If a restaurant had a D grade from the health department on its window, it’s understandable to question whether you may want to look for another option.

But that’s exactly the situation many of the country’s public transit riders face on a daily basis. According to the latest American Society of Civil Engineers’ infrastructure report card, the country’s public transportation infrastructure earned a D minus, the lowest grade the ASCE gave to any category.

And, according to a new report released by the American Public Transit Association (APTA), barring a massive, multibillion-dollar investment by the federal government, that situation isn’t changing anytime soon.

The Economic Cost of Failing to Modernize Public Transportation paints a grim picture of the cost of delayed maintenance and underinvestment in critical regional transportation systems. The report notes that, after decades of failing to invest in preservation and upkeep, many of the country’s transit systems have now changed their definitions of success—“success came to be understood in terms of preventing failure, ensuring reliability and finding ways to keep service running without interruptions affecting users.” A 2013 analysis by the U.S. Department of Transportation found that approximately 13 percent of U.S. public transit assets were considered past their useful life.

The cost of underinvestment in public transportation Public transit system Investment needed to achieve state of good repair Estimate loss in local GDP without repairs over the next six years Public transit system Investment needed to achieve state of good repair Estimate loss in local GDP without repairs over the next six years Chicago Transit Authority $12.5 billion $25.2 billion Washington Metropolitan Area Transit Authority $6.6 billion $10.8 billion Metropolitan Atlanta Rapid Transit Authority $2.2 billion $4.4 billion Massachusetts Bay Transportation Authority $7.3 billion $15 billion Southeastern Pennsylvania Transportation Authority $5 billion $9.6 billion San Francisco Municipal Transportation Agency $2.4 billion $9 billion

The study, which contains six in-depth cases studies of some of the country’s largest mass transit systems, makes a compelling case for a true infrastructure week. Failure to act, the report says, could have dire consequences, and constrain transit systems around the country from making much-needed expansions to meet rising populations. The nation has an estimated $90 billion backlog in public transportation modernization needs, defined at the investments needed to achieve a “state of good repair.”

Failing to address those needs would cost the U.S. economy $340 billion in business revenue over the next six years. A recent study in New York City found that the city’s subway delays cost the local economy more than $1 million every day in lost productivity.

Compiled by the Economic Development Research Group, the report underlined how dilapidated rail and buses have become an even more dire problem due to changes in the perception of public transit. As highlighted by the Amazon HQ2 search, which places a lot of weight on a functioning mass transit system, a good transit system is a competitive asset for cities looking to attract new businesses and employees. The weight placed on transit underlines its importance for economic development and growth, and the potentially stifling effect of not addressing the lingering problem of overdue repairs and upgrades.

The report’s six cases studies show transit agencies struggling to find resources for repairs, and the ways under-investment exacts a toll on aged systems. San Francisco Municipal Transportation Agency and its BART trains have been strained by the huge rise in ridership. In Boston, the Massachusetts Bay Transportation Authority was hit hard by winter weather in 2015, resulting in extensive maintenance issues.

Not all of these issues could have been prevented with regular upgrades. But that lack of long-term investment has made them all worse, and constrained the ability of systems to adjust or expand (especially considering the high cost of this kind of infrastructure in the U.S. relative to other countries). The Chicago Transit Agency has a backlog of roughly $12.5 billion, which means that reinvestment “comprises the vast majority of CTA’s outlays.”

This lack of funding hits both buses and trains. A 2015 USDOT analysis found poor conditions in 40 percent of rail stations, 24 percent of maintenance facilities, 12 percent of bus stops, and one in ten buses.

During a press conference earlier today, leaders of the APTA and local transit agencies profiled in the report said that federal action is required to make needed changes. While many cities have raised sales taxes and passed bonds to invest in more transportation spending, transit leaders argued that adequate upgrades can’t happen without federal spending, which comprises 44 percent of public transit spending.

States and cities have begun to make significant investments to meet the challenge of these aging systems, raising ballot initiatives, local gas taxes, and other ways to boost transit funding. According to the APTA, 70 percent of local ballot initiatives to raise local transit funding have been passed in the last decade—90 percent last year—in 2016, local governments raised $200 billion for transit funding.

In Philadelphia, Act 89, a state law signed in 2013 that doubled the agency’s capital budget. It’ll still take 15 years to bring the system up to speed in terms of delayed maintenance, but the law has given SEPTA a “new lease on life,” said Jeffrey D. Knueppel, the agency’s general manager. In Los Angeles, taxpayers voted for a sales tax increase in 2016, known as Measure M, that’ll bring hundreds of millions in transit funding annually.

But, as many of the transit officials noted, their regions need better transit to stay competitive, and they simply need more federal action and money to make that happen. Recent infrastructure proposals from the Trump administration, which focus more on highways and rural infrastructure as well as revenue-generating projects, and ask state and local partners to invest more in large projects, fall short of this plea for help, officials said.

“In many cities and states, we are stepping up,” said Edward D. Reiskin, director of transportation for the San Francisco Municipal Transportation Agency. “We need a partner. We’re not going asking for a handout, but we need a partner to invest in the infrastructure that our cities need.”