It could be the summer's biggest thriller: Will America's vacationing throngs make it to their getaway destinations and back before highway and transit projects across the country come to a screeching halt? Or will travel delays caused by aging infrastructure strand our heroes somewhere between their goal and home?

The I'm Stuck app messages members of Congress when users report delays.

Travel lags are a drag on the economy
In mid-June, the U.S. Travel Association trade group ran the numbers on how many people skip air travel because they fear delays. It also looked at how much money that's costing the travel and tourism industry, as well as the broader economy.

According to the survey and economic analysis, delays and cancellations are by far the biggest concern among domestic air travelers, leading flyers to skip 38 million trips last year. Between the lost travel revenue and the cost to passengers of delays they experienced, the economy took a $35 billion hit.

Hemmed in by aging infrastructure
Why are there so many holdups? While countries like China are leapfrogging to the head of the fast-traveling pack with high-speed rail lines and new airports, the U.S. lags in ways that make travel -- as well as daily commuting -- time-consuming and tedious.

It's also sometimes downright unsafe, especially when it involves a "functionally obsolete" road bridge like the I-5 Skagit River Bridge that collapsed last year in Washington State, or the "structurally deficient" I-35W Mississippi River Bridge in Minneapolis that killed 13 people when it collapsed in 2007. According to the American Society of Civil Engineers, or ASCE, more than 66,000 U.S. bridges are rated structurally deficient.

The ASCE also gave the country's airports and aviation system a grade of "D" last year, due to outdated facilities and technology. That's why the watchword among travel industry leaders is "infrastructure." The U.S. needs a major overhaul to remain competitive at home and internationally. Some of the needed upgrades can come from business, but for others, federal support and funding are a must. Here are three companies that are working to remedy the infrastructure problem now and for the long haul.

United's faster customs fix
United Airlines
(NASDAQ:UAL) in June installed 20 new automated passport control kiosks in Newark Liberty International Airport. These allow incoming U.S. and Canadian passport holders to take care of customs declarations and passport scanning faster. How much faster? Vancouver Airport Authority, which makes the kiosks under the BorderXpress brand, says the average reduction in customs wait time is 89%.

The airline says it will bring 10 more kiosks online at Newark over the course of the summer. United installed the BorderXpress kiosks in Houston and Chicago last year.

Scanning for airport bottlenecks
Lockheed Martin
's (NYSE:LMT) BlipTrack technology is rolling out at the Cincinnati/Northern Kentucky International Airport this summer to help spot and reduce delays in security lines. The system will track passengers' Wi-Fi and Bluetooth-enabled devices to provide a clear picture of how crowds move -- or don't -- through the security area and terminals. BlipTrack is already in use at selected airports outside the U.S.

These are smart fixes at the airport level, and if they work as hoped, we should see them rolled out at more airports. But air travelers aren't the only ones who get bogged down. To address transportation issues of all kinds, the U.S. Travel Association and the Build America's Future lobbying group have just released a new app called "I'm Stuck."

Asking Congress to get unstuck
Marriott International
(NASDAQ:MAR) CEO and President Arne Sorenson is among the business leaders promoting "I'm Stuck." Sorenson's June 30 LinkedIn blog post urged readers to use the app to send real-time alerts to their U.S. representatives whenever they find themselves gridlocked on the freeway, at the airport, or on late subways, trains, and buses. There's even an option for bicyclists who are stuck without a safe way to proceed to their destination.

"If more of our elected leaders understood just how behind we are on this, they may join the current efforts or come up with their own," Sorenson wrote. "Let's tell them how bad it really is."

The goal is to get the House to take some action on funding upgrades and developing new infrastructure. Sorenson isn't alone. President Obama on July 1 made a public plea to the House to get moving before the federal Highway Trust Fund goes broke at the end of next month.

Without the Highway Trust Fund to supply states with the federal share of highway project money, more than 100,000 road and transit projects could have to go on hiatus. The federal transportation department says that would cost 700,000 workers their jobs. And it would leave even more Americans stuck as the summer vacation season comes to a close.