaction with their fellow citizens (we have become a nation of loners)

The loss of civic pride as a result of the homogenizing, strip commercial transformation of our communities

The diminishing returns that promotion of car travel now provides

The loss of small, locally-owned businesses

This is a recipe for societal dysfunction.

I believe so few of us are pointing out this elephant in the bedroom at least in part because we believe, mostly accurately, that our lives are impossible without cars, so we put ourselves in a gigantic state of denial with this Faustian Bargain.

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Visit my urban design website read more about what I have to say on those topics. You can also schedule me to give a speech in your community about transportation and congestion, land use development and sprawl, and improving quality of life.

Visit: www.walkablestreets.wordpress.com

Or email me at: dom[AT]walkablestreets.com

50 Years Memoir CoverMy memoir can be purchased here: Paperback = http://goo.gl/9S2Uab Hardcover =  http://goo.gl/S5ldyF

My book, The Car is the Enemy of the City (WalkableStreets, 2010), can be purchased here: http://www.lulu.com/product/paperback/the-car-is-the-enemy-of-the-city/10905607Car is the Enemy book cover

My book, Road to Ruin, can be purchased here:

http://www.amazon.com/Road-Ruin-Introduction-Sprawl-Cure/dp/0275981290

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On the Importance of Ratcheting Down Size and Speed

speedingcarhittingchild

By Dom Nozzi

Dangerous, high-speed, reckless, inattentive driving is now of epidemic proportions in nearly every community in America. Motor vehicle collisions with bicyclists and pedestrians (and with other motor vehicles) have remained at unacceptably high levels for several decades. The hostile, high-decibel conditions emitted by high motor vehicle speeds on American roads has led to costly, growing efforts to “buffer” homes and businesses from these frenzied, perilous, increasingly wide suburban highways. Fortressing efforts such as berms, masonry walls, large building setbacks, thick vegetation, and grade separations have all been tried. Those houses and commercial establishments which are unable to tolerate these increasingly roaring raceways are being abandoned or relocated to outlying, sprawling locations. Much of this abandonment explains the widespread decline of American Main Streets in the 60s, 70s and 80s.

 The quandary is vividly clear: More and more, we are horrified to discover that high-speed motor vehicles are simply incompatible with a livable community for humans, despite all our efforts to separate ourselves from the growing speedways that are engulfing us.

 High-speed roads are not only inhospitable to houses and businesses. They also create a “barrier effect” in which it is increasingly difficult to use such roads for bicycling and walking (or even transit). Consequently, per capita motor vehicle trips grow in the community. In combination with the higher speeds, fuel consumption and air pollution rise significantly.speedingcar

 As an aside, it should be noted that perhaps the most important reason that high-speed roads discourage and endanger bicycle and pedestrian trips is the “speed differential” between motor vehicles and those bicycling or walking. When motor vehicles move at modest speeds of, say, 15 mph, the speed differential between vehicles, bicycles and pedestrians is relatively small. Motorists have more reaction time. Bicyclists and pedestrians feel more comfortable next to slower speed cars. Collisions with cars are more likely to result in survival.

 These super-fast highways are not only deadly for pedestrians and bicyclists. They also become death traps for crossing wildlife, as higher speeds lead to a dramatic growth in “road kills.”

 What are the origins of high-speed roads?

 Motor vehicles, by their nature, require an enormous amount of space. Indeed, a car takes up so much space that roads become congested with cars with only a modest number of cars on the road. Because roads become congested so quickly when the car is used for transportation, the advent of the car in the early part of the 20th Century soon led road planners to push for wider road lanes (from, say, 8 ft wide to 12 ft wide) and an increase in the number of travel lanes (from, say, 2 lanes to 4 lanes).

 The growth in the size of roads led to an inexorable, vicious cycle. Because an emphasis on expanding and promoting the car “habitat” (roads and parking lots) inevitably leads to a decline in the quality of the human “habitat” (neighborhoods and Main Streets), the early part of the 20th Century witnessed a growing desire to flee the increasingly congested, dirty, degraded in-town locations for the “greener pastures” of suburban life in peripheral locations.

 Most humans lead busy lives. They have what is known as a “travel time budget”, wherein there is a desire to maintain an equilibrium in the amount of time devoted each day to regular travel (such as the commute to work). Cross-culturally and throughout history, we have learned that this travel time budget, on average, is approximately 1.1 hours per day.

 The growing desire to escape the cities being degraded by aggressive, high-speed motor vehicle travel meant, primarily, that there was a pressing need to widen roads to enable a growing number of cars to travel at high speeds for greater distances (in order to maintain the 1.1-hour travel time). Unfortunately, this sets into motion a downwardly spiraling vicious cycle in which high-speed motor vehicles bring us toward increasingly degraded cities, which pushes a growing number of us to flee to peripheral locations. The growth in peripheral residences leads to a growing popular demand for bigger, faster roads.

And each time we build bigger, faster roads, we degrade that ring of city growth (by creating a congested, unpleasant car habitat), which pushes a growing number of us to flee to a even MORE peripheral location in a never-ending process.

