This idea has been adopted to some degree. The Brightline West high-speed rail project (in construction since 2024, planned to open 2028) connecting Las Vegas with Los Angeles uses existing land along the existing I-15 expressway, which is extremely congested.

I believe it was during the presidency of Ronald Reagan that private rail operators were relieved of service requirements for passenger trains, as long as the companies maintained the tracks and gave priority to passenger trains operated by Amtrak, the American state rail operator.

The companies have completely neglected the tracks and many are in poor condition from heavy use by freight trains, and as a result, maximum speeds have been drastically lowered to maintain a level of safety. Many ordinary trains in the US run at around 80-90 km/h, which is miserably slow.

In addition, Amtrak trains are supposed to be able to overtake slower freight trains by using splits in the track (where a section of track splits into two temporarily, the slower train taking one side and the faster train taking the other to pass it). However, as freight rail operators have realised, the number of engineers and conductors needed to run the trains is directly proportional to the number of locomotives, and thus they prefer running fewer, longer, trains than many shorter ones. As a result, freight trains are unbelievably long, some are a good few kilometres in length, which is longer than the entire sections of split track, making such sections worthless as it is impossible to use them to bypass the slower trains.

Where Amtrak has complete control of the tracks, such as in the northeast, service is comparable to European rail providers. For example the Acela service, which runs between Washington (DC) and Boston with stops at Baltimore, New York City, and Philadelphia. There are 20 trains per day and it reaches a top speed of around 250 km/h. The total journey takes 6.75 hours and travels 735 km (12 stops) meaning the average speed is a comfortable 109 km/h.