Funding asset maintenance is hard. Cities and other agencies rarely have sufficient funding, so they have to make choices about where to direct available funds. The classic approach is to fund asset maintenance according to a predetermined maintenance schedule. However, this falls apart when there isn’t enough money to complete all scheduled work.
The most common fallback has been a “worst-first” approach, where the assets that are in the worst shape are maintained. Worst-first can be quite expensive, though, because the worst assets often require costly reconstruction. This approach also overlooks the fact that some assets are more important than others, and it’s hard to predict exactly when one may fail. It may be wise to delay repairing an asset that is in poor condition, but is less consequential, when compared to an asset that is also in poor condition that is highly consequential to the health, safety, and/or welfare of the community.