When you’re behind the controls of a Wirtgen milling machine, precision is everything. Slope control is one of the most powerful—and misunderstood—tools in your arsenal. When used correctly, it ensures proper drainage, matches cross-slopes, and helps achieve spec with minimal rework. But knowing when and how to use it makes all the difference between a clean cut and a costly callback.
What Is Slope Control?
Slope control is a grade automation feature that adjusts one side of the milling drum relative to the other. Instead of cutting perfectly level across the width, slope control lets you tilt the drum slightly to follow an intended cross-slope—usually for water runoff or lane matching. On Wirtgen machines, this is typically adjusted via the LEVEL PRO system or 3D automation, depending on your setup.
When to Use Slope Control
Here are the most common situations where slope control is essential:
1.
Maintaining Cross-Slope for Drainage
When milling roads with built-in cross-slope (typically 2%), you’ll want to preserve or match that slope in your cut. Use slope control to follow the existing crown and prevent flat spots that collect water.
2.
Transitioning Into or Out of Superelevations
Highways and ramps often tilt (superelevate) for speed and drainage. Slope control lets you maintain that angle smoothly during milling. Without it, you’d risk creating a jagged or uneven profile.
3.
Matching a Lane or Shoulder
If you’re milling one lane next to an untouched lane or shoulder, you can use slope control to mirror the grade. This avoids harsh edges or dangerous mismatches when lanes are tied back in.
4.
Correcting a Previously Uneven Surface
Slope control can help level a wavy or improperly crowned surface by overriding inconsistent surface grade and enforcing a uniform cross-slope.
How to Set Up and Use Slope Control
Here’s a general step-by-step for Wirtgen machines, but always refer to your model’s operator manual:
1.
Start with a job walkthrough
Get with the Forman or super on the job and walk the job so you have a full understanding of what they are trying to accomplish. You may decide that slope may not be the best option.
2.
Set Your Reference Side
Pick one side to follow ground reference—usually the high side if you’re cutting a slope. Use a sonic sensor, ski, or string line to hold a consistent height.
3.
Engage Slope Control on the Opposite Side
On the other side of the drum, switch from grade control to slope mode. Set your desired cross-slope (e.g., -2.0%) and allow the system to auto-adjust during the cut.
4.
Monitor and Adjust On the Fly
Watch for signs that your slope is drifting (water pooling, uneven passes). Use manual grade adjustment sparingly if you hit unexpected surface changes like potholes, patches, or utility lids.
Pro Tips for Better Slope Control Results
- Calibrate regularly: Grade sensors can drift. Recalibrate at the start of each job. If your grade control is off your slope will be also.
- Check your sensors: Dirty or damaged sensors can cause overcorrections. Check them before each shift.
- Communicate with your crew: Let your ground man or foreman know what slope settings you’re running so they can verify with string lines or grade checks.
- Use a dual-grade setup when possible: If the entire lane needs accurate slope and elevation, reference both sides—one on grade, one on slope.
Final Thoughts
Slope control is one of the most valuable tools for producing spec-grade cuts efficiently and safely. Whether you’re milling a city street or a highway ramp, understanding when to use slope—and how to set it up—can save you hours of rework, keep your joints clean, and make your paving crew’s life a whole lot easier.