This seems like a weird abdication of responsibility. Sure, the schools probably shouldn't have been built there. Let's accept the premise that was the main error. That still doesn't excuse the traffic engineers - fault is not indivisible.

You say they can't with away the people's lives. True, but they can't wish away the bad decisions made by others either. They still have a choice to make, between allowing a dangerous situation for children or a worse traffic circulation. And it's valid to judge that decision.