Officials never know who's going to show up, or how much the lines will be affected by broken machines, long ballots or confused voters.

NPR: Questions And Answers On Voting Rules

Trams have broken down, ticket machines have had to be withdrawn and passengers have put up with delays and cancellations because of engineering problems.

BBC: New Metro tracks unveiled

The company will know when a machine has run out or broken down, when demand is greatest or least and when machines need stocking.

ECONOMIST: Reinventing Marconi