Interstate 5 goes many places other than just Portland and Vancouver. Of course the train can add in additional stops, reducing its speed advantage but will never be able to compete with a road in terms of destination count or the network effect. Which doesn't necessarily mean it's a bad idea, just that there needs to be enough people going between just the destinations served to compare to the number that would the additional road lane. Induced demand exists but is a sign of success of utility of the road. The comparisons even when everyone is being honest aren't all that clear cut and involve a huge number of variables. Also consider most companies that build roads can also build rail infrastructure or at least parts of it. A rail line isn't starvation for them and they would likely get a piece of that pie.