Rebuilding Barcelona’s TCO – and Correcting the Split

Ada re-derives this chapter’s own numbers step by step, at full precision

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Rebuilding Barcelona's TCO -- and Correcting the Split

Barcelona’s five-year total cost of ownership for 3,800 smart-parking sensors comes to $2,699,700, or $710 per sensor — a figure the audit reproduces line by line. But the chapter then reads that total as “38% initial investment, 62% ongoing,” a split the numbers underneath it do not support. So does the 38/62 split actually match the line items, or has it been inverted?

Companion to the chapter Lessons from Real Deployments — every number here comes from that chapter.

Ada: The Barcelona five-year total-cost-of-ownership example lands on $2,699,700, and I can reproduce that exactly from its line items. But the sentence that interprets it – “38% initial investment, 62% ongoing” – does not match the numbers it describes, so I will rebuild the whole thing and correct the split.

  • Year 0: 3,800 x 250 + 3,800 x 2 x 50 + 19 x 2,000 + 150,000 = 950,000 + 380,000 + 38,000 + 150,000 = 1,518,000.
  • Annual operating: 15,200 + 6,840 + 22,800 + 25,000 + 65,000 = 134,840; annual hidden: 66,500 + 5,000 + 12,000 + 18,000 = 101,500; combined 236,340 per year.
  • Five-year TCO: 1,518,000 + 236,340 x 5 = 1,518,000 + 1,181,700 = 2,699,700, i.e. 2,699,700 / 3,800 = 710 per sensor. Both match the chapter.
  • The split, though: initial is 1,518,000 / 2,699,700 = 56.2% and the five years of operating-plus-hidden are 1,181,700 / 2,699,700 = 43.8%.

So the chapter’s “38% initial / 62% ongoing” is inverted – initial cost is actually the larger share here, about 56%, a correction the page’s own calculator confirms when it reports operating at 44% of TCO. The design meaning survives the fix but shifts emphasis: over a five-year horizon this deployment splits roughly 56/44, so a budget that under-provisions the recurring ~$236k/year still under-funds nearly half the lifetime cost – exactly the “run out of funding in Year 2-3” trap the chapter warns about.

Every number above is taken from the chapter’s own material and re-derived step by step.