Timber Transport in the 21st Century

Last Thursday on I-77 near Chesapeake, I passed a truck carrying a load of logs. The development of the modern truck for transport of large, cumbersome items changed the face of mass transport for the United States. Trucks are primarily utilized for commodity goods for end user consumption, but are also used for movement of raw materials such as coal or wood. Intricate supply systems are now in place for rapid fulfillment of orders as needed to lower overhead costs for companies.
According to a 2007 study from the University of Memphis, 4%, in tons, of freight moved by truck was a wood product. While this number is low, the flexibility of trucks creates opportunities that are much more difficult via railroad. The numbers change when examining revenues for truck versus rail transport. 27% of all revenue for railroads is generated by wood, paper, and associated products. That translates to $2.70 out of every $10 is directly impacted by timber or wood products.
Looking at this data, how does revenue show the impact of timber on railroads? Why would this information be relevant when maintaining rail lines or building new ones?

Report retrieved from: http://www.memphis.edu/ifti/pdfs/cifts_freight_baseline.pdf