That's just silly. You would get into the most ridiculous moral quandaries with thinking like that. If 75,000 people commute 1 hour each day on a highway and then someone offers to reconfigure the highway to cut the time in half and all he is asking for is the lives of 100 children, its a good trade!

At an avg lifespan of 78 years, 100 kids is ~68 million hours. 30 minutes saved a day / 261 days / year for 75,000 people is ~9.7 million hours a year, so after 7 years, it basically free. Except we would never do that because we don't measure human value in hours because the people in power would be free to make some really terrible optimizations.

You are right though, you did include cancers and I ignored it so we can call it a tie.