Bond projects replace and reconstruct streets and utility infrastructure. The Street Maintenance Fee is designed to proactively maintain streets that are maintainable.
An analogy to think of would be: "Think of Bond projects like replacing the Engine in your car. Expensive, but when you have to, you have to. Think of the Street Maintenance Fee like Changing the Oil in your car. If you are consistent and have the budget for it, you extend the life of your engine exponentially."