In Fighting Traffic, Norton points out that at the turn of the 20th Century, motorists were originally seen as being fully responsible for car crashes, rather than pedestrians or bicyclists. But this quickly changed. Instead of motorists being vilified as “speed maniacs,” the new villain became the “jaywalker,” a derogatory term that assigned blame to pedestrians who were irresponsibly crossing streets in unexpected locations (as they had done throughout history). Unexpected, carefree walking had become an incompatible public safety threat in the age of high-speed car travel. It was essential that uncontrolled pedestrians not using their designated crosswalks be seen as irresponsibly unsafe and immoral.

 

So the paradigm shift managed to reshape our thinking. Cars and car speeds are not a problem. What was needed, instead of slowing cars, Norton points out, was to vigorously prosecute “reckless” motorists and be vigilant in urging pedestrians to be careful. Comprehensive public safety education campaigns must teach all of us (particularly children) to be careful near roads. And to insist that pedestrians (and playing children) be kept out of the way of cars by keeping them off roads—or at least confined to intersection crosswalks.

 

Thus, the “forgiving street” (what Norton calls the “foolproof street”) was born. Dominating street design for nearly 100 years, this paradigm strives to design streets not to be safe and convenient for all users (including bicyclists, pedestrians and transit users), but to keep all non-motorized travelers out of the way of freedom- (and speed) loving American motorists. Streets are to be designed for safe driving at high speeds. And because forgiving street designers assume we will always have reckless drivers, streets must be designed to forgive reckless, inattentive driving. Grade separated intersections are needed. As are pedestrian skywalks. Move street trees and buildings and pedestrians away from the street.

 

The ultimate result, after several decades of this new motorist speed paradigm, has been an annual roadway death rate that remains extremely high. High levels of speeding and inattentive driving. Streets that are designed and safely usable only by cars, instead of being Complete Streets accessible to all. Unimaginably high levels of car dependency, heavy and worsening congestion, plummeting quality of life, a near absence of pedestrians, bicyclists and transit users, endless suburban sprawl and strip commercial, and declining downtowns.

 

I’m certain Norton would agree with me that an essential task for safety and quality of life is to return our communities to a lower-speed environment. And this must largely be achieved not through laws against speeders or speed limit signs, but through the design of streets that effectively ratchets down urban travel speed via such tactics as human-scaled traffic calming—and Monderman’s “shared space” concept (what I like to call “attentive” streets). High-speed car traffic is simply incompatible with the human habitat.

 

To escape this downwardly spiraling community dispersal (driven by a declining quality of life), the path is clear.  

Slow down motor vehicle travel.

We are fortunate that while nearly all American adults now use a car for nearly every trip, it is not at all necessary for us to strive for the impossible, undesirable objective of “getting rid of all cars.” The good news is that we can keep our cars. But we need to become more the masters of our cars rather than their slaves. That means we need to design our communities and our roads to obligate motorists to be better behaved (primarily by driving at more modest speeds and doing so more attentively). When motor vehicle speeds decline, and motorists drive more attentively, we find that community quality of life can be maintained, and even improved, despite the presence of cars.

Another crucial aspect of “well-behaved” motor vehicles is to return to the tradition of building communities that provide travel choices, so that folks are not required to make all trips by motor vehicle. Creating travel choice means a return to the tradition of establishing “mixed use,” higher density neighborhoods. Homes are co-mingled with modest shops, offices, civic buildings, and pocket parks. This sort of traditional, mixed use neighborhood design substantially reduces trip distances, which means that walking, bicycling and transit use become more feasible and likely. The short distances and mixed uses also means that streets do not need to be over-sized with 11- or 12-foot wide travel lanes or 4- and 6-lane roads.

 And these factors contribute to a crucial, inevitable result: slower, more attentive motor vehicle travel (which leads to safer, more livable driving—and driving that is optional rather than required).

For most communities, design imperatives are therefore as follows:

First, neighborhood residential densities in community core areas need to be high enough to support a healthy, frequent transit service, and smaller, neighborhood-based retail shops. A general rule of thumb is that this density needs to be at least 6 to 8 dwelling units per acre (in general, the higher the density, the better). Higher-density, mixed use communities promote more modestly sized neighborhoods and communities.

Second, communities need to continue the nation-wide trend of installing traffic calming designs, and doing so throughout the community. Traffic calming has been found to deliver extremely cost-effective benefits to communities that employ them. Slower (“calmed”) cars means healthier, quieter neighborhoods that are particularly safer for children, seniors and pets. Air pollution declines. Walking and bicycling are encouraged (due, in part, to a reduced speed differential). Neighborhoods, therefore, with stable (or improving) property values.

 Preferably, calming is done by reducing horizontal dimensions rather than using vertical interventions. Desirable horizontal street modifications include reducing in the width of travel lanes, reducing the number of lanes (particularly important, and commonly known as road “dieting”), using landscaped or hardscaped sidewalk bulb-outs, using modest intersection turning radii, installing chicanes, restoring on-street parking, putting in roundabouts, and installing traffic circles. Each of these treatments can effectively reduce average motor vehicle speeds while still allowing for needed, higher-speed emergency response by fire trucks, police cars, and ambulances. Undesirable vertical treatments mostly include speed humps, which are commonly used due to low cost, but which can create significant problems for emergency vehicles.

