The Obama administration wants to bet about $100 billion in federal tax revenue on a pair of high-tech transportation initiatives that could take decades to come to fruition, but could make dramatic improvements in the speed, safety and efficiency of goods and people moving around the country. One is a new network of high-speed passenger rail lines. The other is a new air traffic control system.

The White House sees both as vital to U.S. economic competitiveness for the better part of the 21st century, but each effort will be enormously complicated and require shifts that are as much cultural as technical.

A new satellite-based GPS system for regulating traffic in the skies would permit more planes to safely occupy the same slivers of airspace, which will be essential as airborne shipping fleets and commercial airlines try to keep enough aircraft aloft to accommodate the growing economy and increasing population. On the ground, the administration envisions a new generation of rail engines zipping many thousands of people every day between major regional economic centers — and doing so more quickly, cheaply and efficiently than short-haul jet flights.

But the amount of federal money required is staggering by any measure — and it would have to be carved out during tough times for domestic discretionary spending. The air traffic control system, known as “NextGen,” is estimated to cost upward of $40 billion; the president is calling for spending $53 billion on his high-speed rail dream just in the next six years.

In the case of the new air traffic control system, there are also questions about whether the Federal Aviation Administration is up to the task of achieving such a monumental technological upgrade. And the airline industry is sounding reluctant to make good on its end of the arrangement — spending billions of dollars to equip its planes to communicate with the new system — absent a more compelling case for how the change will help their bottom lines.

There isn’t any cost-sharing envisioned between industry and the federal government as part of the president’s rail initiative, which essentially means the idea is not going any further as long as Republicans have some control of Congress. And the enormous potential costs have already prompted three states — Ohio, Florida and Wisconsin — to turn down the initial federal grants that were coming their way, because their new Republican governors fear their budgets will eventually be saddled with burdensome maintenance costs even if states are not asked to help pay to construction costs.

Beyond questions about funding, the rail project is running headlong into the oldest and biggest criticism about federal investment in innovative technologies: The government has no business picking winners and losers — which in this case means rewarding only part of the country with a potential economic development bonanza, and by using billions in tax dollars from parts of the country that would remain just as reliant on the car as always. This ideological difference with the president has taken on a sharply partisan tone; critics of the high-speed system are deriding it as “Obamarail” — a conscious echo of the pejorative “Obamacare” that conservatives use to describe the health care overhaul.

A Souped-Up GPS

Today’s air traffic control system basically relies on the same technology that has been in place since the 1930s. Planes still navigate with radio beacons and report their positions to human beings, who track aircraft positions through radar signals that degrade over long distances. Because of the way radar technology works, controllers receive position updates only about once every 4.5 seconds. That may not sound like a paucity in data collection to people traveling at land speeds, but a modern jet can fly nearly a mile during one sweep around the radar circle.

Because of this, the FAA has to build in significant buffer zones — typically about 5 miles of minimum spacing between planes in all directions. Planes also have to be “handed off” between regional control centers as they fly through segments of the system.

NextGen’s goal is to change this inefficient process by replacing radar stations with satellite technology that functions like a souped-up GPS. It would allow controllers real-time access to plane positions, and would also allow all pilots to view their own positions relative to all the other planes nearby. All of this means planes would be able to fly straighter routes with less buffer spacing, less fuel burned and fewer delays.

The FAA envisions NextGen being fully deployed by 2025, although most of its effort in recent years has been on the midterm goals set for 2018.

But the persistent criticism dogging the system has been that people aren’t quite sure whether the FAA will be able to pull it off. Though NextGen as a concept was formally initiated in 2003, the agency has been engaged in various “air traffic control modernization” efforts for several decades.

And, the FAA has repeatedly stumbled in those past efforts; an attempt to upgrade control towers and navigation systems two decades ago led to $1.5 billion in overruns and prompted President Bill Clinton to suggest creating a public corporation to run the air traffic system.

