Isochron (Drive-Time Rings)
See how far you can travel from a point within a set time or distance.
An isochron — also called a drive-time ring — shades the area you can reach from a chosen point within a given number of minutes, or within a given distance in metres. It is useful for planning response zones, picking a staging area, and showing a crew how long they are really from a location. You drop a pin on the map, choose how you are travelling and how far, and the app shades the reachable area.
Overview
The isochron popup is a small card with three drop-down selectors and two buttons.
| Control | What it is | Default |
|---|---|---|
| Routing Profile | How travel is measured | Driving-traffic |
| Contour Type | Whether the reach is a time or a distance | Minutes |
| Contour | How far the reach goes | 10 min |
| Save | Draw the area on the map | — |
| Back | Close the card and change nothing | — |
Routing Profile
| Choice | What it means |
|---|---|
| Driving | Road speeds, ignoring current traffic. |
| Driving-traffic | Road speeds adjusted for traffic right now. This is the default. |
| Walking | On foot, using paths and pavements. |
| Cycling | By bicycle, using cycle-friendly routing. |
Contour Type and Contour
The values offered in the Contour selector change to match the Contour Type you picked.
| Contour Type | Contour choices |
|---|---|
| Minutes | 10 min, 20 min, 30 min, 40 min, 50 min, 60 min |
| Meters | 1000 meters, 5000 meters, 20000 meters |
The card opens with Driving-traffic, Minutes and 10 min already filled in, so you can tap Save straight away for a ten-minute drive-time ring.
Getting Here
- From Home, open References, then open the Map reference. (The isochron tool also appears on an open saved map.)
- Tap the menu button in the top corner to open the map options.
- Tap Add Isochrone. The menu closes and a short message appears: Tap on map to select a location.
- Tap the spot you want to measure from. A pin drops there and the isochron card opens on top of the map.
Add Isochrone is drawn faintly and does nothing when you have no internet connection. Drive-time areas are calculated on the server, so this tool cannot be used offline.
Draw a Drive-Time Ring
- Tap Routing Profile and choose Driving, Driving-traffic, Walking or Cycling.
- Tap Contour Type and choose Minutes for a travel time or Meters for a distance.
- Tap Contour and pick the value. If you change the contour type afterwards, open Contour again — the list has changed and your earlier pick may no longer make sense.
- Tap Save. The card closes, the app fetches the area, and the reachable region is shaded on the map in translucent red with a solid red outline. The pin used to place it is removed once the area is drawn.
To try a different reach, repeat the steps. The new area replaces the old one — you will never end up with two rings stacked on top of each other.
If a selector is left showing the placeholder text Select, saving is blocked and you will see Select Routing Profile, Select Countour Type, or Select Countour. Tap OK on the message, make a choice in that selector, then tap Save again.
Switch Contour Type to Meters when you care about straight reach distance rather than how long the drive takes — for example when setting a hazard stand-off or a canvass radius.
Clear a Drive-Time Ring
The shaded area stays on the map while you keep working. To remove it, open the map menu and tap Current Location, which clears everything drawn on the map and re-centers on you. Leaving the map screen also clears it.
How This Connects
- The reachable area is calculated on the server from live road data each time you tap Save, so the same pin and the same settings can give a slightly different shape at a different time of day when you use Driving-traffic.
- The ring is drawn on top of whatever base map and layers you already have. Change them from Base Map and Map Layers in the same menu, or from Map Style Options.
- A drive-time area is a temporary drawing. It is not saved with a saved map and it is not shared with your team. To leave something behind for other people, place a marker or a shape instead — see Add Objects to a Saved Map.
- For a point-to-point figure rather than an area, use the Bearing and Distance tools on the same menu. See Bearing & Distance.
- Drive-time thinking pairs well with the route you will actually take. Set that up in Directions, where you can also restrict the route by apparatus height, width and weight.
Troubleshooting
| If this happens | What to do |
|---|---|
| Add Isochrone looks faded and does not respond | You are offline. Get back on a connection and try again — this tool cannot be calculated on the device. |
| You tapped Add Isochrone but no card appeared | The card only opens after you tap a point on the map. Watch for the Tap on map to select a location message, then tap the map. |
| Save shows Select Routing Profile / Select Countour Type / Select Countour | One selector is still on its placeholder. Open that selector, pick a value, and save again. |
| The spinner runs but no area is drawn | The server returned nothing usable for that point — common far out at sea or deep in wilderness with no road network. Try a point nearer a road, or switch Routing Profile to Walking. |
| The area looks far too small or too large | Check Contour Type. A contour of 1000 in Meters is one kilometre of reach, while 10 in Minutes can be many kilometres by road. |
| The ring disappeared | Any use of Current Location, or leaving the map screen, clears temporary drawings. Draw it again. |
Related Pages
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