Long mountain grades — Wolf Creek Pass (CO), Cabbage Pass (OR), Donner Pass (CA), Snoqualmie (WA), Vail Pass (CO), Eisenhower Tunnel approach (CO), Loveland Pass — challenge truck drivers more than any other terrain. Mountain driving errors cause some of the most catastrophic CMV accidents because the consequences scale with grade and speed.
Pre-grade preparation
Stop at the top of the grade. Walk around the truck. Verify air pressure is at full system pressure (typically 120 to 140 psi). Tap the brakes gently to listen for unusual sounds. Check that the engine is at normal operating temperature (cold engines can stall on long descents). Verify your trip-planning notes and any local advisories.
Gear selection — descend in the gear you would climb in
The single most important rule of mountain descent: select the same gear (or one lower) you would use to climb the same grade. A typical 6%, 5-mile downgrade descended in a too-high gear gives you no engine compression to slow the load — you'll be on the brakes the whole way down, and brakes overheat catastrophically.
Engine brakes and Jake brakes
Most modern Class 8 trucks have engine compression brakes ("Jake brakes" / "Jacobs brakes" in commercial parlance) that use the engine's compression cycle to slow the vehicle. Engine brakes do not consume fuel and do not heat the service brakes. Activate engine brakes for any descent over 3% grade or more than 1 mile in length. Some local jurisdictions prohibit engine brakes due to noise — watch for "no engine brake" signs.
Service brake snub-and-release
If engine braking alone isn't enough to maintain safe speed, use the service brakes in firm "snubs" — apply firmly enough to drop 5 mph below your target speed, release, allow the truck to accelerate back to target speed, then snub again. Do not "ride" the brakes — continuous brake application overheats the linings and causes brake fade or fire.
Recognizing brake fade
If the brake pedal feels softer or the truck doesn't slow as expected when applied, you're experiencing brake fade. Immediately downshift to the lowest available gear to maximize engine braking, watch for a runaway-truck ramp (mandatory if available), and if you can't maintain control, take the ramp regardless of cosmetic damage to the truck.
Runaway-truck ramps
These are bedded ramps designed to bring a runaway truck to a controlled stop — typically arrestor beds of loose gravel, sand, or aggregate. Use them. They will damage the truck's tires and undercarriage but they will save your life and the lives of other motorists below you. Tow recovery from a runaway ramp typically costs $5,000 to $15,000 — a fraction of the cost of a runaway crash.
Local route knowledge
Most major mountain corridors have specific reputation for problem grades. Talk to drivers who run the route regularly, watch route-specific YouTube videos before your first attempt, and don't be the new driver who ignores warnings. The "Eisenhower descent" on I-70 west of Denver claims experienced drivers every year.