I-15 expansion prompts concerns about pollution, business impacts, and traffic congestion

Looking down on I-15 near 1000 North. UDOT’s current proposal includes a new full interchange near this location, which could result in the removal of businesses in the area. Photo by Elisabeth Cupp.

While community members seemed pleased at the Utah Department of Transportation’s (UDOT) May 2023 commitment to not demolish any homes while expanding Interstate 15, many remain concerned with the overall plan to expand the freeway, with some vocalizing concerns about air and noise pollution, economic disruptions to local businesses, and increased traffic congestion.

Concerns about air and noise pollution

Many of the concerns with air quality stem from particulate matter 2.5 (PM2.5), which is a particle of emissions that causes the greatest health concerns, especially in children. Researchers at the University of Colorado, who are currently partnering with local universities and groups to study air pollution in the Salt Lake Valley, say roughly half of the PM2.5 comes from automobiles. “Vehicles cause around 50% of the PM2.5 in Salt Lake County, making them a big contributor to its air pollution issues,” wrote the researchers in the Spring 2023 edition of The West View.

The Union of Concerned Scientists says some PM2.5 pollution forms directly during combustion in a gasoline- or diesel-powered vehicle, and is present in vehicle exhaust. Additional PM2.5 particles are generated by brake and tire wear as well.

The Rose Park Community Council, in a statement released in January 2023, expounded upon the concern of air pollution, saying, “The goal of highway expansion, it seems, is less around the urgent concerns of our health and well-being and more around the ease and convenience for cars – especially commuters from other cities.”

The Rocky Mountain Institute found that from 1993-2017, new freeway lane-miles added in the largest 100 cities increased 42% and the population rose 32%, yet freeway traffic increased by a whopping 144%. Using the same formula, one could calculate that widening I-15 would increase vehicle miles traveled from 529 to 794, resulting in a nearly 50% increase in both emissions and noise.

Increased noise pollution is another issue that could result from freeway expansion. The Centers for Disease Control and Prevention (CDC) says any noise that creates decibels (the metric for noise) over 70 for an extended period of time can damage a person’s hearing. Decibel readings across the West Side consistently come in between 65 and 80 decibels at various times throughout the day.

Peak travel hours in the morning and evening regularly have decibel readings higher than 70. If I-15 is expanded, induced demand theorizes that additional cars will be on the road, resulting in more vehicle traffic. This will lead to even higher decibel readings during peak travel hours as car traffic increases and those times of heavier travel increase as well. For those living near the freeway, it means an increased risk for permanent hearing damage, a risk UDOT seems willing to take.

When it comes to air pollution, UDOT doesn’t appear very concerned. The FAQ section of the I-15 EIS website speaks to this concern, saying in part, “Generally, emissions from cars and trucks that contribute to our air quality challenges will continue to decrease even as we grow, thanks primarily to improvements in vehicle technology.” The statement continues, “Our study will assess the effect of any proposed project on the overall air quality in the region as part of the Regional Transportation Planning process.”

Concerns about impacts to businesses

Not only do businesses near the interstate need to worry about potentially losing their physical location, they also need to be concerned about years of construction in the area.

These construction disruptions include impaired access to store fronts, disrupted supply chains, and changes in road access routes, all of which have the potential to significantly reduce business revenue.

While UDOT has not fully disclosed the complete construction process of the project, looking at previous projects can help put things into perspective.

Between 2008 and 2013, the reconstruction of North Temple due to the extension of UTA’s Green Line TRAX train to the SLC Airport resulted in mass disruption to local businesses. Much of this came from street closures required for construction to commence. For example, the restaurant Red Iguana reported a loss of more than $600k during this time, citing construction cutting off routes for customers as the primary reason.

Between 2017 and 2018 (and still continuing today), UDOT expanded Bangerter Highway in the middle of the Salt Lake Valley. This construction process has required the acquisition of more than 100 properties in order for construction to go forward. While UDOT currently claims no properties will need to be acquired for the I-15 expansion, it’s not something they’re able to guarantee at this time.

At the June 2023 listening session, a representative of the Utah Independent Business Coalition asked UDOT and state representatives about the overall impact on businesses due to these expansion plans. While a brief about the economic impact is set to be included in the Environmental Impact Statement, there’s no requirement to do any kind of in-depth analysis. As such, there are no plans in place to critically consider the impact expanding the freeway will have on local businesses.

Concerns about traffic congestion

Construction activities often lead to increased traffic congestion, as lanes become blocked and drivers move onto side streets looking for faster alternatives. This construction can slow down the flow of vehicles and increase travel times for employees, customers, and suppliers.

Even once construction is finished, it’s not likely that traffic congestion will decrease in the long-run. Research from several sources show that having more freeway lanes actually increases traffic within one to three years after construction, thus causing more congestion in the long-run.

The theory of induced demand, or induced traffic, looks at this very issue, and says that adding additional lanes of travel will lead to increased traffic as more vehicles choose to use roads containing more lanes.

HEAL Utah, a group focused on improving the overall environment in the state, echoed similar concerns in a call-to-action page recently posted on their website. “UDOT’s stated intention is to relieve traffic congestion and repair infrastructure along this route,” the statement reads. “However, with induced demand, the expansion could result in increased traffic congestion and accidents, negatively affecting the surrounding communities.”

Additional information on the project, as well as a full range of FAQs, can be found at https://i15eis.udot.utah.gov/.