Design a ditch with Slope-IQ

Every part of the Slope-IQ™ Design window: BestFit, Guided and Freeform, the outlet button, each number box, the design strip, over-max shading, the fixed outlet depth with Suggest and transition, and how to make good design choices for new ditches and cleanouts.

Full Automation Kit
Guidance Only Kit
Ditch Assist Lite

In the app Survey sidebar › Slope-IQ

Slope-IQ™ turns your survey into a target grade. The default, BestFit, designs it for you: a line that falls toward the outlet the whole way, never flatter than the minimum grade, cutting as little as it can. Most ditches go from survey to grading without changing a thing. This page explains every control, so you know what to change when the line doesn't suit the job.

BestFit draws the line for you; Guided bends it through points you tap; Freeform follows your taps.

Before you start

You've surveyed the route and saved the survey (Survey a route)
The Slope-IQ Design window is open (Open the window, below)

Time: a minute or two to check a BestFit design. Drawing your own line in Guided or Freeform takes a few minutes more.

Open the window

In Ditching the window opens by itself after you save a survey and finish the 3-step setup (Ditching: design the ditch). It also opens from Edit Design on the Grade screen and from Edit on a saved design in the Load list (Edit the design mid-job). Any other time:

Tap Slope-IQ

On the Survey screen, with your survey loaded, Slope-IQ is the big white button with a zigzag line in the column of buttons down the right side of the screen. Tap it. The Slope-IQ Design window fills the screen.
1. Slope-IQ. In the right-hand column, under the survey's name.
If a design is already loaded, a window called Replace Current Design? asks first. The saved design stays on the tablet either way.

The window at a glance

Across the top: the three ways to design (tabs on the left) and two outlet buttons (right). Under them: the chart, six number boxes, and a strip of results. The boxes and the strip are shown close up further down.

Slope-IQ Design window on the BestFit tab: BestFit, Guided and Freeform tabs at the top left; OUTLET DEPTH: OFF and Outlet: Auto buttons at the top right; a chart of the ground, design and cut; six number boxes; a results strip; Cancel and Implement Slope at the bottom — **BestFit, Guided, Freeform.** Automatic, you pick the points, or you draw the line.

**OUTLET DEPTH and Outlet.** Pin the outlet at a set depth (BestFit only). Flip which end the water leaves.

On the chart, the dashed green line is your ground and the orange line is the design. Hatched tan is cut, blue is fill, dark red is cut deeper than your Max Depth (Over Max).

Everything recalculates the moment you change it. Nothing is saved until you tap Implement Slope (bottom right). Cancel (bottom left) leaves without changes.

Choose a method

Method	What it does	Use it when
BestFit	Designs the line for you. Follows the ground down where it falls fast enough, and cuts through rises and flat stretches at the minimum grade. It never designs above the ground.	Almost always. Start here on every job.
Guided	You tap survey points as control points. Straight grade lines join them, never flatter than Min Grade.	You want a straighter ditch than BestFit: bridge a low spot instead of following it down, or hold the line at a culvert or tile inlet.
Freeform	You place, drag and remove points anywhere. No grade rules at all.	You already know the line you want. The app won't stop you designing an uphill stretch, so check every segment grade.

How BestFit designs the ditch

BestFit starts at the inlet, at the ground (less any Depth Offset), and walks toward the outlet one survey point at a time. At each point it takes whichever is lower: the ground there, or the line carried on from the last point at the minimum grade. So where the ground falls faster than the minimum grade the design follows it down; where the ground flattens or rises, the design carries on at minimum grade and you cut.

That gives the least cut that still drains, and because the design never goes above the ground, a BestFit ditch is all cut and no fill.

Slope-IQ makes the lower end of the survey the outlet: it compares the first and last points. The design falls toward the outlet the whole way; through a rise it carries on at Min Grade and you cut. (Drawn with a Depth Offset, so the design sits below the ground everywhere.) Tap Outlet: Auto only if the ditch really drains the other way; it then reads Outlet: Reversed.

The six number boxes

Under the chart sit six boxes, one per setting. On the tablet they're in one row; here they're shown in pairs so you can read them. Each has its number in the middle, with − and + buttons under it.

