Being a good driver means being able to adjust your driving according to your surroundings. Anyone with a driver’s license can drive in a flat, smooth area. However, it takes some skills and knowledge to drive in mountainous areas with drastic changes in road grade. It’ll put you and your vehicle’s abilities to the test!
Today, we’re talking about road grade and what it means exactly. We’ll also provide several things to watch for when driving on grades. Applying these tips will help you be a better driver. Let’s dive in!
What Is Road Grade and Why Is It Important?
When you hear the term “road grade,” you might have flashbacks to the report cards or tests you received as a kid. However, the term has less to do with the road’s quality and more with its slope. Road grade refers to the amount of a road’s rise or drop in a given distance.
In a real-life scenario, a 5% grade means the road will rise or fall 5 feet for 100 linear feet. This means if you see a sign that warns of a 5% grade for the next 4 miles, you’re going up or down 1,056 feet in the next four miles of driving.
This is important information for drivers, especially those towing heavier loads. Drivers want to avoid using their brakes for extended amounts of time as it can cause them to heat up, increasing the wear and tear on them. In extreme situations, this can result in total brake failure and leave the driver unable to stop the vehicle.
What Is the Maximum Grade for a Road?
Increased road grades can be very dangerous and challenging for drivers. As a result, the maximum grade for a federally funded road in the United States is 6%. However, this increases to 7% in mountainous areas as long as the road’s speed limit is below 60 miles per hour.
One of the most popular graded roads is I-70, which runs from Cove Fort, Utah, to Baltimore, MD. The most challenging section of the road cuts through the heart of the Rocky Mountains. Drivers descend from 11,158 feet at Eisenhower Tunnel to 5,279 feet in the city of Denver. Much of the road is the maximum 7% grade the entire way.
When you get off the interstate, however, road grades do not have limits. While most public roads remain under 10%, we have seen road signs up to 25% in our travels.
Pro Tip: These Scariest Roads in America have dangerous driving conditions, like increased road grades.
What Is the Steepest Road in the USA?
Waipio Valley Road in Hawaii takes the cake as the steepest road in the USA. This road maxes out at a 45% gradient. While only four-wheel drive vehicles are permitted on Waipio Valley Road, you can also make the 1.4-mile trek on foot.
7 Things to Watch for When Driving on Grades
No matter how long you’ve been driving, there are several things you should always watch for when driving on grades. Let’s look at what you should keep your eyes peeled for on graded roads.
Road Grade Signs
Warning signs are the yellow and black-lettered signs you see on the sides of the road. Most of these signs are diamond-shaped and depict a truck going down a hill. These alert you to expect a drastic change in the road grade.
These signs will often include the road grade percentage below the image. If you see one of these signs, you should start preparing yourself and your vehicle for the changing conditions. This may mean turning on your vehicle’s exhaust brakes or other capabilities to navigate the road.
Speed Limits
You may be on an interstate, but the speed limits can drop considerably on graded roads. The faster your vehicle moves, the harder it will be to stop. Gravity will also cause a vehicle to gain momentum as it travels down a graded highway. You must obey the speed limits when driving on a graded road.
Speed is a leading factor in many accidents, especially on graded roads. Your speed can quickly get out of control in these areas. The super-slow speed limits keep you and other drivers safe on the road. Slow down and enjoy the views.
Curve Speed Signs
Many graded roads have not only declines and inclines but also curves. You should look for signs indicating curves are ahead to adjust your speed. These signs will indicate the recommended speed for safely navigating them.
This isn’t the time to show off your vehicle’s performance or ability to handle curves. Failing to navigate one of these curves correctly can be dangerous and even deadly. Watch out for the curve speed signs and adjust your speed accordingly.
Heavy Vehicles Going Slow
It doesn’t matter whether you’re going up or down. Heavy vehicles are going to be going slow. Navigating intense road grades can be very taxing for these vehicles. They reduce their speeds to help avoid any issues with their brakes or transmissions. Laws typically require these vehicles to use the right lanes and stay out of the left lanes. However, slower traffic can be in any lane, and you’ll want to watch for them.
Smaller Vehicles Going Fast
On the opposite side of the spectrum, smaller vehicles are lighter and typically have an easier time navigating graded roads. Drivers of smaller vehicles can overestimate their ability to slow down or may change lanes quickly to avoid slower traffic. Keep an eye out for these drivers, especially in crowded situations. They can quickly cause a dangerous problem as they recklessly maneuver the highway.
Overheated Vehicles on the Side of the Road
Conquering a mountain pass or other steep grade is very taxing on a vehicle, especially towing vehicles. It’s not uncommon to see vehicles overheating on the side of the road or taking a break. Give them and their owners plenty of space as you pass by to avoid any potential accidents.
Runaway Ramps
A runaway ramp can be a lifesaver if you’re experiencing a brake failure. While many think these are only available for semi trucks, that’s not true. Runaway ramps are safety features on highways in mountainous regions that drivers of any vehicle can use. However, if you need to use a runaway ramp, don’t expect your stop to feel like you’re landing on a cloud.
