Will fixing America's infrastructure help repair the economy?

President Barack Obama on Wednesday reiterated his call to fix America's aging roads, bridges and other infrastructure, noting that such projects also create good jobs.

"Over the past 50 years ... our investment in transportation has shrunk by 50 percent," he said during an address at the new Tappan Zee Bridge construction project north of New York City. "You know what other countries are doing? European countries now invest twice as much as we do. China invests four times what we do in transportation."

But how much do such projects really contribute to the U.S. economy? In 2012, 14.2 million workers were employed in infrastructure-related jobs in the U.S, The Brookings Institution said in a new report. That amounts to about 11 percent of all workers. The majority of those jobs were to be found in America's 100 largest urban areas.

Workers in infrastructure occupations also earn significantly higher wages compared to the rest of the national work force, according to the public-policy think tank. In terms of education, only 12 percent of infrastructure workers hold a bachelor's degree or higher, but over 80 percent have had on-the-job training.

Overall, infrastructure jobs are expected to increase by more than nine percent over the next decade.

"Many infrastructure jobs are projected to grow by thousands of additional workers," Brookings said, "led by fast-growing occupations such as wind turbine service technicians and solar photovoltaic installers. Critically, though, there will be a need to replace almost one quarter of this infrastructure workforce due to retirements and other employment shifts," or more than 2.7 million workers.

Experts have warned for decades that America's infrastructure is in desperate need of renovation. Last year, the American Society of Civil Engineers gave the national infrastructure a grade of D+, while estimating the U.S. would need an estimated $3.6 trillion in investment by 2020 to deal with its infrastructure problems.

"We have ports that aren't ready for the next generation of cargo ships," Obama said on Wednesday. "We've got more than 100,000 bridges that are old enough to qualify for Medicare. We've got leaky pipes that lose billions of gallons of drinking water every single day, even as we've got a severe drought in much of the West. Nearly half our people don't have access to transit at all. And I don't have to tell you what some of our airports look like."