GIS data quality becomes a life-safety issue under NG911

June 3, 2026 · 2 min read · HQT

Legacy 911 routes calls using tables that map phone numbers and cell sectors to answering points. Next Generation 911 routes calls using the caller's location against GIS layers: road centerlines, address points, and service boundaries. If those layers are wrong, calls can be misrouted. GIS data that was fine for planning maps is now safety-critical.

What the data must do

• Address points must exist for every addressable location and be positioned accurately
• Road centerlines must have correct names, ranges, and topology
• Emergency service boundaries must be seamless with no gaps or overlaps
• Boundaries between neighboring answering points must agree with the neighbors' data
• Everything must be maintained as new construction and annexations happen

Where agencies usually stand

Address data lives in several places: the assessor, the planning department, the utility, the dispatch center. They disagree. Boundaries were digitized years ago from paper. Nobody has compared their data to the neighboring county's.

What the work looks like

1. Assess the current layers against the applicable NG911 GIS data standards.
2. Reconcile addresses across sources and establish one authoritative address point layer.
3. Fix topology and attribute errors in centerlines.
4. Coordinate boundary agreement with neighbors and the state 911 authority.
5. Build validation tooling and a maintenance workflow so quality holds.

Why we write about it

This is software and data work as much as it is GIS work. Validation rules, reconciliation pipelines, and change workflows are what keep the data right after the initial cleanup, and they are the part most often left undone.