Abstract
Highway expansion has persisted across the last several decades in the United States. While these networks provide an important mode of transportation for people and cargo between major cities throughout the country, their expansion poses an ethical dilemma. The primary solution to bottleneck traffic congestion and prolonged commute times is to add extra lanes to existing highways; however, the relief is temporary, as their positive effects only last about five years. Further, highway expansion has been associated with unethical long-term effects that prove federal budgets should be investing in improving existing road infrastructure.
Introduction
Highways are necessary for transportation, especially across the 48 contiguous states. Their importance grew exponentially in the late 20th century as the 1950s to late 1990s saw the nation’s highways expand from 341 miles to 43,420 miles across the country [1]. This increased access to individual transportation allowed for easier travel, especially within county lines, for the ordinary person. Along with this came economic development via the spread of goods, services, and people across state lines. Nowadays, the most complex highway systems exist to connect major metropolitan areas with their surrounding suburbs.
Since the development of highway systems, cities have grown increasingly decentralized. Cars and highways have provided individuals the ease of daily driving in and out of the city. Even if one’s job is in the city, there is no longer a need to live there. A 2020 MIT report on urban expansion states that between 1960 and 2000, the central cities of the largest U.S. metro areas fell from housing 49% of their populations to housing a mere 24% [2]. Commonly, wealthier, White individuals were moving to the suburbs as they could afford more expensive housing and the temporal and financial burdens of the daily commute, such as childcare and gas expenses.
The Problems Presented by Highway Expansion
A big problem is the disparity between the cost of housing versus the financial capabilities of workers. Commercial and industrial development are high revenue generating, but they drive up the cost of housing. Those who work in these job centers are usually unable to afford nearby housing and, instead, are forced to reside in and around the central city where housing is denser and cheaper [1]. Better-paid, inner-city businesspeople can afford to live on the larger, more expensive land in the suburbs [1].
Furthermore, this decentralization has resulted in an imbalance in the ideal ratio of housing to jobs. Ideally, for every job in the area there should be 1.5 housing units [1]. If there are more houses in an area than there are jobs available, residents will be forced to look elsewhere for work. When the ratio is skewed in the opposite direction, workers are unable to live in close proximity to their jobs. Studies in Atlanta, Chicago, and San Francisco all found that housing-job imbalances created by suburbanization have resulted in longer commutes and increased regional traffic congestion [1]. Increasing highway capacity is most often the proposed solution to this problem.
The majority of modern highway expansion projects focus on adding lanes to address congested roadways in and around major metropolitan areas. Lane additions are thought to mitigate traffic between these job and housing-intensive communities; thus, they help expand economies. While interactions between states, suburbs, and city centers do promote economic growth through the shared availability of goods and services, most of the interstate system used to conduct this travel has been complete since the 1970s [3]. Their further expansion is not contributing enough revenue to justify the money and environmental costs spent on them. A 2012 study used data gathered between 1984 and 2005 in the 48 contiguous states to determine that every dollar increase spent on expansions returns only a $0.15 increase, measured in the dollar value of 2000 [4]. Highways are no longer boosting the economy; they are merely redistributing wealth. Yet expansions persist.
The Bipartisan Infrastructure Law
In spite of the low return on investment from highway expansion, current legislation promotes it. In March of 2023, a two-year civil rights complaint was resolved, allowing for the continued expansion of Interstate 45 in downtown Houston, Texas. The North Houston Highway Improvement Project intends to address traffic congestion and boost the city’s economy by adding four express lanes to the highway.
Still, the plan fails to consider those affected by this expansion. Predominantly Black and Latino neighborhoods will be demolished, displacing 1079 homes, 344 businesses, and two schools [5]. The project attempts to combat this by committing $27 million to developing new affordable housing in the area, yet residency is not directly promised to these families [5]. Furthermore, history shows that highway expansions do little to combat traffic congestion effectively and, instead, worsen the air quality of the neighborhoods these projects cut into. Unfortunately, this is just one example of a multitude of expansions occurring across the country thanks to funding unintentionally provided by the Bipartisan Infrastructure Law.
