With Elaine Chao’s confirmation as Secretary of Transportation last week, more focus is going to be placed on exactly how to revamp transportation infrastructure in the U.S.

On the cusp of what should amount to a massive investment in roads, bridges, and airports, it’s important to note the areas which can use the most improvement.

The Bureau of Labor Statistics (BLS) updated its quarterly compendium of data related to travel and the state of U.S. transportation infrastructure, opening a window into the areas of concern that should be approached by a potential impending spending bill.

Most notably, it’s aging roads and bridges that pose the greatest threat to continued travel around the U.S., not a crummy experience at airports nationwide.

Here are three takeaways from the report.

Increased traffic is causing more bridges to fail

While the sorry state of U.S. airports tend to generate the most negative impressions for travelers, the state of the country’s roads and bridges are more troubling, according to BLS statistics.

Old bridges, in particular, are a cause for concern; there were 12,241 bridges in 2015 that are more than 100 years old, and 67.3 percent of those are deficient. Nearly half (44.8 percent) of the 72,898 bridges between 76 and 99 years old are deficient as well.

“The condition of the U.S. transportation infrastructure is improving, but additional work is needed,” states the report. “The percentage of structurally deficient bridges declined from 12.0 percent in 2010 to 9.6 percent in 2015.”

Overall, there were about 120,000 total bridges in the U.S. considered deficient as of 2015. As highway usage has surged in recent years, the result of more cars on the road and cheaper gas prices, the system has become more strained.

Airport infrastructure has slowly improved

Most U.S. airports are solid from a structural and technical standpoint, even if the experience for flyers has gotten worse in recent years. Just two percent of commercial airports have runways in poor condition, a decrease from five percent in 2000.

“Most airport pavements (commercial service, reliever, and select general aviation) were in good condition between 2000 and 2014, with only 2 percent rated as poor,” reads the report.

The aircraft used by carriers across the country also became younger over the past few years, but delays are still caused by an outdated air-traffic control system that is currently under transition to more advanced technology.

Public Transportation is crumbling

Public transportation, which has become more widely used across the country in recent years, needs much more investment before it can accommodate the higher ridership numbers transit systems are currently burdened with.

To keep up with growth, the government would have to invest billions more annual to keep public transit systems around the country in good repair:

“According to USDOT’s biennial conditions and performance report, the current total investment across all transit systems is $16.5 billion annually Bringing all systems to a state of good repair would require an increase to $18.5 billion per year. However, increasing system capacity to accommodate higher transit ridership would require an estimated $22.0 billion to support a 1.4 percent annual ridership growth rate versus an estimated $24.5 billion to support a 2.2 percent annual ridership growth rate.”

It’s unlikely continued investment into public transportation will be a priority for the Trump administration or Congress, however, given recent statements. Systems like Metro in Washington, D.C., are now beset by daily delays and safety hazards.

Photo Credit: Despite talk of the need to improve U.S. airports, data show that highways and bridges are in dire need of improvement. In this May 17, 2012 file photo, the steel skeleton for the eastern end of the new Innerbelt Bridge in Cleveland sits next to the existing span. Mark Duncan / Associated Press