The need for increased infrastructure investment has been one of America’s few remaining bipartisan issues, although left and right differ over whether public money or private money would finance it. President Barack Obama made reinvesting in roads, bridges and power plants a cornerstone of the 2009 economic stimulus package, and during the 2016 presidential campaign seemingly the only disagreement Hillary Clinton and Donald Trump had on infrastructure was about which of their administrations would spend more on it. The issue unites truckers and train buffs, unions and Wall Street, economists from the left and right.

And yet, when it comes to spending the money — and actually getting things built — very little progress has been made. Following a brief spike during the recession, government investment has hovered around 3.3 percent of gross domestic product for the past few years, which is the lowest since the 1940s. In the meantime, roads, bridges and train tracks have gotten steadily older while proposals for new projects are delayed by political intransigence and legal delays.

America’s short-horizon election cycles, especially in the House of Representatives, are not in sync with the time it takes to build such massive projects, making them politically vulnerable.

In California, high-speed rail had been promoted by Republicans and Democrats alike for decades before the first shovel broke ground in 2015. It was Pete Wilson, a Republican governor, who in 1996 signed the legislation establishing the California High-Speed Rail Authority. Another Republican governor, Arnold Schwarzenegger, put the project’s financing on the ballot in 2008. Later, Gov. Jerry Brown, a Democrat, became the project’s biggest booster and funder. In the meantime, polls showed Republican support for the project eroding.

“There are so many obstacles to changing the status quo, and so many litigation opportunities at each stage, that we’re really looking at 20 years of consultants and lawyers and bureaucrats before these projects get started, and it’s almost impossible to maintain political and taxpayer support over that period,” said Jennifer Hernandez, a partner at Holland & Knight who leads the law firm’s West Coast environmental and land-use practice.