Tag Archives: air emissions

Protecting “Neighborhood Character” through NIMBYism?

By Dom Nozzi

October 15, 2017

There are people in Boulder who regularly state that the City Council has turned a blind eye/ear to neighborhood concerns. That they are not concerned about “protecting neighborhood character” (which is a transparent euphemism for NIMBYism) in their allegedly corrupt rush as Council members to ruin Boulder with rapid, uncontrolled growth.nimby-web-2

The NIMBYs also make the bizarre claim that this “out of control” Council will lead to environmental degradation and loss of affordable housing.

But I utterly fail to see how the positions of the NIMBY people will achieve these worthy objectives if, as is clear to anyone paying attention, their positions result in a big jump in car travel and a perpetuation of rapidly rising housing costs.

If you oppose, as nearly all of these NIMBYs do:

Smaller homes

ADUs

Co-ops

Smaller lot sizes

Smaller setbacks

More neighborhood mixed use

Less parking (and the conversion of existing parking to housing)

More density

Priced parking

Buildings over one or two stories

Road diets

…you are thereby calling for more per capita car trips, more carbon/air emissions, much higher housing costs, a continuation of neighborhood character being changed by the in-migration of much more wealthy residents, and sprawl into outlying towns.

Oops.

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Filed under Politics, Transportation, Urban Design

Reducing Car Trips in Boulder

By Dom Nozzi

July 25, 2017

Way back in 1989, Peter Newman and Jeffrey Kenworthy showed that traffic congestion REDUCES air emissions and gas consumption at the regional level. This is in part due to the reduction in low-value car trips caused by the time tax that congestion imposes.

The compact development pattern that can result from more housing being built in Boulder would reduce the PER CAPITA trips made by car. Since Boulder currently has very low-density, dispersed patterns of development (and WAY too much free parking), per capita car trips are very high.large lot subdivision

Boulder is way better off — and is much more affordable and equitable — if the City successfully encourages more compact development patterns through the construction of more housing.

It would mean a lot more Boulder residents can choose to travel by walking, bicycling, or transit.

Environmental quality goes way up when per capita car trips go down. And Boulder will be a much friendlier and happier and healthier place, as healthier, more enjoyable, sociable interaction is much more likely when using transit, when walking, or when bicycling.

Boulder has made a huge tactical error over the past several decades by thinking that minimizing population growth and reducing density was the way to reduce car trips. Instead, that tactic has put too many Boulder residents in cars, made it much more difficult to travel without a car, and has made Boulder a lot less affordable.

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California legislation aims to reduce sprawl: Watch Out for Unintended Consequences

 

By Dom Nozzi

November 2007

In the fall of 2007, a member of the new urbanist email list I was subscribing to posted the following news: “CA bill to tie transportation funding to reducing sprawl”

“Enter state Sen. Darrell Steinberg, D-Sacramento, who has written a bill that would reward land-use planning that reduces sprawl. Specifically, it would require the California Air Resources Board to set greenhouse gas targets for metropolitan areas. Then regional agencies would have to devise growth and transportation plans to meet those targets. And future transportation funding would be tied to meeting those targets.”

My response was to state that I certainly hoped this bill was properly crafted to avoid what I fear can be a tragic unintended consequence.

Over the years, I’ve regularly heard the sprawl lobby claim that road widenings are needed on congested roads to reduce air pollution and gas consumption. To a great many people — including some environmentalists — the argument makes sense. “Widening a congested road creates more free-flowing traffic, which means less gridlock, which means less pollution and gas consumption due to a reduction in idling cars.”

Of course, some of us now recognize that widening roads usually does the reverse, because Carmageddon highwaywidening typically induces more car trips (i.e., an increase in pollution and gas consumption) and a quick return to congestion — not to mention an inducement to more sprawl.

My fear, therefore, is that the bill will actually create a new justification in CA for more road widening (and more sprawl) as a way to “reduce” greenhouse gases.

Does the bill specifically state that road widening is not an allowable greenhouse gas reduction tactic?

I hope so.

 

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Promoting Free Flowing Traffic is a Bad Idea for Boulder Colorado

 

By Dom Nozzi

August 16, 2013

Despite its reputation, Boulder CO is a long way away from where it needs to be on an over-arching position on transportation and land use. In particular, I remain deeply concerned that City policy is that it is essential to promote free-flowing car travel (by adding turn lanes, generally opposing road diets, establishing continuous left-turn lanes, synchronizing traffic signals for cars, etc.) in order to reduce emissions and fuel use.

