Picklu san., why put me in pickle? I can only do thumb-rule calculations and have tendencies to add zeroes or eat up zeroes., but yes the reason I did was to point out that the cost on paper looks big but in reality it is *peanuts* for the infrastructure you are getting.
And it was to score the point that this infrastructure was needed day-before-yesterday and not day-after-tomorrow. I have been on that sector and have banged my head several times. If at all somebody asks me that was a dropped as a baby to behave the way I sometimes do - my answer is no. I am what I am because of my commute on that sector.

*IT IS DEFINITELY NOT FOR THE FAINT OF THE HEART* - the overcrowding is daily and the roads are not safe (seen several blood curdling accidents).
Anyway, coming to the numbers., let us go with your numbers (I will pull your numbers below):
1. If we run at peak capacity 24 hours a day and load 1500 passengers in each train, we get ~ 950k passengers per day
Total number of passengers per day - 950000 (1500 * 13 trains per hour * 24 hours * 2)
Let me cut it down - since the passengers will not pay for return ticket., ticket is one way. Also let the average be 10 trains per hour and operating only 20 hours and the total number of passengers per train is 1500.
So (my new calc)., 1500 * 10 * 20 = 300000 (or 300 k). (1/3rd reduction).
2. Let us say ticket price per today's rate will be Rs. 2625.
So revenue per day = 2625 * 3000 = 787500000 = 7875 lakhs or 78.75 crore Rs. (daily)
3. In one year revenue (just by train tickets) = 78.75 x 30 x 12 (30 days in a month, 12 months in a year) = 28,350 crores
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Let us round it off to 28000 crore per year revenue from ticket sales alone.
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Assuming 98% Operating expenses (that is debt servicing* + salaries + electricity + everything else) (NOTE: Indian railways currently has operating expense of 98%., so it is doable for HSR as well)., then the total remaining after expenses will be
28000 * 0.02 = 567 crores.
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*Debt Servicing: The total cost of the project is 89k crores., let me inflate it to 100k crores (12k crores for interest at 0.1% p.a and any cost inflation)., then average amortization is 2k crore per year for 50 years.
That is once the foundation is laid., one has to pay 2k crore for 50 years.
You see the 0.1% interest is the real kicker. Per my calculation over *50 year* term is 3200 crore.
Hence the "debt servicing of interest" here is 3200 crore over 50 years or 64 crore per year.
The principal+interest payment is 2k crore per year.
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How much is interest of 64 crore on a revenue of 28000 crore?
0.0025%
^^ You must realize that 0.0025% is a rounding error! In effect you are paying off the principal only. Agreed that your principal component is @8%., so if your operating expense is 90% (very much doable)., then you are free and clear with a decent profit.
Now coming to your statement:
Again, assuming 5% available for debt service makes it 4500 crore per year hence the project budget better not to overshoot beyond 225k crore (230%, not unheard off in Indian Infra projects) because then even the crush load will not be able to recover the debt burden even at 0.1% rate and 50 years term.
What you are pointing out is that if the project budget over shoots., then the rosiest of the calculation goes awry. Of course., it is like me building a home to rent out and I overshoot my budget by 200%. Of course all my calculations will go for a toss.
In effect, what I hear is that the only way we come out on top is to keep within budget.
And that is what Suraj san is saying., that project delays cause overshoot of budget. In this case instead of fighting against the project, we must quickly implement the project. The faster it reaches the peak load, the better it is for all of us.
Now we are not talking about just the Mumbai-Ahmedabad sector. If I were to dream., I would extend this HSR as follows:
1. Mumbai-Surat-Baroda-Ahmedabad-Jaipur
2. Baroda-Ratlam-Kota-Mathura-Delhi
3. Jaipur-Delhi-Agra
4. Agra-Kanpur-Lucknow-Varanasi
And that too in the next 15 years. A person sitting in Mumbai, reaches Baroda in 1 hr, Delhi in 5 hrs and to Varanasi in 7 hrs. So take the last train to Varanasi and arrive in the morning next day
How much will the ridership will be? 4-5 million a year on the above sectors.