Building a City-Scale Operational Digital Twin for Real-Time Infrastructure Management
NexTech delivered an integrated urban digital twin covering 847 km of road network, 23,000 streetlights, and real-time traffic signal coordination.
A Smart City Mission-designated city needed to move from siloed departmental dashboards to an integrated operational picture of city infrastructure. Traffic management, streetlight operations, solid waste tracking, and utility monitoring were each managed by separate departments using incompatible software platforms. Emergency response coordination was entirely manual. The city had invested in sensors and cameras but had no integration layer to make the data actionable.
NexTech designed and deployed an urban digital twin platform built on open-source foundations — Apache Kafka for data streaming, PostGIS for spatial data, and a Cesium-based 3D visualization layer accessible via standard web browsers. We integrated 47 data sources across six municipal departments, normalizing data formats and building real-time pipelines for traffic signal state, streetlight status, solid waste vehicle GPS, and utility fault alerts.
The Integration Architecture
The foundational technical challenge was not visualization — it was integration. Each of the 47 data sources used different protocols, update frequencies, data formats, and authentication methods. Traffic signals used NTCIP (National Transportation Communications for ITS Protocol). Streetlight controllers used DALI. Utility SCADA systems used Modbus over proprietary VPNs. GPS trackers used MQTT over cellular.
NexTech built a normalized integration layer using Apache Kafka as the message bus, with custom connector plugins for each source protocol. All incoming data is transformed to a common JSON schema with a spatial reference (latitude/longitude or asset ID that maps to a GIS record) before entering the processing pipeline.
Governance Before Technology
One of the most critical early deliverables was not code — it was the Data Governance Framework. The city administration needed clear answers to: who has read access to which data streams, who can issue commands through the twin (such as adjusting a traffic signal timing plan), how long is location data from city vehicles retained, and what happens to the platform if the implementing vendor's contract ends?
NexTech's open-source stack directly addressed the vendor lock-in question — the city's IT department can operate and extend the platform independently. All data stays on government-controlled servers. The entire codebase was handed over with full documentation.
Emergency Response Coordination
The use case that generated the most visible impact was emergency response coordination. The twin provides the control room with a single screen showing incident location, nearest available emergency vehicles, recommended routing considering real-time traffic signal states, and estimated arrival time. Dispatchers can pre-clear signal corridors for ambulances — holding cross-traffic on green approaches until the ambulance passes. This capability reduced average emergency response time by 22% in the first six months of operation.