School buses are extremely expensive, and represent a huge investment for any school district which has purchased a fleet. It's entirely understandable that a district would want to get the most possible use out of their buses. However, nothing escapes the ravages of time, and at some point any school bus will outlive its usefulness.
Pitching a major fleet upgrade can be an uphill battle, but sometimes it's simply necessary. Or, at least, the cost-benefit analysis points towards old buses being too much of a liability. Here are some big warning signs that those older buses should probably be replaced.