Hill / Steep Grade Sign
The hill sign, also called the steep grade sign, is a diamond-shaped yellow warning sign with a black symbol showing a truck on an incline, often accompanied by a percentage indicating the grade (such as "8% GRADE"). This sign warns that a steep hill — either uphill or downhill — is ahead. The percentage tells you how much the road rises or falls per hundred feet of horizontal distance. For example, a 6% grade means the road drops 6 feet for every 100 feet of forward travel. Steep downgrades are especially dangerous because your vehicle gains speed from gravity, putting extra demand on your brakes. On long, steep hills, riding your brakes can cause brake fade — where the brakes overheat and lose effectiveness. Instead, use a lower gear to let engine compression help control your speed, and apply brakes intermittently in a technique called "snub braking." On steep uphills, your vehicle may lose power and slow significantly. Use a lower gear to maintain momentum and watch your engine temperature. Some steep hills have runaway truck ramps — gravel or sand escape ramps on the downgrade side that can stop a vehicle that has lost its brakes.
Rules & What to Do
On downgrades, shift to a lower gear before the hill begins. Use engine braking to control speed. Apply brakes firmly for short periods rather than riding them continuously. On upgrades, use a lower gear and monitor engine temperature. Watch for slow-moving vehicles.
Penalties
No direct penalty for the warning sign. However, losing control on a steep grade due to brake failure or excessive speed can result in reckless driving charges with fines of $200-$500+ and potentially criminal charges if others are injured.
For Commercial Drivers
Hills and steep grades are one of the greatest hazards for CDL drivers. Loaded trucks can quickly reach dangerous speeds on downgrades. Use the proper braking technique: establish a safe speed, then use the snub braking method — apply brakes firmly to reduce speed by 5 mph below your target, release, and repeat. Start in a gear low enough to maintain control without over-relying on brakes. If brakes fail, use the runaway truck ramp. Downgrade accidents involving commercial vehicles are often fatal — this is one area where there is zero margin for error.
Frequently Asked Questions
What does the hill sign mean?
The hill sign warns of a steep grade ahead — either an uphill or downhill slope. The percentage number on the sign tells you how steep the grade is. Shift to a lower gear and prepare for the change in grade.
What does a 6% grade mean?
A 6% grade means the road drops (or rises) 6 feet for every 100 feet of horizontal distance. That's a significant slope that requires gear reduction and careful speed management, especially for heavy vehicles.
What are runaway truck ramps?
Runaway truck ramps are escape ramps filled with gravel, sand, or arresting beds built alongside steep downgrades. If a truck's brakes fail, the driver can steer into the ramp, which slows and stops the vehicle safely.