The six Slope-IQ number boxes, shown in pairs: DEPTH OFFSET 0.0 inches and MIN GRADE 0.05%; BOTTOM WIDTH 8 ft and SIDE SLOPE 6.0:1; MIN DEPTH 0 inches and MAX DEPTH 12 inches; each with a minus and a plus button under the number — **The number.** Tap it to type a value.
**− and +.** Small steps down and up. Each tap redraws the design.

To type a value instead of tapping − and + many times:

Tap the number in the box

For example, tap 0.0" in the DEPTH OFFSET box, the first box on the left. A small window opens with that box's name at the top, and the number keyboard opens (typing on the tablet).
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1. The number. Tap it, not the − or + under it.
Type the value

The line at the top of the window gives the allowed range, for example Enter a value (range: -360.0 to 360.0"). The box starts with the current value: press and hold the keyboard's delete key to clear it, then type the new number. A number outside the range is changed to the nearest allowed value.
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1. The value. Here, 6 inches.
Tap Set

Set is the green button at the bottom right of the small window. Tap it. The window closes and the design redraws with the new value. Cancel keeps the old one.
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1. Set. Applies the value and redraws the design.

What each box does:

Box	What it does	Default · step
DEPTH OFFSET	Lowers the whole design below the ground by this much. In BestFit the design never comes closer to the ground than the offset.	0 in · 0.5 in (±360 in)
MIN GRADE %	The flattest the design may be anywhere. Not shown in Freeform.	0.05 % · 0.01 % (0.01–5 %)
BOTTOM WIDTH	Width of the ditch bottom. Used only for Cut Vol.	Your Swath Width setting (8 ft) · 1 ft
SIDE SLOPE	Side slope as horizontal to vertical. Used only for Cut Vol.	6.0:1 · 0.5
MIN DEPTH	Draws a green dashed line this far below the ground, so you can see where the design is shallower. A guide only; it doesn't move the design.	0 in (off) · 1 in (up to 48 in)
MAX DEPTH	Draws a pink dashed Max line this far below the ground and shades any deeper cut red as Over Max. A guide only. Filled in with the first design's deepest cut, rounded up.	Deepest cut · 1 in (up to 120 in)

Design choices, like a drainage pro would make them

Minimum grade

0.05 % (0.6 in per 100 ft) is the standard floor for surface drains and what the setup suggests. A flatter floor hugs the ground and cuts less, but the water moves slower and flat stretches are what silt in and hold water. A steeper floor gives a straighter, faster ditch and more cut at the inlet end. Raise it in 0.01 % steps and watch Max Cut and Cut Vol to see what the extra fall costs.

Depth Offset for cleanouts and minimum depth

Your survey is the ground you drove. When you survey the bottom of an existing ditch to clean it out, the BestFit line sits on that bottom wherever it already drains. Add Depth Offset to take it deeper: 6 in drops the whole line 6 in, so every station is cut at least 6 in. On a new ditch across a field, the offset is how you get a ditch of some depth everywhere, not just through the rises.

Slope-IQ with Depth Offset 6.0 inches: the design sits 6 inches deeper, dark red Over Max patches where the cut goes past the 12 inch Max Depth line, Max Cut 17.6 inches, Cut Vol 995.4 cubic yards, Est. Passes 9 — **DEPTH OFFSET 6.0".** The whole design 6 in deeper.
**Over Max.** Dark red where the cut is deeper than Max Depth (here 12 in).
**Est. Passes.** Up from 6 to 9 at 2 in a pass.

Max Depth: see where you'd cut too deep

Set MAX DEPTH to the deepest cut your implement, your outlet or the field will take. The red patches show exactly where the design goes past it. Then decide: accept it, raise Min Grade or lower the offset, or draw that stretch yourself in Guided.

Min Depth: see where the ditch is too shallow

Slope-IQ with Min Depth 8 inches: a faint green dashed line drawn 8 inches below the terrain; the design line is unchanged — **Min depth line.** Faint green dashes, 8 in under the ground. Where the orange design is above it, the ditch is shallower than 8 in.
**MIN DEPTH 8".** 0 turns the line off.

Bottom width and side slope

These only change the Cut Vol estimate. Set them to the width your implement cuts and the side slope you'll leave, and the volume is a fair figure for how much dirt you're moving. Leave them alone if you don't need the number.

