Five things that are barriers to "high speed" rail.
1. Its expensive. It requires a large expensive physical plant connecting "hubs". It has to actually occupy ground, which means it has to displace those occupying the ground. Maintenance of the physical plant is expensive and since it will operate at higher speeds, will require more stringent standards on the "guideway". In order to achieve the speeds required to be competitive, it would require a separate, alignment designed specifically for it that has multiple tracks. It also takes a long time to build, so the company would have to support huge expenditures up front for years before it can build any revenue stream at all.
2. Its slow. The highest "high speed rail" in the US is about 150 mph for brief stretches. Conventional, existing rail lines do not have the right of way laid out to support high enough speeds to compete with airline schedules. It would have to be able to sustain 250 mph or more to be time competitive. Most of the "time benefit" of rail now is that the airlines lose time in processing people on the ground before and after the actual flight or travel time to and from the airport. Current rail lines go into population centers. Current facilities will not support higher speeds. If the high speed terminals are built outside the city center, that will add time getting to and from the station. Longer distance travel will mean people have more luggage and so there will be the same delays at either end to check or retrieve baggage.
To do maintenance on a rail line, traffic has to be stopped while the work is performed. That forces all the traffic onto remaining tracks, severely limiting capacity on that line. The longer the routes the more chances of encountering maintenance. The longer the routes the less opportunity there is for a "window' where a train will not encounter a maintenance window.
3. It requires a supporting infrastructure. Neither airlines nor railroads actually take you from where you are to where you want to go. They operate hub to hub, and then other modes of transportation move you from your starting point to the origin hub and from the destination hub to the final destination. Currently most train stations do not have a well integrated infrastructure at either end. To be successful the trains will have to have car rental, shuttles, park and rides, etc., just as airports do.
4. It does not foster competition. Since the cost of building a system is so hugely expensive and takes a long time to do, having multiple right of ways is prohibitive. That means all the vehicles have to use the same guideway. That reduces the differentiation between vendors. You can only go as fast as the vehicle in front of you and you can only go to the locations that guideway goes in the order the guideways goes.
5. It has a low revenue stream. People have a high cost per cu. ft. or per lb. to carry. Grain you stick in a big metal box that is the size of the clearance diagram. People cannot be packed in that tight, require heat and air conditioning, soft seats, lighting, quiet, and a smooth ride. They are also very price sensitive. For a slower trip they will expect lower cost. Finding a price point that covers fixed costs and maintenance, but is competitive with air has always been a challenge. Railroads have never been able to fully recover the increased cost of accommodating passengers. They couldn't make hauling animals profitable, people is even harder. For these reasons, most if not all rail passenger service is subsidized by either freight traffic or government support. If you are making a separate high speed line, then freight traffic is pretty much off the table. That means government support.
About 20 years ago, I found an article in Railway Age that maintained that railroads would never be able to charge enough to recover the increased costs of hauling passengers. The article was in the "100 years ago" column and was a reprint of an article from the late 1890's or early 1900's. This is not a new discussion.