From 1995 through 2009, the Government Accountability Office classified air traffic modernization efforts as a “high risk” federal project. And though the GAO removed it from the list, the Transportation Department’s inspector general noted in a recent report that the FAA still isn’t doing enough to plan for the program in the long term.

“FAA has delayed critical decisions on how key NextGen capabilities will be designed and integrated,” Calvin Scovel, the Transportation Department’s inspector general, said February in a report. “Continuing to delay these decisions will slow NextGen’s overall progress.”

Scovel also noted that an analysis by the National Academy of Public Administration found that some of the new system’s capabilities that were originally supposed to be operational by 2025 may not actually come online for a decade after that — which would likely cause the costs to balloon far beyond the projected $40 billion.

The airline industry, which the government expects to bear half of the cost to equip its planes with the avionics needed to communicate with the new system, also hasn’t completely signed off on the effort.

The Air Transport Association, the trade group that represents most major U.S. airlines, says air traffic control modernization is essential. But the group argues that because they can’t be sure the FAA will follow through on its plans, the industry shouldn’t have to pay all the equipment costs associated with installing and maintaining the sophisticated avionics.

This is an additional concern now that Congress has been seized by budget-cutting fever. Originally, NextGen was to be funded by creating an entirely new revenue stream to replace the current system of excise taxes, primarily based on the price of a plane ticket. The Transportation Department under President George W. Bush pushed for replacing the tax system with a new funding stream that would be based on aircraft size and distance traveled.

But corporate jet and private plane lobbyists stopped that effort with the argument that their clients would pay disproportionately under that sort of regime. Now the Obama administration envisions a mix of dedicated tax revenue and general appropriations to finish NextGen. The airlines say they’re far from confident that the revenue will be there reliably, year after year.

Beyond that, both their trade association and the Transportation Department’s inspector general have criticized the FAA for not outlining what NextGen’s final performance capabilities will be and for not setting clear standards for measuring whether the new system really does save both the government and the airlines time and money.

High-Speed Dreams

The administration’s plans to bring high-speed rail service within reach of 80 percent of Americans is no less ambitious in its scope, but is arguably even more fraught with uncertainty than the air traffic control plan.

Obama’s six-year, $53 billion budget for the idea would be only the first installment in a 25-year quest to give a majority of Americans access to what for most people would be a completely new travel alternative to airlines and automobiles. The high-speed rail initiative is described at the Transportation Department as a “signature program,” and the administration clearly intends for it to be Obama’s transportation legacy, a transformational program inseparably linked with his presidency, just as Dwight D. Eisenhower is associated with the Interstate Highway System.

Beyond that rhetoric, the administration also argues this new travel option would be more fuel-efficient and therefore more environmentally friendly, and that its “Buy American” requirements would revitalize the U.S. manufacturing sector and create a raft of new jobs that couldn’t be outsourced.

“Part of making our transportation sector cleaner and more efficient involves offering all Americans — whether they are urban, suburban, or rural — the choice to be mobile without having to get in a car and pay for gas,” the president said in a speech last month.

But the administration has yet to provide any ideas about how this massive investment would be funded. In the current climate of fiscal austerity, it’s no surprise a proposal to dedicate so many billions on an idea without a proven track record has been embraced by relatively few lawmakers, almost none of them Republicans.

A “shocking waste of money,” says freshman GOP Sen. Pat Toomey of Pennsylvania.

“Please don’t talk to me about high-speed rail. That’s hardly a solution,” said Jerry Lewis of California, a senior Republican on the House Appropriations Committee, which provided $8 billion in high-speed rail grants in the 2009 economic stimulus law and has since allocated $2.5 billion more. That was the grant money spurned by the three GOP governors, who had promised to reject it in their campaigns: John Kasich of Ohio, Scott Walker of Wisconsin and Rick Scott of Florida.

But a fellow Republican, Transportation Secretary Ray LaHood, counters that more than 30 other states have been happy to accept high-speed rail money — and that he is moving ahead with plans to reallocate the money to other states.