Set the outlet direction

Outlet: Auto compares the two ends of the survey and takes the lower one as the outlet. Flat ground or a low spot near the inlet can fool it. The button shows on BestFit and Guided; in Freeform you set the line yourself.

Tap Outlet: Auto

Outlet: Auto is the white button with an arrow at the top right of the window, left of the ✕. Tap it.
1. Outlet: Auto. Top right, left of the ✕.
Check the result

You should see the button turn orange and read Outlet: Reversed. The design now drains toward the other end. Tap it again to go back to Auto.
1. Outlet: Reversed. The water now leaves at the START end.
2. The cost. Draining against this ground means a 92 in cut and a negative Drop: your sign the direction is wrong.

Pin the outlet at a set depth

Sometimes the outlet end is fixed for you: the ditch has to come out at the depth of a culvert, a road ditch or a main drain. OUTLET DEPTH sets that depth, and BestFit works the design back upstream from it. It's on the BestFit tab only.

Tap OUTLET DEPTH: OFF

OUTLET DEPTH: OFF is the white button at the top right of the window, left of Outlet: Auto. Tap it. A window called Fixed outlet depth opens.

Top right of the Slope-IQ Design window: the OUTLET DEPTH: OFF button, left of Outlet: Auto — **OUTLET DEPTH: OFF.** Top right, left of Outlet: Auto.

Turn on Fix outlet depth

Tap the switch on the Fix outlet depth row, at the top of the window. The two boxes under it turn on.

Fixed outlet depth window with the Fix outlet depth switch off, Outlet depth 0.0 and Outlet transition 0 greyed out, a Suggest button, the note Depth limits are relaxed within this distance from the outlet. Minimum grade always applies. 0 = none. Cancel and Apply — **Fix outlet depth.** The switch is at the right end of the row.

Type the outlet depth

Tap the Outlet depth (") box. The keyboard opens (typing on the tablet). If the box already holds a number, clear it with the delete key. Type how deep the ditch must be at the outlet, in inches below the ground.

Fixed outlet depth window with the switch on, Outlet depth 18 and Outlet transition 1 — **Outlet depth (").** Here, 18 in.

Tap Suggest, or type a transition

Outlet transition (ft) is how far upstream the line may ramp from the outlet depth back to the normal design. Min and Max Depth are relaxed inside it; Min Grade never is. 0 means no ramp.

Suggest, right of the box, fills in the shortest transition, in whole feet, that keeps the rest of the run inside your depth limits. If the run already fits it says No transition needed — the run already meets the depth limits. If no distance works it says No distance in this run clears the depth limits. Change the outlet depth or the limits.

The same window: the Outlet transition box reading 1 after Suggest, and the Suggest button to its right — **Outlet transition (ft).** Type it, or let Suggest fill it in.
**Suggest.** The shortest ramp that works.

Tap Apply

Apply is the button at the bottom right of the window. Tap it. The window closes and the design redraws.

The same window, with Cancel and Apply at the bottom right — **Apply.** Bottom right.

Check the outlet end on the chart

You should see the button read the depth and transition, for example OUTLET DEPTH: 18.0" · 300 ft, in green. (In this picture a 300 ft transition was typed in, for an even ramp.) At the outlet end of the chart, the transition is shaded, with a dashed line where it starts, and the design dives to the outlet depth.

The outlet end of the Slope-IQ chart with a fixed outlet: the last 300 ft is shaded light peach with a red dashed line where it starts, and the orange design line drops down to the outlet depth at the END — **Transition.** Depth limits relaxed here; the line ramps to the outlet depth.
**Outlet.** 18 in deep, as set.

With a fixed outlet the app also tries to keep the rest of the line between Min Depth and Max Depth. Where it can't without breaking the minimum grade, it keeps the grade. In v1.5.4 a warning in this mode may borrow tile wording ("Tile shallower than minimum depth…"); read it as the ditch.

Guided: pick the points the line goes through

Tap Guided

Guided is the middle of the three tabs at the top left of the window, with a pointing-hand picture. Tap it.

You should see the design trace the ground until you tap points. The hint at the top right of the chart reads Tap terrain points to add vertices. The OUTLET DEPTH button is hidden on this tab.

