When you manage water pipes, gas networks, or electricity grids, two spatial analysis capabilities come up again and again: routing and flow analysis. On the surface, they might seem similar, but they answer very different questions. Understanding how they work individually—and, more importantly, how they work together—helps you get far more out of your GIS data than either technique can deliver on its own.
This article walks through both concepts from the ground up, explains where they overlap, and shows how combining them transforms raw network data into decisions you can act on.
What is routing in GIS, and how does it work? #
Routing in GIS is the process of finding a connected path through a network between two or more points. In utility and infrastructure contexts, routing does not mean finding the fastest road for a delivery van. It means tracing a logical path through a network of pipes, cables, or conduits based on how those assets are physically and topologically connected.
The foundation of routing is topology. Your GIS data needs to know which pipe segment connects to which valve, which cable runs into which junction box, and in what order those connections exist. Without that topological structure, routing simply cannot function. The system evaluates the network graph and determines which path satisfies a given set of rules—whether that means the shortest physical distance, the fewest components, or a path that avoids certain asset types.
In practice, routing answers questions like these: Which assets lie between a source and a specific delivery point? If a valve closes, which sections of the network become isolated? Which field crew needs to travel to which segment first? These are operational questions that routing answers by traversing the network logic stored in your spatial data.
What is flow analysis in GIS, and what does it measure? #
Flow analysis in GIS measures how a substance, signal, or resource moves through a network over time. Rather than simply identifying a connected path, flow analysis quantifies what travels along that path, including volume, pressure, velocity, direction, and capacity. It adds a physical or hydraulic dimension to the structural picture that routing provides.
For water utilities, flow analysis calculates how much water moves through each pipe segment under different demand scenarios. For gas networks, it models pressure distribution across the grid. For electricity providers, it tracks load distribution and identifies segments operating near their rated capacity. The inputs typically include asset attributes such as pipe diameter, material, and length, combined with demand data and source conditions.
Flow analysis also captures direction. In a gravity-fed water network, flow direction follows elevation gradients. In a pressurised gas system, it follows pressure differentials. Knowing direction matters enormously when you need to trace contamination, isolate a fault, or plan a network extension.
What is the difference between routing and flow analysis in GIS? #
The core difference between routing and flow analysis in GIS is that routing identifies which path exists through a network, while flow analysis quantifies what moves along that path and how. Routing is structural; flow analysis is physical. You need routing to define the network geometry, and you need flow analysis to understand what that geometry actually does under real operating conditions.
Think of it this way: Routing tells you that pipe A connects to pipe B, which connects to pipe C. Flow analysis tells you that, under peak demand, pipe B carries 80% of its rated capacity and pipe C is likely to experience a pressure drop. One describes connectivity; the other describes behaviour.
The two techniques also use different data inputs. Routing depends primarily on topological accuracy, meaning your network assets must be correctly connected in the GIS. Flow analysis additionally requires attribute data such as diameter, roughness coefficients, elevation, and demand figures. This means flow analysis is more data-intensive and more sensitive to data quality issues in your asset register.
How do routing and flow analysis work together in utility networks? #
Routing and flow analysis work together by combining network connectivity with physical behaviour modelling. Routing first establishes the valid paths through your network, and flow analysis then simulates how resources move along those paths. Together, they let you answer operational questions that neither technique can answer alone.
Fault isolation and impact assessment #
A common combined use case is fault isolation. When a pipe bursts or a cable fails, routing identifies which assets are directly connected to the affected segment and which isolation valves or switches can cut off that section. Flow analysis then models the downstream impact: which customers lose supply, by how much, and for how long. That combination moves you from “Where is the fault?” to “What does the fault mean for the network?”
Network planning and capacity analysis #
When planning a new connection or network extension, routing determines the feasible path from source to destination. Flow analysis then validates whether existing infrastructure can handle the additional load. Without flow analysis, you might route a connection that looks perfectly logical on the map but would cause pressure failures or overloads elsewhere in the network.
What data and tools are needed to run routing with flow analysis? #
Running routing with flow analysis requires clean topological network data, accurate asset attributes, and a GIS platform capable of handling both network traversal and spatial modelling simultaneously. The quality of your results depends directly on the quality of your input data.
On the data side, you need:
- A topologically correct network model with properly snapped nodes and connected segments
- Asset attributes including material, diameter, length, age, and condition
- Elevation or pressure data to determine flow direction
- Demand data or consumption records linked to connection points
- Source and boundary conditions such as reservoir levels or injection points
On the tooling side, your GIS platform needs to support routing and spatial analysis capabilities that go beyond simple map display. You need routing and topology capabilities built into the analysis layer, not bolted on as an afterthought. Platforms that offer native data access—meaning they query your asset data directly without requiring a separate extract—give you a significant advantage because your analysis always reflects the current state of the network. Our spatial analysis capabilities are built around exactly this kind of integrated approach, combining routing, topology, and spatial relationships in a single analytical environment.
How can combined routing and flow analysis improve infrastructure operations? #
Combining routing and flow analysis improves infrastructure operations by turning your GIS from a map viewer into a decision-support system. Instead of describing what your network looks like, you can model what your network does—and what it will do under different conditions.
Faster incident response #
When a fault occurs, field crews need to know which valves to close, which customers are affected, and which alternative supply routes are available. Combined routing and flow analysis answers all three questions in seconds rather than hours. That speed directly reduces outage duration and the operational cost of incidents.
Proactive asset management #
Flow analysis run across your routed network highlights segments that consistently operate at high capacity or experience repeated pressure anomalies. Those are your highest-priority assets for inspection or replacement. Rather than replacing assets on a fixed schedule, you replace them based on actual network behaviour, which is both more cost-effective and more operationally sound.
Regulatory reporting and compliance #
Many utility regulators require documented evidence of network performance, supply reliability, and risk management. Combined routing and flow analysis generates the underlying data for those reports automatically. You can demonstrate which areas of your network meet performance standards and which require investment, with spatial evidence to back up every claim.
At Spatial Eye, we build spatial analysis solutions that bring routing, topology, and flow modelling together in one integrated platform. If you manage utility or infrastructure networks and want to move from static mapping to active network intelligence, contact us to discuss your network and we are ready to show you what that looks like in practice.
