Repost: More Motorized Traffic Is Bad; Traffic Congestion is Good

Public health and climate mitigation are more important than mobility

Other posts on transportation policy:

“Urban Freeway” is an Oxymoron

Every Car Trip Has Bad Impacts

This essay proposes that more traffic is bad, but congestion is good at every level of traffic. For those of us who are advocating for active modes of transportation—walking, rolling, cycling, and public transportation—traffic congestion is our friend. What is traffic? A sensible way of defining traffic is in terms of the number or volume of vehicles within a corridor segment within some timeframe. Some people might prefer a more expansive definition of traffic which includes people on foot. If such is the case, it is better to single out motorized traffic because cyclists and pedestrians are not the problems.

The climate and health impacts from vehicles running on internal combustion engines (ICEVs) are well known. According to the US Environmental Protection Agency, “a typical passenger vehicle emits 4.6 metric tons of CO2 annually.” Tailpipe emissions from ICEVs combine with Volatile Organic Compounds (VOCs) to create ground-level ozone, which is a lung irritant, and can cause throat irritation and congestion, and aggravate asthma, bronchitis, and emphysema.

On the other hand, the Biden Administration is promoting the transition to Electric Vehicles (EVs), which do not burn fossil fuels and have no tailpipe emissions. However, EVs also have climate, health, and safety impacts. While EVs do not burn fossil fuels, they do draw electricity from the grid, so it is fair to attribute to EVs the share of electricity generated from fossil fuels. Since that electricity includes renewables, switching from ICEVs to EVs has a climate benefit, but not as much as the benefit of abstaining from motor vehicle use. There would also be a significant public health benefit from switching from ECEVs to EVs. Tailpipe emissions would be eliminated, but just as with CO2, we need to consider the impacts of electricity generation. Even more important, tailpipe emissions are not the only health impact from motorized vehicles. We are inhaling plastic microparticles from brake and tire wear, which is the majority of all particulate pollution from ICEVs. In summary, EVs mitigate some of the climate effects of ICEVs, but not all of them. However, it is not clear that EVs improve public health.

Crash risk posed by motorized vehicles is the elephant in the room that few people want to talk about. While the long-term trend in US traffic safety has been decreasing fatalities/million miles traveled and fatalities per capita, total crash fatalities in recent years are over 40,000. In addition, pedestrians have faced the greatest risk in recent years. Cycling and walking have no environmental impact, so increasing these transportation options is a critical piece of climate policy. Therefore, transportation improving safety for people walking, rolling, and cycling is climate policy, too. Putting climate aside for the moment, we should reconsider our tolerance for >40,000 crash fatalities per year in the US. Increasing traffic increases maiming and death.

More traffic implies more CO2. More traffic degrades public health. More traffic degrades public safety. QED: more traffic is bad. Recall that more traffic means adding the volume of vehicles to a corridor within a given time frame. Yet drivers often speak equivocally about traffic. It’s understandable. Drivers are not trying to solve climate, or public health and safety. They are only attempting to maximize their mobility. With this goal in mind, it implies that their problem is any obstacle to their mobility. That’s why traffic congestion is their problem. They are not concerned by too many cars. As drivers, they are only concerned about the cars which are in their way.

As active transportation advocates, we should not make traffic congestion our problem. The political possibilities of an alliance to fight traffic congestion are tempting to us. Drivers hate traffic congestion. We hate traffic, and traffic congestion is a type of traffic. It looks like a winning political coalition. Except that it would only be a win for driving and car dependence. Traffic congestion is our ally. It has two important effects. First, it is safer than free-flowing traffic because cars are moving slower. Even if drivers attempt reckless maneuvers to escape traffic congestion, the damage they can do is limited compared to the damage they can do in free-flowing traffic. Second, the climate and emissions impacts are not increased by congestion. This addresses a myth promulgated by the Road Warriors: idling is bad for the environment. Local and regional governments often use this as a justification for expanding road capacity. There is even a category of federal transportation grants that these governments exploit to fund road expansions: Congestion Mitigation-Air Quality funds. Expanding capacity, however, induces traffic and more traffic implies more particulates and more energy use.

