Driving downhill is one of the biggest tests when taking your CDL. Mountain passes, driving with a full and/or heavy load, and steep grades can be some of the biggest contributing factors to making driving downhill a stressful experience. Industry-wide safety is our goal and we can only get there if we share our knowledge, training, and experiences. So, here are some tips on driving downhill and how to stay safe considering those critical factors.
Mountain Passes
Mountain passes often have a lot of hard corners and drivers who are going too fast will lose control. Add rain/ice/snow into that equation and it’s even more treacherous. Many drivers can make the mistake of thinking that once they are near the bottom of the hill they are in the clear, and so they pick up speed. This can often be a mistake as their can be a patch of ice on the road or an unexpected curve.
Another great tip for navigating down hills in mountain passes is to not follow in the tracks of the vehicle ahead of you. It’s safer to make your own set of tracks by pulling a little bit to the right, run one set of your drives on the should of the road in the hopes of getting the traction benefit of the gravel from the road shoulder. Only do this if you feel confident.
Thirdly, don’t give the truck too much fuel – if you do you will cause the wheels to spin. Gradually give the truck power to ensure you stay in control.
And most importantly, have your chains ready to go – watch for signs advising you of chain up areas.
Full Loads
Drivers must consider whether their trailers are full or empty, as this will drastically affect their navigation on hills. As a rule, if you hare carrying less than 25,000lbs, you can travel at the posted truck speed (or 10-15mph below the regular posted speed limit). If you are carrying more than 25,000lbs, you will probably want to reduce your speed to 10mph below the posted truck sed if there is one (or 35mph if there isn’t one). this general rule is when the road is dry, and conditions are favorable. When faced with wet or slick roads, you will need to make a judgement call on how much more to reduce your speed depending on if you are loaded or empty.
Steep Grades
Typically, you will be aware when a steep grade is coming up – there will be signs to tell you what speed is best for trucks, and there might be a brake check at the top of the hill.
To handle steep grades, the key is to shift the transmission to a low gear before starting down the grade. Don’t try to downshift after you are progressing down the hill and your speed has increased – if you do this, you may not be able to get back into any gear, will probably damage your transmission, and all engine braking effect will be lost. Going into a lower gear helps control your speed and you won’t have to brake as sharply.
Some use this rule for older trucks: use the same gear going down a hill that you would need to climb the hill. Newer trucks have streamlined designs, more powerful engines and can navigate downhill will less friction and air drag. So, newer trucks must use lower gears to go down hills than they do to go up. Taking this into account, along with getting to know your vehicle will let you know what’s appropriate.
What to Do if you Find Yourself in an Unsafe Situation
If you find yourself in the situation where you are out of control and heading down a hill, find the escape/runaway ramp. If there is one, there’ll be signs. Many escape ramps use soft gravel that resists the motion of the vehicle and brings it to a stop. As best you can, keep calm in these situations and be able to make your corrective move as soon as you realize you’re in trouble. The longer you wait, the more your truck faster the vehicle will go, and the harder it will be to stop.
