Diesel electric locomotives are somewhere on the order of 100 times the efficiency of tractor trailers, which are themselves much more efficient than cars per ton-mile. If all road transit was replaced by diesel electric trains it would cut transit emissions to almost nothing. That of course would still only eliminate a fraction of total emissions, since most emissions are not transit-based.
Diesel electric locomotives are somewhere on the order of 100 times the efficiency of tractor trailers, which are themselves much more efficient than cars per ton-mile. If all road transit was replaced by diesel electric trains it would cut transit emissions to almost nothing. That of course would still only eliminate a fraction of total emissions, since most emissions are not transit-based.