A few decades ago, the United States had several railroad tunnels that ranked in the top 20 longest railroad tunnels in the world. Now, unless I missed something, there are ZERO U.S. railroad tunnels among the top 190 longest railroad tunnels in the world.

Why? Because, for operation of long railroad tunnels, you need electrification. For anything over 10 miles long, forced ventilation is no longer practical. And, even for shorter tunnels, ventilation provides a major choke point, as it takes time to vent the tunnel after each train, and, in most cases, it is not practical to have more than one train in the tunnel at one time, even if they are going in the same direction.

At some point, if the U.S. wants to have world class railroad infrastructure, it is going to have to look at adding new tunnels. And for that, again, you need electrification. (Yes, individual railroads probably would not be willing to put up the money for either the new tunnels or electrification; this would have to be backed at the federal level. But, in some cases, it would make sense for two or more major railroads to get together -- with federal backing -- to jointly build some of these long tunnels.)

Many of the world's long tunnels are so-called base tunnels, below older shorter historic summit tunnels. The long tunnels not only eliminate steep climbs to reach the old summit tunnel, but can also be taken at much faster speeds due to the elimination of curves on the climb to the old summit tunnel. And, with the reduction in grades, they require far less motive power.

(In most cases, European countries have continued to keep the old routes for local service and as emergency detours when there is a problem or required major maintenance in the base tunnel. But, with decreased traffic, the old historic routes are now easier to operate and maintain.)

Just something to think about.