DAVIS COUNTY, Utah (ABC4) – The Utah Department of Transportation is exploring options to help ease traffic flow and increase safety along the I-15 corridor, specifically through Davis County. Currently, the plan favored by UDOT includes widening I-15, but will it actually help?

In the most recent update from UDOT‘s Environmental Impact Study (EIS) process, the department said it’s leaning towards the “narrowest option” for I-15 redevelopment. This option would see UDOT widen I-15 to five lanes with one express lane.

UDOT says widening the freeway will help ease traffic for commuters trying to reach Salt Lake City and back. According to its report, travel time for commuters would be reduced by about 50% and average speeds during peak commute times in the morning and evenings would increase anywhere from 95% to 125%.

However, widening freeways isn’t new, and while it does help alleviate traffic for a short time, research shows the delays will return eventually.

The Katy Freeway, a segment of I-10 in Houston, Texas, for example, was once named the “second worst bottleneck” of the nation. According to a 2020 Congestion Report from Transportation for America (T4America), Katy Freeway would see congested conditions for up to 11 hours each day. The Texas Department of Transportation worked to expand the freeway, increasing its capacity to 23 lanes in 2008.

By 2011, travel times reportedly steadily began increasing again. One 35-mile trip out of downtown Houston took an estimated 47 minutes during peak rush hour in 2011 T4America reports. By 2014 – just three years later and six years after the widening project was completed – that same trip took 70 minutes.

T4America said the United States has added 30,511 new freeway lane miles in the largest 100 urbanized areas between 1993 and 2017. They say the strategy to simply add more freeways for congested areas has “utterly failed to ‘solve’ congestion.”

Salt Lake City reportedly saw a 16% increase in new freeway lane miles between 1993 and 2017 with a 32% increase in population, according to the Congestion Report. Despite the attempt to ease traffic congestion, Salt Lake reportedly had a 279% increase in traffic delays during that time.

In addition to an increase in traffic delays, widening freeways would add to air pollution. According to Rocky Mountain Institute (RMI), about 4.1 billion vehicle miles are traveled on I-15 per year. Adding just 10 more lane miles to I-15 would see up to another 47 million vehicle miles. RMI estimates the annual emissions of this increase would be the same as 4,900 passenger cars and about three million gallons of gas.

RMI said that widening the freeway does help with freeway traffic, but research shows that the reduction in traffic is short-lived. As shown by the Katy Freeway project, RMI said traffic congestion is usually back within five to ten years.

So why does data show freeway widening doesn’t work? According to T4America, there are multiple reasons.

First, people are driving more. In 1993, the average person drove 21 miles per day compared to the 25 miles per day in 2017. T4America also said city development – what we build and where – is creating greater distances to drive and increasing commute times. Along the same lines as city development is the lack of redevelopment of smaller local streets. T4America said without a good local network, cars pile onto major roads, even for shorter trips.

“The Katy Freeway paints a stark picture: there is no amount of new lanes – and no amount of money poured into widening highways – that will solve our traffic problems,” wrote T4America in its report. “We need a different approach.”

For its own project on I-15, UDOT said it will need to expand all travel options in order to meet expected population growth in Salt Lake City by 2050. According to the project’s website, UDOT will work closely with UTA, local governments, and planning agencies to create more choices of transportation but says widening the freeway is required to meet expected travel demands.

To fix the problem, T4America recommends changes to policy when it comes to roads. T4America said officials should prioritize investments that make travel more efficient, not faster. T4America also recommended transportation agencies should start favoring road maintenance and building a strong network on local roads as opposed to building new roads and highway expansions.

Breakdowns by region of the I-15 can be found on the project’s Facebook page while a more detailed rundown of the I-15 project can be found on UDOT’s website.

UDOT is still in the phase of drafting its EIS. Once released, it will be open for a 45-day public comment period which will include public hearings to explain the findings.

The draft is expected to be available in Fall 2023.