This story stems from a horrific truck crash that occurred on Interstate 70 near Denver, Colo. in late April 2019. An apparently out-of-control truck careened down an 8-km stretch of steep highway at 135 km/h before slamming into a line of stopped traffic.
Four people died in the ensuing inferno. A dozen others were seriously injured. The speed limit for trucks on that hill is posted at 70 km/h, yet witnesses have video showing the truck scorching past a runaway-truck ramp at well over 100 km/h.
Published reports indicate the driver, 23-year-old Rogel Lazaro Aguilera-Mederos of Texas, had his commercial driver’s licence (CDL) for less than three years and had only recently operated outside his home state.
There’s no indication of how much mountain driving experience he had, but it’s safe to say he didn’t get any mountain-related experience when took his CDL course in Houston. If anything, he may have read the 1.5 pages on the subject in the Texas CDL training manual.
Which isn’t much different from what many Canadian CDL trainees get.
“Far too many commercial drivers today bet the house while descending steep grades.”– Larry Hall, owner-operator
There are few areas in this country that have hills, never mind mountains, big enough for related training. That said, many newly minted Class A and Class 1 drivers eventually find themselves in places like B.C. and Colorado and Western Pennsylvania and West Virginia without the benefit of a thorough understanding of how to manage long downhill grades in heavy trucks.
“Far too many commercial drivers today bet the house while descending steep grades,” says Larry Hall, a veteran B.C.-based owner-operator and organizer of a group calling itself ADEPT (Assembly of Drivers, Educators and Professional Truckers).
“Equipment today provides a false sense of security. With upwards of 600 horsepower of engine-braking ability, there seems to be little or no concern for the ‘what if’ scenario. What if the engine brake fails? What if you come around a corner and traffic is stopped, or there is an animal standing in the lane? Those drivers have no Plan B.”
Limits of entry-level training
Entry-level driver training is a hot topic today in Canada. While most agree that it’s a step in the right direction, entry-level training is just that. Mountain driving, like winter driving, is an advanced driving skill.
“Mountain driving requires a level of skill higher than most entry-level drivers can safely manage,” says Ed Popkie, president of the 5th Wheel Training Institute in New Liskeard, Ont.
“Our students graduate with the skills they need to safely handle city, highway and regional work. Asking them to cope with mountains at that early stage of their learning curve would probably be too much for most entry-level drivers.”
Popkie says there have been a greater number of truck crashes on Ontario’s Hwy. 11 between Martin River and Hearst in recent winters, many of which he attributes to inexperience.
“Drivers are crossing over the centerlines in long curves, and they are trying to pass in [the] limited number of passing lanes we have here,” he says. “Those moves suggest to me the drivers aren’t familiar with the risks of driving on two-lane roads. There’s very little room for error around here – and in the mountains.
“I’d like to believe that carriers would pair new drivers with experienced drivers to ease them into these advanced driving situations,” he adds. “But every winter we see plenty of evidence that suggests otherwise.”
How do flat-landers teach mountain driving?
Aside from the question of whether or not advanced driving skills can or should be taught in an entry-level program, there’s the problem of geography. You can’t do much more than lecture trainees about mountain driving in much of Canada. The requisite terrain simply doesn’t exist.
Andy Roberts owns and operates a driving school called Mountain Transport Institute in Castlegar, B.C., which is located in the Kootenays in the southeastern part of the province.
It’s quite literally surrounded by mountains. MTI offers tractor-trailer driving instruction on several levels from a four-week entry-level course to an eight-week advanced course. It also offers a week-long mountain driving program that includes four hours of classroom instruction, two hours of shifting in a simulator, and 24 hours of in-truck instruction on any of the four mountain passes located near the school.
Perhaps surprisingly, even B.C. does not include any formal mountain driving training in its existing CDL training or testing.
Roberts says the B.C. driver’s handbook contains a couple of pages of decent information on the topic, but drivers are not necessarily tested on the material, and there’s no mountain component to the driving test in a province with more mountains than anywhere else in Canada.
“My entry-level program includes at least one trip down a mountain grade, and my advanced students get two days out there,” Roberts says. “It’s not ideal, but at least the entry-level driver gets some exposure to the driving techniques required to drive safely in the mountains.”
Facing mountains the first time
Drivers exposed to mountains for the first time face a dilemma. They often don’t know what lays ahead, and therefore won’t be aware of what speed they should be traveling.
Some grades have signs that display a profile of the hill; some signage offers ambiguous warnings like, “Use Lower Gear” or “Slow Down”. But lower than what, or how slow?
An Arizona company completed a six-month trial of a technology designed to provide drivers guidance and warnings about the proper speeds to use on slopes and curves. Research indicated drivers were operating perilously close to the rollover thresholds of their trucks, and operating much faster on hills than proper mountain driving techniques would suggest.
“All drivers were running very close to the tip-over threshold on the curves.”– Garth Lawrence, Road-Aware Safety Systems
Road-Aware Safety Systems combines detailed GPS maps and accurate three-dimensional road geometry with known values on vehicle dynamics (truck configuration and load center of gravity, etc.) to determine safe travel speeds.
