Network Condition Index (NCI)
Network Condition Index (NCI) is a length-weighted roll-up of 0-100 condition scores across all features in an infrastructure network - such as a water distribution or sanitary sewer system - giving you one comparable health score per network. Because longer features carry proportionally more weight, NCI reflects the true condition of the network rather than treating a short stub the same as a major trunk main.
Key Points
- NCI rolls up individual 0-100 feature condition scores into one network-level health score
- Each feature is weighted by its length, so big mains and roads dominate the result
- Nodes (manholes, valves, hydrants) typically carry a nominal weight rather than a length
- NCI is calculated per network - a water distribution system and a sewer system each get their own
- Tracking NCI over time supports council reporting and capital planning decisions
Formula
Example
Scenario: A water network contains an 800 m trunk main scoring 34 and a 245 m collector scoring 81.
Result: The length-weighted NCI is about 45, versus a simple average of 57.5. The failing trunk main dominates because it represents most of the pipe in the ground - which is exactly why length-weighting matters for prioritizing capital work.
Why Length-Weighting Matters
A simple average treats a 5 m hydrant lead and a 2 km trunk main as equals. That hides risk: a network full of short healthy stubs and one long failing main can look fine on a simple average while the asset most expensive to replace is quietly falling apart. Length-weighting ties each condition score to how much infrastructure it represents, so the NCI reflects where the money and the risk actually sit. Large failing mains pull the index down, which is the behaviour you want when prioritizing capital renewal.
NCI vs FCI
NCI and Facility Condition Index (FCI) are complementary, not competing. FCI measures buildings and facilities as a ratio of deferred maintenance to replacement value. NCI measures linear networks - pipes, roads, cables - as a length-weighted condition score. A municipality needs both: FCI for its recreation centres and fire halls, NCI for its watermains and roads. AssetLab feeds both indices from the same condition data, so you get one consistent picture across buildings and infrastructure.
Tracking NCI Trends
The real value of NCI comes from watching it move. AssetLab captures an NCI trend point automatically whenever new inspections update feature conditions, so you can show council a multi-year line for each network rather than a single snapshot. A flat or rising NCI shows renewal is keeping pace; a falling NCI is an early warning that the capital program is not keeping up with deterioration. Those trends turn condition data into a defensible case for infrastructure funding.
Track Network Condition with AssetLab
AssetLab provides the tools you need to put these concepts into practice with Canadian data residency and CAD pricing.