Farm track and driveway route planner by gradient

Who uses this

• Farmers and foresters. Sketch a track line that machinery can use.
• Lifestyle-block owners. Test whether a driveway to the house site can make the grade.

When to use it

• Sketching where a farm track, a driveway or a walking track could go on a hillside.
• Checking whether a grade limit can be met at all between two points.
• Guiding the route past places it has to reach, such as a gate, a house site or a stream crossing, by adding them as stops.

Which tool for your job

Route Explorer is one step in a bigger question. These are the jobs it helps with, and the tools that go with it.

How to use it

1. Open Route Explorer and tap the start. Tap any stops the route must pass, in order, then the finish: up to 10 points in all. Undo point removes the last one.
2. Set the maximum route grade in percent.
3. Tap Finish route and run. Two versions are drawn: the smoothed route in blue and the original grid path in grey. The panel compares their length, climb and steepest grade, and the chart shows both.
4. Choose Smoothed or Original grid path. The one you choose is drawn in blue, is the solid line on the chart, and is the one the downloads contain. Hover or drag along the chart, or along the route on the map, to read each point.
5. With a pass, download the chosen route as 3D GeoJSON or KML (WGS84) or a 3D DXF polyline (NZTM2000), and its profile as CSV with coordinates. Each file name and its notes say which version it is. Saving a picture of the chart is free.

Step by step: Mt Iron, Wānaka

We ask for a track from the foot of Mt Iron to the top that never goes steeper than 20 %.

What it showed

• Lower the grade limit and the route gets longer. If no route fits, the panel says so: raise the limit or move the points.
• Choose Smoothed or Original grid path. The one you choose is drawn in blue, charted solid and downloaded; the file name says which.
• Drag along the chart and a marker follows the route on the map, with the gradient at each point.

Screenshots from NZ Elevation Tools. Aerial imagery from LINZ Basemaps. Sourced from the LINZ Data Service and licensed by Environment Southland, Otago Regional Council and Queenstown-Lakes District Council for re-use under the Creative Commons Attribution 4.0 International licence.

How it works

Terrain is loaded for all the route points plus a 500 m margin. Every cell is a node connected to its eight neighbours, with a cost that grows with distance and with grade. A step between cells steeper than your limit is not allowed. The lowest-cost path is found from the start to the first stop, then from each stop to the next, and the legs are joined into one route. That is why the route zig-zags up a face rather than going straight. This is the original grid path: a staircase of steps between cell centres.

The smoothed route pulls that staircase straight. From each corner, a straight line is run as far along the grid path as it can go while staying within 10 m of it (1.5 cells on the coarser grid of a long route), so the cell-to-cell zig-zag goes but the switchbacks stay. A straight line can end at a stop but never cut past one, so the smoothed route passes through every stop too. Heights are read from the terrain every half cell along the line, and it is kept only if it crosses no missing data and neither any 10 m of it nor any one cell length is steeper than your limit, the same step rule the grid path follows. Where no straight line passes, the grid steps stay. So the smoothed route is shorter or the same length and never steeper than your limit, though a straight stretch can be steeper than the grid path was at that spot.

Reading the results

Both versions are measured the same way. The maximum grade is the steepest over any 10 m of horizontal distance along the route, so a single noisy cell does not count as a pinch. Neither version goes over your limit, over 10 m or over one cell length; if no route fits within the margin, the panel says so instead, and with stops it says which leg failed.

The gradient shown as you move along the chart, and the gradient column in the CSV, is the rise over one cell length centred on that point, so it reads the same rule the route was built to.

Length and total climb are along the route, not the straight line. Ascent and descent ignore ups and downs of less than 2 m, the same as Elevation Profile.

The panel says how many stretches of the smoothed route stayed on the grid path because a straight line there would have been steeper.

Limits and warnings

• A terrain exploration aid, not a road design. No cut and fill, drainage, culverts, sight distances or legal access are considered.
• The search is limited to 500 m either side of the route points, so a route that needs a wide detour will not be found. Adding a stop on the detour widens the search there.
• Stops are visited in the order you tap them. The route does not reorder them for you.
• Where 1 m LiDAR has not been flown, the LINZ elevation tiles hold the national 8 m elevation model instead. It was interpolated from 20 m map contours and is not fit for site-scale decisions. The on-map result does not say which one it read: Data Here shows whether LiDAR covers a spot.

Compare quotes without ringing around

Route Explorer gives you a fast, indicative answer. When the job needs pricing, designing or signing off, getting quotes usually means calling around and explaining the same site over and over. Instead, run the tool on your site and choose Compare quotes under the result. Describe the job once and we’ll send it to up to 3 local earthworks contractors, with an aerial map of the site, a Google Earth file and your results attached, so they can price it properly from the start. They quote you directly. It’s free and there’s no obligation.

Data and attribution

Heights come from the LINZ elevation tiles: LINZ’s national bare-earth elevation model (LiDAR where it has been flown, the 8 m model elsewhere), stored in 0.1 m steps, read in your browser over the route points plus a 500 m margin, in a smaller grid than most tools: cells of about 2 m when the route points are within about 500 m of each other north–south and east–west, about 3.5 m or coarser for a longer route. Over the sea the tiles read 0 m; they hold no seabed.

Elevation and cadastral data is sourced from the LINZ Data Service and licensed for re-use under the Creative Commons Attribution 4.0 International licence. Copyright in each LiDAR survey belongs to the body that commissioned it — a regional or district council, Waka Kotahi, NIWA and around thirty others — rather than to LINZ, which hosts and processes the national dataset. Every file exported from this site names the licensors whose surveys cover the area, and anything you publish from those files carries the same attribution requirement. See https://www.linz.govt.nz/products-services/data/licensing-and-using-data/attributing-elevation-or-aerial-imagery-data

Questions

Related

Neighbouring tools

• Elevation Profile — Produces a cross-section of the ground along any line, with distance, total climb and descent, and gradient.
• Slope & Aspect — Maps how steep every part of your area is and which compass direction each face points, with a full breakdown of slope classes and aspect shares.
• Measure — Measures the length of a line you tap out on the map, corner by corner, as a flat map distance.