By striking contrast, I am of the opposite view.

I am firmly convinced of two things on this issue:

Car travel is a zero-sum game. Nearly always, when car travel is made more convenient or free-flowing (usually by giving cars more space), bicycling, walking and transit decline (due to “barrier effect” problems). Promoting free-flowing traffic shifts many trips from non-car travel to car travel as a result.

Low-value car trips. When roads and nearly all car parking is free, we are begging people to drive a car with those big subsidies. After all, there are so many rational reasons to drive a car: cargo carrying, convenience, security, speed, status, flexibility, protection from weather, etc.). Since motoring appears to be “free” when roads and parking are free, there are little if any disincentives to driving. First-year economists know quite well what the inevitable result will be: Over-use of roads and parking due to the INDUCEMENT of new car trips (particularly “low-value” trips such as driving a car to rent a video at rush hour) that were formerly discouraged from happening at rush hour or on certain roads. In other words, if a road in Boulder is carrying, say, 20,000 vehicles per day, and the City or State opts to make the road more free-flowing, that road will NOT continue to carry 20,000 ADT. It will now carry, say, 25,000. The 5,000 new (latent, induced) trips were formerly discouraged by the less free-flowing conditions in the past.

An example of latent demand: I hear friends say over and over again that they are not going to drive at such and such a time or on such and such a road because those times or roads are too crowded with cars. It does not take rocket science to know what will happen if we make those times or roads more free-flowing…

The combination of the above two factors therefore means that free-flowing cars produce MORE car emissions and gasoline consumption, not less (as the advocates of free-flowing traffic would have us believe). Yes, in free-flow conditions, an INDIVIDUAL CAR produces less emissions and uses less fuel, but on a community-wide basis, the induced new trips result in more emissions and fuel use overall. In 30th-and-arapahoe-double-leftseffect, engineers in this case fail to understand simple economics and changes in human behavior (economics and psychology, again) when they strive for free-flowing conditions. They fail, in other words, to realize that free-flow induces new car trips that would not have occurred had the free-flow conditions not been promoted. This inducement, again, is inevitable when we have free-to-use roads and (mostly) free parking. Largely because there is a great deal of latent demand for more car travel if conditions are made more convenient or pleasant for car travel.

By the way, the concept of induced car travel has been quite well-established for a number of decades. A great many traffic engineers know it exists. But almost no conventional traffic engineer will act on their awareness of induced demand – probably because they have not been given permission to do so.

The above also illustrates why, even in theory, it is impossible to build (widen) our way out of congestion. Induced demand for car trips is the bugaboo elephant in the bedroom that Boulder seems to be ignoring.

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Filed under Road Diet, Sprawl, Suburbia, Transportation

Free-Flowing Traffic Tends to Increase Emissions and Fuel Consumption

 

By Dom Nozzi

August 15, 2013

Most American cities are a long way away from where they need to be on an over-arching position on transportation and land use. In particular, it is a nearly universal belief that it is essential to promote free-flowing car travel (by adding turn lanes, generally opposing road diets, establishing continuous left-turn lanes, synchronizing traffic signals for cars, etc.) in order to reduce emissions and fuel use. By striking contrast, I am of the opposite view. I am firmly convinced of two things on this issue:

  1. Car travel is a zero-sum game. Nearly always, when car travel is made more convenient or free-flowing (usually by giving cars more space), bicycling, walking and transit decline (due to “barrier effect” problems). Promoting free-flowing traffic shifts many trips from non-car travel to car travel as a result.
  1. Low-value car trips. When roads and nearly all car parking is free, we are begging people to drive a car with those big subsidies. After all, there are so many rational reasons to drive a car: cargo carrying, convenience, security, speed, status, flexibility, protection from weather, etc.). Since motoring appears to be “free” when roads and parking are free, there are little if any disincentives to driving. First-year economists know quite well what the inevitable result will be: Over-use of roads and parking due to the INDUCEMENT of new car trips (particularly “low-value” trips such as driving a car to rent a video at rush hour) that were formerly discouraged from happening at rush hour or on certain roads. In other words, if a road is carrying, say, 20,000 vehicles per day, and the City or State opts to make the road more free-flowing, that road will NOT continue to carry 20,000 ADT. It will now carry, say, 25,000. The 5,000 new (latent, induced) trips were formerly discouraged by the less free-flowing conditions in the past.