The Coffee and Tea Problem

The modal share problem can be understood in microeconomic terms. Transit has a coffee and tea problem. Just as nobody consumes a cup of coffee while they are consuming a cup of tea, nobody walks, rolls in a wheelchair, rides a bicycle, or uses public transportation while they are driving, and vice-versa. Coffee and tea, and transit and driving are pairs of perfect economic substitutes. Increase in the demand function for one decreases the number of units demanded the demand function for the other. Therefore, any support for driving—such as increasing the supply of free parking and expanding the number of general purposes lanes on roads—reduces demand for transit and other active modes. There is no way to encourage active transportation while making it easy and cheap to drive.

If You Are Driving, You Are Traffic

As Tom Vanderbilt says, “You are not in traffic; you are traffic.” In other words, drivers think of other drivers being the problem, but they rarely see themselves as the problem. Drivers perceive other drivers as obstacles, but are less aware that they are other people’s problems. Most drivers intuit that traffic is dangerous and degrades quality of life, but do not apply this understanding to their own driving behavior. Even people who live in suburbs and exurbs generally agree that more traffic is bad in the sense that it is bad to live on a high-traffic road. Subdivision developers have been designing street networks to inhibit traffic for over a century. A early attempt at the regulation of traffic through street design was Vandeventer Place in St. Louis, sometimes known as a private street or private place. While there are several other private streets in St. Louis, these were elite subdivisions that never gained much popularity. Courtlandt Place is an example of a private street in Houston.¹

Suburbanites Discourage Driving Where They Live

In the early twentieth century, subdivision developers continued to court elites, but to a lesser degree. This generation of subdivision was larger than the private streets and employed a new technique for controlling access. These subdivisions required street networks to serve the number of lots developed, but they often carved local streets with minimum disruption to the natural topography, leading to aesthetically pleasing hills framing curvilinear and sometimes meandering streets. A driver attempting to cut through might easily lose their direction. These subdivision sometimes limited points of ingress to and egress from the subdivision. Subdividers designed their street networks to restrict access to non-residents in order to inhibit traffic. This generation of subdivisions includes Roland Park, Baltimore; Palos Verdes Estates, Orange County, CA; and the Country Club District, Kansas City, MO. In the 1920s, these elite subdivisions included Highland Park, Dallas; and River Oaks, Houston.²

The most well-known example of a subdivision with a street design to inhibit traffic is Radburn, NJ. The early generation of subdivisions of subdivisions were only somewhat successful at inhibiting traffic. Subdivision planner Clarence Stein combined the bending roads used in the Country Club District, but also limited the number of access points to each node of development. By allowing only two access points to each node, there was no advantage to cutting through Radburn. This effectively limited traffic. Limiting access has been a common feature of subdivision planning for the last seven decades. Clearly this is a feature attracting people to living in the suburbs. Yet, what suburban dwellers desire for their own lives, they deny for urban dwellers.³

For those who are concerned about reducing impacts on climate and improving public health in the US, we need to understand that more traffic is bad and congestion is not our problem, and is really our ally. This is sensible only if we distinguish traffic from traffic congestion. If we care about climate and public health, we need to reduce traffic. Traffic congestion might frustrate drivers enough to consider other options.

1. Cheryl Caldwell Ferguson, Highland Park and River Oaks: The Origins of Garden Suburban Community Planning in Texas (Austin: University of Texas Press, 2014), 39-40, 50-52.

2. Robert Fogelson, Bourgeois Nightmares (New Haven: Yale University Press, 2005), 11-13, 26, 40-42, 110, 208-209; William S. Worley, J. C. Nichols and the Shaping of Kansas City: Innovation in Planned Residential Communities (Columbia, MO: University of Missouri Press, 1990), 31-32, 98-101, 176; Kenneth T. Jackson, Crabgrass Frontier: The Suburbanization of the United States (New York: Oxford University Press, 1985), 178-179; Ferguson, Highland Park and River Oaks, 179.

3. Michael Southworth and Eran Ben-Joseph, Streets and the Shaping of Towns and Cities (New York: McGraw-Hill, 1997), 59-69; Dolores Hayden, Building Suburbia: Green Fields and Urban Growth, 1820-2000 (New York: Vintage Books, 2003), 124; Worley, J. C. Nichols, 107.