Understanding changes to the underlying network – How network changes affect saved routes and what prompts appear when a route needs updating
What this guide does
This guide explains how changes to the underlying access network can affect saved routes in the National Network Map (NNM) Route Planner. This guide describes how the system highlights changes that impact a route. This guide also helps road managers understand why routes may need to be reviewed after network updates.
Prerequisites
A web browser with internet access.
Access to the National Network Map and the Routes tab.
One or more saved routes with Route IDs.
Date of last review
Date of last review: [04 03 2026]
Step-by-step instructions
Open the National Network Map and go to the Routes tab.
Select a saved route from the left-hand column or load it using the Route ID (see the “Loading an existing route” guide).
When the route loads, check for any notifications or prompts indicating that the underlying network has changed.
Review the route line on the map and any highlighted segments that show where network changes have occurred since the route was last saved.
Use Directions to open the turn-by-turn instructions and look for notes about changed segments or updated infrastructure along the route.
Decide whether the route is still acceptable or whether it must be altered due to changes (for example new restrictions or removed access).
If necessary, adjust waypoints or create a new route that complies with current network access, then save the updated route to generate a new Route ID.
Tips and common issues
Each time you open a route, the system checks it against the current underlying network and flags any impacts.
Network changes may mean that permits are now required for parts of a previously compliant route, review access and permit requirements accordingly.
For critical freight corridors, set up an internal process to review saved routes regularly after major network updates.
Where to get help
Work with your internal access or engineering team to interpret the impact of network changes on your key routes.
Contact the NHVR Route Planner or Network Management support teams if route change prompts are unclear or appear incorrect.
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