An example of latent demand: I hear friends say over and over again that they are not going to drive at such and such a time or on such and such a road because those times or roads are too crowded with cars. It does not take rocket science to know what will happen if we make those times or roads more free-flowing…

The combination of the above two factors therefore means that free-flowing cars produce MORE car emissions and gasoline consumption, not less (as the advocates of free-flowing traffic would have us believe). Yes, in free-flow conditions, an 1158INDIVIDUAL CAR produces less emissions and uses less fuel, but on a community-wide basis, the induced new trips result in more emissions and fuel use overall. In effect, engineers in this case fail to understand simple economics and changes in human behavior (economics and psychology, again) when they strive for free-flowing conditions. They fail, in other words, to realize that free-flow induces new car trips that would not have occurred had the free-flow conditions not been promoted. This inducement, again, is inevitable when we have free-to-use roads and (mostly) free parking. Largely because there is a great deal of latent demand for more car travel if conditions are made more convenient or pleasant for car travel.

By the way, the concept of induced car travel has been quite well-established for a number of decades. A great many traffic engineers know it exists. But almost no conventional traffic engineer will act on their awareness of induced demand – probably because they have not been given permission to do so.

The above also illustrates why, even in theory, it is impossible to build (widen) our way out of congestion. Induced demand for car trips is the bugaboo elephant in the bedroom that nearly all American cities ignore.

 

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Urbanism is the New Green

By Dom Nozzi

With less compact, lower-density, suburban development, extremely high per capita car use is inevitable, and high levels of walking, bicycling and transit is impossible.

With more compact, higher-density, urban development, car use is relatively inconvenient and costly (which substantially reduces car travel), and walking, bicycling and transit is much more convenient, safe & enjoyable (which dramatically increases such travel).Catania Italy walkable

Both Boulder CO (where I now live) and Gainesville FL (where I toiled for 20 years as a long-range city planner) have exceptionally low, unsustainable suburban densities, which makes extremely high per capita car travel a locked in certainty. In both cities, per capita air emissions are shamefully VERY high due to low-density-induced car dependence.

Boulder has fooled itself into thinking it can achieve high levels of walking, bicycling and transit use simply by leveraging its wealth to build lots of sidewalks, bike paths and bus service. Nevertheless, very high car use remains (as illustrated quite well by the extreme rage directed against the Folsom right-sizing project in 2015).

The only effective way to induce high levels of walking, bicycling and transit use is to take away speed, space, and subsidies from cars (the fourth essential “S” is to Shorten travel distances via compact, mixed use development). Cars need to be slowed down (particularly in town centers) with traffic calming street design. Oversized streets and parking lots (which are found over and over again in all American cities) need to be shrunk down to sustainable, human-scaled size. Huge motorist subsidies have persisted for nearly a century, and must be reduced. Giant subsidies are found in abundant free parking and city requirements that new development provide parking; untolled roads, which bicyclists, pedestrians and transit users pay for – not just motorists; and unpriced gasoline and too-low gas taxes (there are many other subsidies, by the way).

Boulder and Gainesville have almost no development that is compact & mixed use, which make both cities rather unsustainable and extremely car dependent.

Worldwide, studies have found that lower-density, less compact cities emit extremely high levels per capita of toxic air emissions due mostly to extreme car dependence. Conversely, more compact, higher-density cities emit extremely low per capita levels of air emissions due mostly to low car dependence. Shame on Boulder for the several decades of maintaining a political consensus that compact (more dense) development is bad.

There is an emerging consensus (outside of Boulder) that density (urbanism) is the New Green.

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

What’s with the Double Standard on Right-Sizing a Road?

By Dom Nozzi

Over the past several weeks, there has been an avalanche of letters attacking the City proposal to right-size Folsom. Hundreds of opponents filled the Council auditorium to denounce the idea at multiple meetings. The complaints have been repetitive: There are no metrics telling us whether the projects have succeeded or not! Not enough involvement by stakeholders such as businesses and neighborhoods! Not enough public involvement! No studies showing whether they will work! It will cause terrible congestion and air pollution! No before and after studies! Pro-bike bias! Waste of a huge Folsom-N.-rendering_web-400x267amount of money!