Runaway ramp lanes increase in depth the further you travel into them. They’re filled with sand or gravel, and the vehicle’s axles sink into them to stop the vehicle’s forward momentum. Stopping can be rather abrupt and violent, but they get the job done.
There are typically signs indicating you’re approaching a runaway ramp. As you watch the traffic around you, be mindful of vehicles trying to position themselves to utilize an upcoming runaway ramp. If you want to avoid being in an accident, move out of their way and let them pass on your right.
Tips for Driving on Roads with Grades
If you have an upcoming road trip that will have you traveling on roads with grades, we have a few tips for you. Following these tips will help ensure you and your vehicle are ready on steep roads.
Stay Within Towing Capacities
Manufacturers set towing capacities for a reason, primarily safety. Your vehicle may be tough or strong enough to pull more weight than its rating implies. However, stopping is also important. Road grades can push your vehicle and its components to their limits. Exceeding the towing capacities of your vehicle is never a good idea.
It’s important that you know your vehicle’s towing capacities and that you weigh any loads you are towing. Not following them can put you and others on the road in a dangerous and deadly situation. We’ve seen far too many less-than-capable vehicles towing large amounts of weight during our travels.
Inspect Your Brakes
Before heading off on an adventure that will take you over graded roads, you should inspect your brakes. You don’t want to discover that you need to replace your brakes as you’re barreling down a steep grade. You can do thousands of dollars of damage and be stuck with a costly recovery bill if you have to use a runaway ramp.
If you’re not knowledgeable about vehicles, have a trusted mechanic look over your brakes and other essential components. You want to ensure you and your vehicle can safely navigate road grades during your adventures.
Pro Tip: Curious how air brakes work? Find out how this 150 Year Old Technology Still Stops Big Vehicles.
Monitor Your Engine and Transmission Temperatures
As we’ve said repeatedly, road grades can cause your vehicle to work harder than normal. This typically results in the temperatures of your engine and transmission increasing. If you’re not careful, you may cause your engine to overheat. You’ll want to keep your engine between 195 and 220 degrees and your transmission within 175 to 220 degrees.
There will likely be gauges on your dashboard that indicate the engine and transmission temperatures. Find a safe place with plenty of space to pull off the road and let your vehicle cool down. Keep your engine running so that it allows the engine fan to cool it down while you’re parked.
Some roads with intense grades will have designated spots for vehicles to park while they cool down. Don’t push the limits of your vehicle too much, or you’ll do a tremendous amount of damage and end up with an expensive repair bill.
Use Your Engine Brake on Roads With Grades
Some vehicles include engine brakes to take some of the load off a vehicle’s brakes. If yours has one, it’s a good idea to use it. This can help you control your speed without having to use your brakes. When facing an extended downward grade, these can save your brakes and prevent a dangerous situation. If you have it, use it!
Listen to Your Vehicle
The best drivers use almost all of their senses when navigating road grades, especially their sense of hearing. Turn off the music and limit conversations around you so you can listen to your vehicle. If it sounds like it’s struggling or the engine is changing tones, you might need to adjust your driving.
Being alert to how your vehicle is performing can help you avoid causing damage to it. If your vehicle is struggling, pull over to the side of the road and inspect it. Look for any abnormal wear and tear that might be causing the noise.
Pro Tip: Long driving days can make it hard to stay alert while on the road. Use these 10 Simple Ways to Make RV Driving Days Not Suck.
Stay Alert and Safe While Driving on Roads With Grades
If you follow our tips and ensure a capable vehicle, road grades don’t have to be scary. However, extreme road grades demand respect, and you should always approach them cautiously. This helps ensure you and other drivers are as safe as possible and that everyone arrives at their destination safely.
Road grades are just one of the many hazards that can cause accidents. Learn the 5 Most Common Causes of RV Accidents (and How to Avoid Them).
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Frank Rushing
Friday 1st of September 2023
Good information. I've had to learn much of this by OJT, trial and error methods. Living in a rural Ozark community I grew up pulling trailers, stock trailers, equipment and now a travel trailer. While our region is not known for high peaks, we do have some of the steepest grades, 9 to 11% on state highways are not uncommon, generally only a couple miles in length but a couple miles at 11% is quite a strain. My truck has transmission temperature Guage which I keep a close eye on. I also downshift manually on grades. Use the "tow mode" when trailering, I have been told by mechanics that this provides a cooling boost for the transmission, but on steep grades switching from tow mode to manual shift is my personal preference. As long as the transmission temperature is in the desirable range all is good.
MOTM Editor
Monday 25th of September 2023
Hey Frank! Thank you for sharing your experience. It's always valuable to hear from someone with hands-on knowledge.
Joe the Computerguy
Thursday 4th of August 2022
No joke about grades. I came over Monarch Pass with my class A motorhome in May. The next day my engine self destructed. Some evidence points to the length of the grade and engine RPMs. $17,000 to fix plus now going on over $5k in hotels and eating out waiting for it to be repaired.
Jerry
Friday 1st of September 2023
@Joe the Computerguy, . Joe, what engine/drivetrain did you have, how old is your rig, and what type of failure did it experience? What was the diagnosed cause of the failure?