It´s only a my personal opinion based on what happened in Italy (so a completely different social-economic contest) but I think that carload traffic is the blood of railroad freight traffic and operators need to value very well the opportunity of loose to truckers. As Cowford told, some businesses simply don' t generate enough traffic for a block train and intermodal sometimes is not the right solution because of high tare and/or special needs for transport. But these smaller flows, if well managed, feed long distance trains between marshalling yards and, satisfying small volume clients, can generate more traffic.
The contrary of what happened in the last 30 years in Italy where the incumbent state owned operator discouraged clients closing carload points and sidings, imposing stupid conditions and avoiding to strictly control costs and tariffs. The result is that now hump and marshalling yards are closed or badly underutilized, the few Trenitalia freight trains are basically block ones and the private operators that theoretically can give a better service at a lower price due to their far higher flexibility have so much difficulties with the infrastructure manager (strictly connected with Trenitalia) for installations use that various times they had to renounce services.
On the other hand business is business but in Italy (I've not knowledge in USA) the economical convenience of trucking is partly based on the systematic infringement of laws about time of driving, speed, maximum weight, state of the vehicle etc. and the consequent risk for people due to the fault of real controls. Rail transport, being far more controlled, avoid these problems and fight road congestion and part of the pollution so there are social benefits that, in a perfect world, cannot be ignored by governors.
The various lobbies (railroad enterprises, citizens, ecologists), without thinking in public subsidies, should ask for laws that favour rail transport, especially smaller quantities, but the railroad concerns too have to watch not only to bigger clients that guarantee high gain.
Ciao
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