First of all, citizens should know that City staff has done many studies and public meetings that are alleged to be lacking. Far more than most other transportation projects conducted in the past.

Second and much more importantly, I am utterly shocked by the double standard here. I have been working professionally and academically in transportation for over 30 years, and I have never seen this level of enraged opposition, calls for studies, and requests for more public input. One would think that the City was proposing to bring about the end of the world.

The double standard is that I don’t recall ANY opposition when the City has proposed to install a second left-turn lane at an intersection (which has been done several times in Boulder), among many other pro-car projects. No calls for studies. No demands that stakeholders be involved. No metrics telling us if the double-left had the intended benefits a year later. No before and after studies. No cries that it will increase air pollution or car dependence. No demands that the double-left turn be tested first before it is made permanent. No whining that the double-left turn is a big waste of money (for the record, double-left turns cost a lot more money, generally, than right-sizing).

Few people, if any, attend meetings to oppose such an enormous expansion of an intersection.

I would think that the outcry from a proposed double-left would be furious. After all, double-left turns increase air pollution, car trips, local taxes, regional car trips, car crashes, speeding, inattentiveness, injuries and deaths. They reduce walking trips, biking trips, and transit trips (because the intersection is now much more dangerous to walk through or bicycle through). They are toxic to businesses and homes near the intersection.

double left turn lane intersection boulderBy striking contrast, national studies show that right-sizing reduces air pollution, speeding, inattentiveness, car trips, car crashes, injuries and deaths. They increase walking trips, biking trips, and transit trips. They improve the health of retail and residences (I understand that many businesses in Seattle now ask that their street be right-sized after they have seen their competitors benefit after their streets were right-sized).

Yet in Boulder, we see furious opposition to right-sizing and hardly any objection to a proposed double-left turn. And by the way, unlike right-sizing, double-left turns are NEVER tested first to see if they will work. They are just “rammed down our throats,” as many right-sizing opponents oddly tell us about right-sizing.

Making a road change that eases bicycling and walking is met with fury. Making a road change that eases driving (and discourages bicycling and walking) is met with silence.

Given this, one would think that there is a very pro-CAR bias in Boulder. One also has to ask: Who needs enemies when we have ourselves?

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Right-Sizing a Road is Right for Boulder

By Dom Nozzi

Boulder proposes to right-size a portion of four streets starting in the summer of 2015: Folsom, Iris, 55th and 63rd.

Right-sizing a road involves repurposing road travel lanes from car-only travel to other uses such as bicycle lanes or on-street parking. Right-sizing happens on streets that are deemed to be inefficiently and unsafely oversized. Oversized streets tend to create many negative impacts, such as cars traveling at excessive, dangerous speeds. Right-sizing creates “Complete Streets” that can be used for all forms of travel – bicycling, walking, transit, and motor vehicle travel.Road-Diet

Many fear that right-sizing a road will result in unacceptable changes. Here are reasons why fears tend to be unfounded, as well as the many benefits of right-sizing:

  • An enormous number of right-sizing projects have been immensely successful throughout the nation – including in cities that are rapidly growing.
  • Despite the conventional wisdom, providing things like adding bike lanes, building new sidewalks, or improving bus service are not effective ways to effectively encourage more bicycling, walking, or transit use. The key is to reduce the space allocated to motorists, reduce the speed of motorists, reduce subsidies allocated to motorists, and shorten distances to destinations. Right-sizing achieves two of those, which makes the tactic a powerful tool to grow the number of active travelers.
  • Boulder has previously right-sized portions of Baseline, Table Mesa, 13th Street, and North Broadway (Pearl Street downtown was actually closed to traffic to create Pearl Street Mall). In each case, there was very vocal opposition. Nevertheless, the fears expressed did not materialize, and a large jump in bicycling and walking was the result. This tracks national experience, where hundreds of right-sizing projects have succeeded. In nearly all such cases, large majorities opposed the proposal, which was followed by large majorities supporting the right-sizing AFTER they were installed.
  • Opponents of right-sizing tend to throw around alarmist, hysterical, misleading, end-of-the-world comments about right-sizing. That the community proposes to prohibit car travel. Or force everyone to ride a bicycle. But there is an enormous difference between creating a modest delay in car travel versus prohibiting car travel. Indeed, the tactic is much more accurately described as a way to NUDGE people toward more desirable ways of traveling, rather than FORCING them to give up their car.
  • Due to excessive speeds or insufficient space for bicycling, the four candidate roads discriminate against bicycle travel, walking, and transit users. Right-sizing therefore creates more equity. More transportation choice. Roads that are car-only are toxic to communities.
  • Peter Swift conducted a study in Longmont CO that found that efforts to reduce fire truck response times by increasing roadway dimensions INCREASED the overall number of injuries and deaths in a community because the number of injuries and deaths associated with fires is tiny compared to the large increase in injuries and deaths caused by high speed car travel. By increasing car speeds through excessive road sizes, public safety declines. Fire safety is a subset of life safety. To reduce overall injuries and deaths in a community, therefore, suboptimizing on fire safety by speeding fire trucks is counterproductive. On the four candidate roads, there have been 419 car crashes over the past three years. This is far, far lower than the number of fires near these roads over that time period. Right-sizing therefore is a big win for reducing injuries and deaths. As an aside, it should be noted that the Boulder Fire Department is not concerned about the proposed right-sizing, largely because of the installation of a center turn lane.
  • Right-sizing tends to be beneficial not only to bicyclists, pedestrians, and transit users. It is also beneficial to small retailers, residential homes, and overall community quality of life.
  • There tends to be very little loss of road capacity when a road is right-sized. This is particularly true when a road is right-sized from four lanes to three, because the inside lanes of a four-lane street frequently are serving as left-turn lanes. When a car makes a left turn on a road without a turn-lane at an intersection, the road is essentially already functioning as a three-lane road. In addition, right-sizing reduces average car speeds. When cars are moving at slower speeds, they tend to travel closer to other cars on the street, because less stopping or slowing time is needed at lower speeds. When cars are closer together, the road lane is able to handle a larger volume of cars. Road lanes with faster car travel are able to handle smaller volumes of cars.
  • Models used by traffic engineers tend to be unable to take into account “induced” car trips and “discouraged” car trips. Induced car trips are those trips that would not have occurred had the community not previously over-sized a road (or because the motorist is not obligated to pay a fee to use the road). Discouraged car trips are those trips that are relatively flexible. When a road becomes slower, some trips shift to non-rush hour times, or happen on alternative routes. Because traffic models – which engineers use to predict traffic volumes and congestion due to various road configurations – don’t do well in incorporating induced or discouraged trips, such models tend to exaggerate problems such as congestion. In the real world, then, problems associated with right-sizing are much less significant than predicted by engineering models.
  • Commonly, when a right-sizing project is proposed, there are fears of “spillover” traffic on parallel routes. This fear tends to be vastly overblown due to the issues described above. A great many trips on streets are discretionary in the sense that they can happen at non-rush hour times, on alternate routes, or not at all. In other words, not all car trips are emergency trips or otherwise essential trips that must be made on that route at that time. This is a very common misconception, and creates “worst case scenario” thinking that is unsustainable .
  • Right-sizing results in a significant increase in road safety. This is due to lower average car speeds, more attentive driving, and the inability of motorists to weave from lane to lane as they attempt to pass other cars. When there are multiple travel lanes in the same direction, the fastest car sets the pace. Safer roads invite and dramatically increase the use of the road by bicyclists, pedestrians, and transit users.
  • Commonly, there is a fear that a right-sized road will make it more difficult to enter the road from a side street (due to cars being closer together). In fact, right-sized roads often make entering easier. This is because the entering motorist needs to cross less travel lanes when making a left turn onto the right-sized road (and wait in the left-turn lane if there is not an opening). In addition, slower car speeds on a right-sized road makes it easier to enter the right-sized road, because smaller gaps are needed to safely enter.
  • Motorists are understandably often inconvenienced or annoyed by “flashing light” mid-block crossings for pedestrians. Because right-sizing reduces crossing distances and car speeds, such annoying crossing treatments are less necessary and therefore less used.
  • It is common for opponents of right-sizing to claim that increased congestion from right-sizing will increase air emissions and fuel consumption. In fact, the reverse tends to be the case, because right-sizing commonly discourages trips – particularly “low value” trips such as a trip to get a cup of coffee at rush hour. To the claim that this is an unacceptable form of “social engineering,” it should be pointed out that the massive subsidies provided for the car-dependent suburban lifestyle is the most substantial form of “social engineering” in world history. Right-sizing nudges society towards a more efficient, natural state of affairs.
  • Overall quality of life increases for neighborhoods near right-sized roads, such as reduced air emissions, reduced noise pollution, less regional car trips impacting the neighborhood, and more safety.
  • For the first time in history, vehicle miles traveled (VMT) is leveling off and starting to decline. This trend, which many believe is long-term, means that fears of excessive congestion due to right-sizing should be lower.
  • Right-sizing increases travel by bicyclists, pedestrians, and transit users. It reduces noise pollution, air emissions, speeding, and fuel consumption. It improves conditions for homes and retailers near the right-sized road. Right-sizing reduces the number or injuries and deaths on the road. It provides more space for landscaping, on-street parking, bicycle and pedestrian facilities, and stormwater management. Right-sizing reduces maintenance costs. All of these benefits improve the quality of life for those near the corridor and community-wide.