The Bipartisan Infrastructure Law, also known as the Infrastructure Investment and Jobs Act, was signed into law in November of 2021. It will invest approximately $550 billion into the nation’s infrastructure, with around $350 billion going toward federal highway programs over the next five years [6]. Ideally, this money would go towards repairing existing roads, highways, and bridges and making streets more accessible for those walking, biking, or using public transportation. However, the ultimate use of resources cannot be federally predetermined, and recent trends in some state government investments show excessive amounts of funding into highway expansion projects [7].
Nonetheless, the utilization of this funding for highway expansion has raised ethical concerns, especially because Texas isn’t the only state looking to expand its highways. Several road expansion projects currently under construction include the widening of I-205 in Oregon, I-95 and I-395 in Florida, I-75 in Michigan, and I-83 in Pennsylvania [8]. This list is not all-encompassing, and the Public Interest Network recently published a list of 65 different projects that have been proposed in the last eight years [8].
Highway Expansion and Greenhouse Gas Emission
All of these expansions intend to improve the peak-hour traffic that bottlenecks during morning and evening commute times. That’s because cars emit greater amounts of carbon dioxide when backed up in bottleneck traffic. Carbon emissions from vehicles project a bell-curve trend in relation to speed. Slower, stop-and-go speeds, around 20 mph, and really high speeds, 60+ mph, contribute to more greenhouse gas emissions than a steady average speed, which is around 30-40 mph, thus supporting the idea that increased capacity could lessen carbon emissions by allowing for slightly higher speeds during peak traffic hours [9]. Studies conducted immediately after the completion of road expansion projects show a reduction in carbon emissions due to improved traffic flow. However, these results are only temporary.
The Fundamental Law of Road Congestion renders the increased capacity speeds unsustainable in the long term. Published in 1962 by Anthony Downs, this law, also understood as induced demand, argues that over a period of time, “rush hour traffic speeds tend to revert to their pre-expansion levels” [10]. This implies that as highways add lanes, the improved road and traffic conditions will encourage more individuals to drive on them, negating the original attempt at lessening congestion. Further studies confirmed this and determined that the time in which the congestion reverts to or, in some cases, exceeds the original traffic congestion is approximately five to ten years [10]. Unlike the temporarily increased speeds, the harmful effects of these emissions are permanent. They will continue to impact the environment and people long after induced demand runs its course.
The subsequent increase in carbon dioxide emissions is the most important takeaway from the Fundamental Law of Road Congestion. As of the 2022 Congressional Budget Office Report, emissions of CO2 were highest from transportation, totaling 1.7 billion metric tons, or 38% of the total energy-related emissions from the economic sector [11]. While CO2 emissions are on a downward trend overall, reductions in the transportation sector, in particular, are not visible [11]. Highway capacity expansions provide an opportunity for the nation’s civil engineers to alter the direction of these trends. Carbon emissions that occur from expansion projects impact global climate change and human health. On the micro-level, the environmental impact of these projects also contributes to ethical issues of justice and fairness.
Inequities of Highway Expansion
Highway expansion projects typically have the greatest negative impact on marginalized groups. The findings of a study conducted on the Tampa Bay Next project in Florida showed that existing inequalities of traffic-related air pollution are exacerbated [12]. Compared to individuals who are wealthy and White, individuals who are living in poverty or Black are disproportionately exposed to the pollution caused by this project [12]. This mimics the spatial inequalities of the Houston I-45 expansion, which intends to displace residents of the Fifth and Third Ward, historically Black and Latino, low-income neighborhoods [13]. By building in and near these communities, carbon emission rates are likely to rise from both construction and the driving that will ensue. Prolonged exposure to these conditions has adverse health effects.
