I agree the other benefits justify it independent of the CO2 picture. But given the headline, the cost effectiveness wrt CO2 would be a good perspective to have

I agree the other benefits justify it independent of the CO2 picture. But given the headline, the cost effectiveness wrt CO2 would be a good perspective to have as well, and to evaluate this aspect you can just divide it like that. Trains are so fixed cost heavy that I think it would always be worth it to price them for maximum utilization of capacity. It probably makes sense to subsidize them this way for that reason. The marginal cost of more passangers is so small.