 As I note above, it is important that a community seeking to slow average vehicle speeds do so throughout the community, to the extent possible.

 Over the course of the past several decades, American motorists have been given the opportunity to drive mostly on what are called “forgiving streets.” The forgiving street design was born in the minds of engineers who observed car collisions with trees, other cars, and bicyclists. The “solution” seemed obvious: Remove trees, parked cars, buildings and other “obstacles” from the shoulders of the street. Increase lane width. Add additional travel lanes.

 The theory was that such treatments would mean that incompetent, inattentive, higher-speed motorists would be “forgiven” if they, say, drove too fast or drove off the roadway, because there would be less “obstacles” to crash into.

 What they forgot about was human nature. Humans, by nature, tend to drive at the highest possible speed that can be driven safely. Traditionally, narrow streets with on-street parked cars, buildings pulled up to the street, and street trees meant that a street could only be driven safely at, say, 20 mph. Drivers needed to drive relatively slowly, courteously and attentively (read: carefully) to safely negotiate such streets.

But today, with the advent of the theory that forgiving street design increases safety, we now find ourselves, ironically, with less safe streets. Forgiving streets allow even inattentive, high-speed, reckless, low-skill drivers to drive safely at, say, 40 mph without crashing into “obstacles.” The unintended result is that we have an epidemic-like, artificially high number of motorists who drive too fast and recklessly because our street design encourages such driving.

 The result of the forgiving street paradigm should have been predictable. Less safe, higher-speed streets increasingly filled by motorists who are using cell phones or putting on make-up as they drive. And it should come as no surprise that the forgiving street is breeding an army of incompetent drivers, since they require less skill to drive than the traditional street.

 Conventional traffic engineers and elected officials were happy to learn that forgiving streets provided an additional “benefit.” Not only did we expect them to increase safety. They would also SPEED UP TRAFFIC. So support for the forgiving street was found from not only those seeking more road “safety,” but also those who live in and benefited from the construction of peripheral, sprawl housing (which is enabled by higher-speed roads).

 Because nearly all of our roads have now been built to be “forgiving,” the vast majority of American drivers now have the expectation of being able to drive at high speeds at all times. As a result, it is essential that we ratchet down these high speed expectations by incrementally calming our roads community-wide. Having only one or a handful of calmed roads in a community does not typically work well, as most drivers in such a community will retain the expectation of high-speed driving because only rarely (if ever) will such drivers be obligated to slow down. If the expectation of high-speed driving persists, the infrequent instances of calming can result in a significant level of “road rage” (and non-compliance) by motorists who believe they have an entitlement to driving 60 mph on community roads.

big-firetruck1 Finally, it is essential to recognize that there is a growing trend by citizens and fire departments to purchase increasingly large vehicles, and doing so creates enormous obstacles for a community striving to use the important designs called for above. Why? Because large vehicles—particularly large fire trucks—almost always prevents even an informed, well-meaning community from establishing the modest street design treatments needed for livability and safety. Large vehicles stand in the way of the use of modest travel lane widths, modest turning radii, and many effective traffic calming techniques.

 It is therefore essential that communities do what they can to control the growing size of fire trucks and other vehicles used in the community.

 In sum, the critical needs for community protection and improvement are to design communities and their streets to create modest motor vehicle speeds.

 And doing so is most effectively achieved by emphasizing a control in the size of motor vehicles, emergency vehicles, roads, and neighborhoods.

 

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Visit my urban design website read more about what I have to say on those topics. You can also schedule me to give a speech in your community about transportation and congestion, land use development and sprawl, and improving quality of life.

 

Visit: www.walkablestreets.wordpress.com

 

Or email me at: dom[AT]walkablestreets.com

 

50 Years Memoir CoverMy memoir can be purchased here: Paperback = http://goo.gl/9S2Uab Hardcover =  http://goo.gl/S5ldyF

 

My book, The Car is the Enemy of the City (WalkableStreets, 2010), can be purchased here: http://www.lulu.com/product/paperback/the-car-is-the-enemy-of-the-city/10905607Car is the Enemy book cover

 

My book, Road to Ruin, can be purchased here:

 

http://www.amazon.com/Road-Ruin-Introduction-Sprawl-Cure/dp/0275981290

 

My Adventures blog

 

http://domnozziadventures.wordpress.com/

 

Run for Your Life! Dom’s Dangerous Opinions blog

 

http://domdangerous.wordpress.com/

 

My Town & Transportation Planning website

 

http://walkablestreets.wordpress.com/

 

My Plan B blog

 

https://domz60.wordpress.com/

 

My Facebook profile

 

http://www.facebook.com/dom.nozzi

 

My YouTube video library

 

http://www.youtube.com/user/dnozzi

 

My Picasa Photo library

 

https://picasaweb.google.com/105049746337657914534

 

My Author spotlight

 

http://www.lulu.com/spotlight/domatwalkablestreetsdotcom

 

 

 

 

 

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