Slope-IQ on the Guided tab before any taps: the design line follows the terrain exactly, hint Tap terrain points to add vertices, Undo greyed out, design strip all zero — **Guided.** The middle tab.
**Hint and Undo.** Top right of the chart.

Tap the ground at each point the ditch must pass through

Tap the dashed green ground line at each spot you want held, one tap per point. The start and end are always included. Straight lines join the points, each labelled with its grade, and never flatter than Min Grade.

Where a line bridges a hollow, the hollow shows blue as FILL.

The first part of a Guided design: white control-point circles at the start (809.4) and at about 700 ft (808.7), a straight orange line between them labelled -0.10% bridging a blue-hatched hollow, then a steeper line labelled -0.51% — **Control point.** A white circle. The design passes through it at the ground (less any offset), or lower where Min Grade needs it.
**Segment grade.** Negative means falling toward the end of the run.
**FILL.** Blue: the line bridges a low spot instead of following it.

Tap Undo if a point is wrong

Undo is at the top right of the chart. Each tap takes off the last point you added. Tapping a point again also removes it. Switching tabs clears all your points.

Guided design after one Undo: the last control point removed and the design redrawn with one segment fewer; Undo at the top right of the chart — **Undo.** One point back each tap.

Freeform: draw the line yourself

Tap Freeform

Freeform is the third tab at the top left of the window, right of Guided. Tap it.

You should see the design start as one straight line from START to END. The hint reads Tap to add/remove, drag to move. There's no MIN GRADE box, and the Outlet and OUTLET DEPTH buttons are hidden: no grade rules apply.
1. Freeform. The third tab. You set every point.
Tap the chart to add points, drag to move them

Tap the chart where you want a point. To move a point, put your finger on it and slide. Tap a point again to remove it. The start and end points can be dragged up or down but not removed. Undo, top right of the chart, steps back one change.
1 2
1. 0.34 %. A positive grade label is a stretch running back uphill toward the end. Freeform allows it; water won't follow it. Check every label before you implement.
2. A point you placed. Drag it up or down to fix the leg.

Read the design strip

The strip under the number boxes says what the design will take to build. On the tablet it's one row; here it's shown in three.

The design strip shown in three rows: DESIGN, Grade 0.173%, Max Cut 11.1 inches; Avg Cut 5.1 inches, Length 2559 ft, Drop 4.43 ft; Cut Vol 244.7 cubic yards and a green Est. Passes: 6 @ 2 inches per pass chip — **Max Cut.** The deepest cut on the run.
**Est. Passes.** How many passes, at your Max Cut Depth setting.

Item	Meaning
Grade	Overall grade from end to end.
Max Cut	The deepest cut anywhere on the run.
Avg Cut	Average cut over the stations that are cut.
Length	Length of the run.
Drop	Fall from START to END on the design. Negative when the design rises toward the END (outlet at START).
Cut Vol	Estimated cut, from Bottom Width and Side Slope.
Est. Passes: 6 @ 2"/pass	Deepest cut ÷ your Max Cut Depth setting (in Settings, under GRADING). Too many? Raise Max Cut Per Pass in the Auto-Nudge Mode window. More.

Implement the design

Tap Implement Slope

Implement Slope is the green button at the bottom right corner of the window. Tap it. A small window called Save Design opens, with the keyboard.
1. Implement Slope. Bottom right corner.
Tap Save & Implement

The name is filled in: the survey name with (Ditching) on the end. If a design from this survey was saved before, it ends in V2, V3 and so on, so earlier designs are never overwritten. Type over it if you like (press and hold the keyboard's delete key to clear it), then tap Save & Implement, the green button above the keyboard.
1. Save & Implement. Saves the design on the tablet and loads it for grading.

The Grade screen opens. Then come the Calibrate GPS? window (only when the survey came off the tablet rather than being driven just now) and the Auto-Nudge Mode window. Ditching: grade it, and Do I need a benchmark today?

Opened from Edit Design, the button reads Save Revised Design: Edit the design mid-job.

If it doesn't work

The chart says Not enough survey data: the survey has fewer than 2 points. More.
The design drains the wrong way, or Max Cut is huge: flip the outlet. More.
The design sits above the ground: a negative Depth Offset or wrong blade height. More.
The line goes past Min or Max Depth: they're guides, not limits. More.
Too many passes: More.

Did this answer your question?

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