(CNN) -- Are proposed multibillion dollar high-speed railway projects in the United States a smart move or a huge waste of taxpayer dollars?
CNN.com users are challenging politicians, policymakers and each other about whether the Obama administration's push to build high-speed rail lines in the Midwest, West Coast and elsewhere is on the right track.
Many users want proof that high-speed rail can be a profitable, efficient job generator to help raise the sagging U.S. economy when compared with other types of transportation.
Read how federal budget cuts have slashed high-speed rail funding
Experts -- including the two most powerful congressional lawmakers on rail issues, think-tank specialists and policymakers at the Department of Transportation -- have directly responded to CNN.com user comments.
Comment: "There are NO high speed rail projects in the world that are profitable. None. They are all taxpayer/government subsidized." -- CNN.com user "aksdad"
Expert response: 'Not necessarily true'
Robert Puentes at the Brookings Institution: "The Acela Express, Amtrak's high speed rail service along the Northeast corridor, has shown a positive return from its New York-to-D.C. route."
Highways, airlines: "And it's not fair to just point the finger at high speed rail. Highways and other modes of transportation, like the airlines, are heavily subsidized, too."
Expert response: Not true
Reps. John Mica, R-Florida, chairman of the Transportation and Infrastructure Committee, and Rep. Bill Shuster, R-Pennsylvania, chairman of the Subcommittee on Railroads, Pipelines and Hazardous Materials: "While many high-speed rail systems in the world rely on a government subsidy, this in no way means that rail operations cannot be profitable.
Other nations: "Private rail operators in Great Britain, such as South West Transport and Virgin Rail, compete for franchise intercity rail service contracts and regularly generate a profit. Rail routes in Japan and France turn a profit."
Private sector: "Rather than relying on the federal government and Amtrak to operate profitable passenger rail, we must put the focus on the private sector to develop and operate self-sustaining, profitable passenger rail in parts of the country where it makes sense."
Comment: "Any rail project in the U.S. will require steel rails imported form Korea or China and train components imported from Germany. Yes, we will need a few locals to put this all together, but the primary jobs will be created overseas." -- CNN.com user "StanCalif"
Expert response: Not true
Roy Kienitz, under secretary for policy, U.S. Department of Transportation: "The High-Speed Rail Program includes strict Buy America provisions, which require steel, iron and any manufactured goods used in the program to be produced in the United States."
Examples: "Already, the steel rail for projects in Maine and Vermont are being cast at a plant in Indiana. Rehabilitation of passenger cars is underway in Delaware, Indiana and New York. And, rail sector manufacturers and suppliers are developing or expanding their operations in the U.S. to accommodate anticipated future demand."
Highways cost more?
Comment: "The cost to build highways actually exceed rail costs." -- CNN.com user "sojoweb"
Expert response: It depends
Philip Longman, senior research fellow, New America Foundation:
Terrain: "Trains can't turn corners as tightly as rubber-wheeled vehicles, and they need gentler grades than trucks or cars to maintain speed. This means that in hilly or mountainous areas, building a rail line may require more earthmoving, including tunneling, than building a highway. But this consideration doesn't apply on flatter terrain, and in almost all instances, a rail line can move as many or more people than a highway using a much narrower right-of-way. Because of this, building a rail usually involves far less condemnation of private property than building an Interstate."
Technology: "Also, advances in the use of computers to control train movements are now allowing us to run many more trains on the same track than in the past. This is further adding to the cost advantage rail. Someday we may have Interstates where computers control the flow of cars and thereby allow far more cars to operate safely and quickly without building new lanes. But while "smart highways" are still a long way off, computer control of trains is now being rapidly rolled out across the country. Some people even wonder how long we will still need engineers."
Helping mid-sized cities
Comment: "History shows that investment in infrastructure results in economic growth in the future." -- CNN.com user "thenewsjunki"
Expert response: That's true
Longman, New America Foundation: "It's true in general and particularly true of specific rail projects."
Economic connectivity: "One of the biggest and often overlooked advantages of high speed rail, and even of not-so-high-speed rail, is its ability to restore the economic promise of many mid-sized cities where airline service is no longer available or prohibitively expensive.
Fast, frequent rail passenger and package express service once provided cities like Lynchburg, Virginia, or Rockford, Illinois, with the connectivity to other markets they needed to thrive as centers of business. Now, as part of "flyover America," they struggle because getting from there to anywhere else requires long auto drives to distant and/or poorly served airports ...
Comment: "You know that these projects (like high-speed rail) never end at or under budget." -- CNN.com user "rothana"
Expert response: 'Not true'
Puentes at the Brookings Institution: "It's not true to say these projects are always over budget since we have no high speed rail in the country currently."
Stimulus package: "Things are different today. The federal government's stimulus package places a tremendous emphasis on making sure every dollar was spent in a transparent way. This kind of transparency is very helpful to prevent enormous overruns..."
Expert response: 'The reader is correct'
GOP Reps. Mica and Shuster: "The reader is correct -- in the past, many of America's transportation projects have run over cost and over budget."