The question of trade-offs must be asked: Is the loss* of, say, 30 seconds of your travel time more valuable than reduced injuries and deaths, the reduced air emissions, the increase in bicycle, pedestrian and transit travel, the reduced noise pollution, the improved visual quality, the improved conditions for homes and retailers, the reduced speeding, and the lower cost for local government?

For nearly all of us, I don’t think so.

I think the case is clear that the many large benefits of right-sizing far outweigh the relatively minor increase in travel time. The success and popularity of right-sizing throughout the nation demonstrates this quite well.

* Note that right-sizing does not necessarily result in a loss of any travel time at all. For example, some motorists respond to right-sizing by avoiding rush-hour travel or opt for alternative routes.

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The Folly of Double-Left Turn Lanes

There is a troubling, counterproductive “solution” that continues to be employed for addressing congested intersections – even in communities that are otherwise progressively promoting transportation choice. The “solution” is to add a second left turn lane to an existing left-turn lane when there is a perception that the number of motorists waiting in the single left-turn lane has grown too large.

Conventional traffic engineering claims that creating a double-left turn lane at an intersection is an double left turn lane intersection boulder“improvement” that will reduce greenhouse gas emissions by reducing congestion. And that a double left turn does not conflict with the transportation plan objective of promoting pedestrian trips.

On the contrary, I believe that double-left turn lanes will INCREASE emissions and will REDUCE pedestrian trips.

Double left-turn lanes cause serious problems for scale and safety for bicyclists and pedestrians, but have been shown to be counterproductive even if we are just looking at car capacity at an intersection. Adding a second left turn lane suffers significantly from diminishing returns. That a double-left turn does NOT double the left turn capacity – largely because by significantly increasing the crosswalk distance, the walk cycle must be so long that intersection capacity/efficiency (for cars) is dramatically reduced.

Cities across the nation are facing severe transportation funding shortfalls, yet at the same time, they are often building expensive and counterproductive double-left turn lanes.

Why? Probably because of the absurdity that transportation capital improvement dollars are in a separate silo than maintenance dollars, and that the former dollars are mostly paid by federal and state grants.  Of course, double-left turn lanes also destroy human scale and obliterates the ability to create a sense of place, but those are much more difficult arguments to make.

A colleague of mine adds that double-left turn lanes are an abomination. He adds that “they are a sign of failure: failure to provide enough street connectivity, so that when drivers do come to an intersection, it is gigantic, so it can accommodate all the left turns that had not been allowed prior to that point. Many trips on extra wide arterials are very short, and involve three left turns: one left turn onto the arterial and one left turn off the arterial: there trips could and should be made on connected local streets.”

How can a city claim it is short on transportation funding when it is building such counterproductive facilities? Double-left turn lanes…

  • Increase per capita car travel and reduce bike/pedestrian/transit trips.
  • Increase GHG emissions and fuel consumption.
  • Induce new car trips that were formerly discouraged (via the “triple convergence”).
  • Promote sprawling, dispersed development.
  • Discourage residential and smaller, locally-owned retail.

Cities need to draw a line in the sand: Place a moratorium on intersection double-left turn lanes and eventually removal of such configurations. Double-lefts are too big for the human habitat. They create a car-only atmosphere.