The effects of suburbanization, along with the original placement and function of freeways as means to filter people in and out of urban cores, disproportionately impact individuals from historically lower socioeconomic backgrounds, placing them at a greater risk of experiencing adverse effects from highway expansion [4]. Highway expansions create issues such as air pollution, noise pollution, green space inaccessibility, and decreased transportation flexibility that cause major health conditions. Increased air pollution can result in health problems such as asthma, cardiac effects, reduced lung function, premature mortality, and lung cancer [14].
The Children’s Health Study determined that kids living within a city block approximately 75 meters from the nearest freeway are 1.5 times more likely to report having asthma than those living 300 meters from a major roadway [15].
Another study measuring noise pollution throughout Chicago, Illinois, found that areas closest to highways registered over 70 decibels, exceeding the World Health Organization’s recommended guideline of 55 decibels [16]. These areas were also noted as being middle-to-low income [16]. Prolonged exposure to unwanted noise has been associated with increased blood pressure, elevated cortisol levels, and disrupted sleep patterns, all of which are potential contributors to the development of mental health conditions [17]. Decreased access to green spaces may also have adverse effects on individuals’ mental well-being. Finally, reduced safety due to increased traffic may limit the ability to partake in outdoor physical activity or other modes of transportation, such as walking and biking. These effects disproportionately impact residents of the neighborhoods near highways or where highways are being expanded into.
The Civil Engineer’s Ethical Obligation to Fight Highway Expansion
Per the civil engineering ethics code, these inequalities and environmental concerns should deter expansion projects from being taken on. Civil engineers are obliged to “adhere to the principles of sustainable development” and “mitigate adverse societal, environmental, and economic effects” [18]. Thus, with $550 billion donated to infrastructure, there are more useful ways to allocate these funds, such as repairing old or poor-quality roads. As of a 2021 infrastructure report, there is a backlog of $435 billion worth of road reparations needed throughout the country [19].
While improving the quality of roads may not decrease the volume of drivers, it may increase efficiency on roadways, which could have a larger impact on traffic patterns overall. A 2006 Pacific Institute for Research and Evaluation study revealed that deteriorating road conditions, characterized by cracks, potholes, missing guardrails, and other changes in a road’s surface, are responsible for 59% of road accidents annually [20]. These accidents often take significant time to clear, causing traffic backups. Additionally, fixing smaller roadways with poor conditions may encourage drivers to use a route other than the overpopulated highways. Changing the focus to fixing what already exists, rather than building new roads, can improve both travel times and driver safety.
Not only can fixing physical problems improve roadways, but altering street design may aid in traffic congestion as well. Investing money into “complete streets” could revitalize urban and potentially even some suburban areas. These streets would provide spacious walking and biking paths in conjunction with existing streets [19]. Newfound accessibility and safety have been found to inspire residents to stay closer to home as they can simply walk or bike to where they are going [21]. When provided with quality alternatives, individuals take advantage of them, consequently lowering the number of cars and carbon emissions on the road as well as improving cardiovascular health [22].
Conclusion
Roadways are fundamental to a country’s infrastructure, especially one as large as the United States. Highways allow for increased interactions between citizens and sub-economies throughout the country and are not going anywhere anytime soon. However, reliance solely on lane expansions to address traffic congestion should be reconsidered. Furthering urban sprawl, increasing greenhouse gas emissions, and worsening the health risks of marginalized populations are unethical practices. Citizens and the environment suffer from the adverse effects of expansion long after highways’ capacities are increased. Meanwhile, aid provided to the traffic congestion that inspires expansions has an expiration date. Transportation planners need to shift gears and prioritize the well-being of vehicle occupants rather than solely emphasizing their speed.
By Karsyn Wendler, Viterbi School of Engineering, University of Southern California
About the Author
Karsyn is a student at the University of Southern California majoring in civil engineering with minors in dance and architecture. In writing this article, she was inspired by the vast highway network of her hometown Houston, Texas.
References
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Links for Further Reading:
Freeways force out residents in communities of color — again
A moving piece that displays the personal consequences of freeway expansion.
A comprehensive breakdown of Biden’s 2021 Infrastructure Investment and Jobs Act.