Depends on lane, commodity carried, distance hauled and so forth. A company I worked for split some loads between truck and rail for a move of around 900 miles or thereabouts and rail was a little cheaper, but that was for a very, very heavy commodity.
Rail simply isn't set up for moving loads that cube out before maxing out the weight of a railcar. I can move, for example, a load of paper towels much cheaper by truck than rail because most rail equipment really can't carry all that much more volume of low-density product than a standard 53 foot trailer. Conversely, I can move a load of cement or sand or stone over a longer distance at a much lower rate than trucks could ever match.
Intermodal helps railroads with the cubing issue and, on certain lanes, can actually be dependable and, within reason, rather time competitive as well. If railroads would be willing to build 89 foot, high cube boxes and keep them clean and cycle them rapidly, I know of a few consumer products they could once again be competitive for.
All in all, trucks own the time-sensitive freight market. Rails own bulk commodities,
Be well. Do good work.