Bureaucracy: "The reason for this can largely be found in the cumbersome manner in which federal transportation projects are advanced. The Transportation and Infrastructure Committee has received testimony that simply adding one federal dollar to a transportation project adds 14 years to the delivery time. This is unacceptable and it inflates project costs unnecessarily."
Example: "The federal government needs to learn to do more with less. ... The I-35 W bridge that collapsed over the Mississippi River in Minneapolis in 2007 was contracted to be rebuilt in just 437 days, and actually came in ahead of schedule and under budget. There is no reason we can't expedite the process for other projects around the country."
Expert response: Proper spending ensured
Under Secretary Kienitz, U.S. Department of Transportation:
Economic engines: "These projects help build the economy. According to a study by the U.S. Conference of Mayors, a high-speed rail line to Los Angeles would create as much as $7.6 billion a year in new business sales, producing up to 55,000 new jobs and $3 billion in new wages. In Chicago, high-speed rail would produce up to $6.1 billion in yearly sales, 42,000 new jobs, and $2.5 billion in new wages for workers."
Jobs: Rail versus roads
Comment: "History shows that you get more jobs and economic growth for every dollar spent on rails than you do for every dollar spent on roads or any other infrastructure project." -- CNN.com user "thenewsjunki"
Expert response: It depends
Puentes at the Brookings Institution: "This question is impossible to answer because it's hard to talk about these projects in the abstract. It matters where and how these projects are built."
Location: "For instance, if you built high speed rail in a remote place like Montana, then economically, this project may not make a lot of sense (because it's a sparsely populated state.) However, if you focus high speed rail in corridors between metropolitan areas that are economically connected, then there is no reason why it couldn't have an economic return if built correctly. For instance, Los Angeles to San Francisco is a perfect corridor for this type of project, because there is an economic connection and it's the right distance (about 380 miles) for high speed rail to be competitive with air travel."
Comment: "High-speed rail is faster, cleaner and safer than driving." -- CNN.com user "Orangecat46"
Expert response: I agree
Sudhir Chella Rajan, senior associate with the Tellus Institute:
Other nations: "In countries where it has been effectively implemented (e.g., China, Japan and France), average speeds above 130 mph have been achieved and at relatively low costs on a per passenger-mile basis."
Pollution: "In terms of emissions too, high-speed rail is cleaner, with carbon dioxide emissions (on a per passenger-mile basis) roughly half to a third of what is conventionally achieved by automobiles at normal load factors (passengers/vehicle or wagon)."
Safety: "The record is mixed and depends on which countries we're examining. In the United States, for instance, railroad accidents have resulted in far fewer fatalities than highway accidents on a per passenger mile basis, but that the numbers are closer in countries like India and China."
What about buses?
Comment: "There are a thousand much better, much cheaper ways to move people than rail. How about a fleet of hybrid buses running in HOV lanes with stops at the same stops that rail would have had? Move the same number of riders at a fraction of the cost and with more flexible times." -- CNN.com user "dawgdays"
Expert response: It depends
Longman at the New America Foundation: "There are certainly specific places where buses will work better than rail. These are generally where travel distances are short and there are low volumes of riders."
Efficiency: "But because of the low friction of steel wheels running on steel rails, railroads are inherently more energy efficient, less polluting, and less expensive to operate than any vehicle carrying the same load using rubber wheels."
Speed: "Railroads are also potentially much faster than buses, easily reaching speeds of 150 mph, which is particularly important for being competitive with driving for more than short distances."
Congestion: "Also, unless buses run on dedicated right of ways, they contribute to traffic congestion, and must deal with it themselves. In urban settings, they are very difficult to keep running on time because they tend to bunch up while going through congested downtown areas, so that instead of, say, one bus arriving every ten minutes, three arrive every 30 minutes."
Existing infrastructure: "Giving buses a dedicated right of way solves this problem, but once you have gone to expense of doing this, you have spent almost as much as it would cost to build a new rail line... In many parts of the country, freight rail lines already exist that have plenty of capacity to add passenger trains with only minimal extra investment."
Expert response: Trains 'more effective'
GOP Reps. Mica and Shuster: "This question raises a good point, and we believe that no one mode of transportation can meet the nation's needs in every circumstance."
Short distances: "Hybrid buses make sense in densely populated urban and suburban environments where buses can relieve highway congestion in short distances. ..."
Long distances: "For long distance travel, Americans rely on their cars and the airlines."
"This reliance has led to massive congestion along major transportation corridors like I-95 in the Northeast Corridor. Today, businesses and commuters lose $115 million each year in wasted time and fuel and spend four billion hours per year stuck in traffic. 60 percent of the urban road miles of Interstate 95 are heavily congested. 70 percent of our nation's chronically delayed flights originate in the New York-New Jersey airspace. There is simply no more effective way to alleviate congestion of our roads and airways and get people to their destinations than rail."
CNN's Thom Patterson and Katherine Dorsett contributed to this report.