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Curbing the Expectation of Driving at High Speeds

By Dom Nozzi

Many of us who seek to make our world more conducive to happy people rather than happy cars are adamant about the importance of slowing car speeds in communities.

Residential streets typically do not promote the problem of high-speed, free-flowing traffic, but sometimes they do act in such a way when they are used for “cut-through” trips or if they are relatively large neighborhood streets which “collect” traffic fed from smaller streets in the neighborhood (usually called “collector” streets).

Lowering the average motorist speed is one of the most essential ways I can think of to improve quality of life. And the most effective way to do that is through calming strategies which design the street to force slow car travel. It is critical that we LOWER THE EXPECTATION of motorists to be driving at high speeds. High speed car travel in a community should not be considered the “default” way for a motorist to travel.

Tragically, conventional traffic engineers have designed our streets for the past 100 years to promote high-speed travel – even on what should be quiet, low-speed streets. The result is that too many motorists now believe that relatively high-speed driving is the norm.

If we instead start designing our communities so that, eventually, most streets in a community are designed for slow car travel, general expectations will evolve so that a motorist realizes that the normal manner of driving is to drive slow (except on interstate highways, of course). With such an expectation, there will be significantly less road rage (and related hostile driving) in calmed areas, because the motorist EXPECTS to drive slow.

Designing streets for slow speeds is particularly important on residential streets, because such streets are the places where we most expect children and seniors to be, and where people are in homes and bothered by the noise of high-speed car travel. We also need to slow cars on the BIG roads in our community to ensure we solidify a general motorist expectation that they are driving in a slow speed community.

“Road rage” and fast driving are NOT genetically programmed into humans. A slow-speed community is NOT unrealistic.

In a discussion about slower car speeds, it is important to note that speed limit signs have little or no impact on how fast a motorist drives. Average driving speed on a street is dictated by the “design speed” of the street. The conventional traffic engineering philosophy is to assume that safety is best achieved by designing the “forgiving” street. That is, to design the street so that the motorist is “forgiven” if they, say, drive too fast and lose control of their car.

What this means is that the street is made wide and obstructions are kept away from the shoulders so that a fast, out-of-control motorist will not smash into anything.

Unfortunately, this fails to take into account the motorist psychology. If you design a street for safe driving at 40 mph, the average motorist will drive 40 mph, even if the posted speed limit signs say 30 mph, because average driving speed is determined by the maximum speed a motorist feels comfortable driving.

Typically, this philosophy means that a street with a speed limit of 30 mph has been designed with a “design speed” of 40 mph. We should not be surprised when a large number of motorists drive 40 mph on such streets. Enforcement is nearly impossible, short of a police state.

Therefore, in my opinion, the “forgiving street” philosophy gives us LESS safety due to higher speed (and more inattentive) driving.

The effective solution for slowing cars is to “retrofit” our streets (including residential streets) with calming designs that force cars to slow down (which is why things like speed humps are often called “sleeping policemen”).

However, “vertical” treatments like humps are almost never, if ever, appropriate for streets (including residential streets) – particularly those that are on designated emergency vehicle routes (where calming needs to be carefully designed to not excessively impede such vehicles).

In the case of such routes, “horizontal” calming is usually called for. Horizontal treatments include such things as curb extensions or other forms of street narrowing, as opposed to “vertical” calming like humps.

Does Traffic Calming Increase Air Pollution?

A common objection to traffic calming is that air emissions will increase due to “stop and go” traffic that is induced by calming. But this concern makes the mistake of  being overly reductionist. Peter Newman and Jeffrey Kenworthy effectively point out why reductionism in this case leads to erroneous conclusions. Newman and Kenworthy correctly point out that those who fear higher emissions due to calming forget about changes in motorist behavior that occur with calming. Reductionist thinking in this case only looks at what is coming out of a tailpipe of individual cars.

But Newman and Kenworthy, take a broader and more accurate view by pointing out that changes in travel behavior (caused by higher development densities, shorter travel distances, congestion, calming, etc.) completely swamp any air pollution gains that can be realized from individual cars that have less stop-and-go travel.

I will grant that it is possible there will be “micro-level” increases in air pollution levels due to calming. But at the “macro” (community) level, I’m convinced there is a net reduction in air pollution. That is, there is LESS air pollution at the community level.

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