Wouldn't it be faster for the autonomous trucks to go on autonomous trains in-between major hubs then drive off to do the last mile? Might require a built up o

Wouldn't it be faster for the autonomous trucks to go on autonomous trains in-between major hubs then drive off to do the last mile? Might require a built up of rail infrastructure and I don't know the limits of freight trains in general, but seeing passenger trains, going 2-3x faster than road speed limits I reckon while maybe not by as much, freight trains could still go quite a bit faster than driving the trucks long distances.