So how about the evaluation of the business case?
"the Rail Development Plan compares favourably as an investment if all the benefits are
considered more broadly and over a longer period reflecting the life of the assets and the ongoing generation of benefits"
Favourably? For starters, does this "investment" include the operating cost subsidies growing? However, more importantly, by taking a different discount rate for this project compared to others, you are no longer comparing like for like. ALL other projects need to be re-evaluated, which may STILL mean, it's a bad "investment" compared to building roads. More importantly, is it better than letting people spend their own money?
Value of time
"There is a strong case for using the same value of time for car users and PT users, particularly for rail users in peak times" Is there? Make it. Oh you don't. The reason PT users have a lower value of time is related to their average incomes, so earning capacity. You can play around with this of course, but it really only should apply to PT users who switched from cars. Oh you don't really talk about that do you?
Benefit-Cost ratio: Core Network upgrade
Here the business case shows it up for how lousy it is. We get ten benefit/cost ratios. Five based on NZTA evaluation procedures, five on ARTA's own evaluation procedure. Three under NZTA's procedures have costs higher than benefits. None of ARTA's do. ARTA's base upgrade one is a BCR of 1.5, not spectacular (and with no confidence range around it. Is this the top end or the mid range (it wont be bottom)). Then we have three of the scenarios are fictional "what if fuel went in price a lot", "increase value of time" and some new economic snakeoil called "Other economic benefits relate to CBD (agglomeration) benefits (increased productivity per employee) – residential intensification – wider effects of car use – environmental benefits of new rolling stock"
Now hold right here. Increased productivity per employee because of agglomeration in the CBD? That's a pretty bold assumption. It implies rental prices increase too, of course. It implies Auckland's CBD is more competitive (than where?). $0.5 billion over 40 years? Who believes this?
Residential intensification? Why is THAT a benefit? A benefit that people live together with less space?
Wider effects of car use? What about the BENEFITS of car use? No, that's right. You'll just count some unrecognised "costs".
Oh and environmental benefits of new rolling stock are already part of the evaluation, but let's count them again hey?
Each train trip costs in subsidy today around $7. That is what each rail commuter should be paying extra, but doesn't. That is estimated to drop to $5 by 2016 after spending over a billion on upgrading the system - for 15 million trips a year. Yep you can figure that one out yourself.
"Abandoning the rail passenger system in Auckland would require construction of new busways running parallel to the existing rail lines" In many cases it wouldn't as you could rip up lines except the main trunk to the Port. That gives you busways from Britomart to West Auckland and south to Southdown, beyond that buses can operate on local streets or join motorways and use the hard shoulder as a lane.
ARTA/ARC have dressed up the rail business case to suit the answer they wanted, on grounds that the government's own funding agency would question. It will continue to cost taxpayers $5 per trip when electrified, it will generate very modest benefits, and most of those who benefit will be those who get their trip subsidised. It will make diddly squat difference to those using the road network, at best it might increase property values for those living nearby a station and work nearby one on the same line, or businesses who may have a catchment from those able to use the train.
At best, it needs independently appraised - not by anyone in Auckland local government - to determine if the appraisal itself is robust, the levels of confidence and optimism bias around costs and benefits, and whether a thorough appraisal of alternatives has been included.
Sadly, National has been taken for a ride, and you're being asked to pay.