“Our data showed all drivers were running very close to the tip-over threshold on the curves, and well above ‘engine brake-only’ speeds on the slopes,” says Garth Lawrence, the company’s managing director. “After we briefed the drivers on the risks of excessive speed they did slow down in the curves, but they continued to drive faster than the recommended speed on the hills.”
Recommended speed in this case was calculated by the Road-Aware application, and was based on the weight of the load, the steepness of the slope, and the engine’s retarding power. Drivers were urged to descend the grades using engine braking only, saving the service brakes for possible emergency stops.
“In about half of the slope runs, drivers reduced their speed by using brake snubbing to slow the truck, but did not get down to the recommended safe descent speed,” says Lawrence.
“Many times, we saw drivers running 20 mph or more over the recommended safe descent speed, driving right past a runaway truck ramp that the Arizona DOT says is used about twice a week by runaway trucks. For some reason, drivers seem more willing to accept ‘advice’ regarding speed in curves, but they are much more cavalier about slopes.”
The problem, Lawrence says, is that drivers are not provided an accurate recommended safe speed based on location, road geometry and vehicle dynamics.
“The signs say, ‘slow down’, but not to what speed.”
Safe mountain descents
According to Roberts, drivers should come down a grade using only the engine brake to maintain the descent speed. He says drivers should not need to use the service brakes to slow the truck if they are driving at the appropriate speed.
The engine brake provides the most retarding power at a higher rpm, so keep the engine speed in the 1,800- to 2,000-rpm range. If this slows the truck too much, use Position 1 or 2 on the engine brake rather than upshifting to a higher gear.
“If you need a service brake application to check the speed, you’re in too high a gear,” he says. “Conversely, if you are running the engine brake at 1,500 to 1,600 rpm on Position 3, you’re in too low a gear.
“The steepness of the grade will vary, so toggle the engine brake between the three positions to maintain a safe, steady speed,” says Roberts. “Use Position 3 on the steeper portions, and toggle back to Position 2 or 1 on the less-steep portions of the hill. If you’re in the right gear you should not need to apply the service brakes to slow the truck.”
About engine speeds
In recent years, much emphasis has been placed on keeping engine speeds as low as possible to conserve fuel, so 1,800-2,000 rpm may be forbidden territory for some drivers. You are not using any fuel when using the engine brake (no more than you would at idle).
With the engine brake on, the engine is acting like a big air compressor that’s driven by the momentum of the truck via the drive wheels. Keep the engine speed high, and don’t worry about fuel economy.
Some automated transmissions are programmed to upshift automatically when engine speed reaches a certain point. While running the engine at 1,800-2,000 rpm, you may need to place the transmission in “manual” or “hold” mode to prevent an upshift. If you are going too fast to begin with, even at high rpm, the weight and speed of the truck – coupled with the steepness of the grade – may eventually cause the transmission to upshift to protect the engine from overspeeding.
Obviously, the problem there is not an inadequate engine brake. It’s that the truck is going too fast for the engine brake to maintain a safe speed.
“If you get into the wrong gear, the time to fix that is at the top of the hill before the brakes get too hot,” adds Roberts.
Drivers were once told to “use the same gear to come down the hill that you used when climbing the hill”. But that doesn’t always apply today.
“Engines are more powerful than they once were and may be capable of climbing faster than they can safely be driven down the hill,” Roberts says. “Besides, you may have a different load on coming down than when you went up the hill, or you may have never been on that hill before.”
The best course of action is still to choose a gear that will allow the truck to maintain a speed where the engine rpm is in the 1,800- to 2,000-rpm range in any of the three engine brake positions, depending on the steepness of the grade.
What about disc brakes?
All the technical detail we have discussed here, so far, relates to drum brakes.
Drum brakes are subject to brake fade because excessive heat can change the lining’s friction properties, and the drum expands as it gets hotter. Disc brakes are fundamentally different in that the rotor, which rotates between two brake pads, expands toward the friction material as
it gets hotter, shortening the application stroke and actually improving brake performance.
If the tractor has discs and the trailer has drums, or vice versa, an imbalance situation could result where the disc-equipped vehicle is doing more of the work, causing the brakes to wear faster.
However, even with disc brakes, the weight and speed considerations still apply. A loaded truck barreling down a hill will need a longer distance to stop than when it’s operating on level ground.
If you stick with Roberts’ advice on how to descend a mount grade, it won’t matter if you have discs or drums because you won’t be using any brake on the hill anyway, right?
5 tips to descending a mountain grade
- Make sure your brakes are properly adjusted and in good working order before venturing into mountainous terrain.
- Slow way down or stop in a brake check area at the top of the hill while the brakes are still cool.
- Proceed down the hill in a gear that allows the truck to maintain a speed where the engine rpm is in the 1,800- to 2,000-rpm range in any of the three engine brake positions, depending on the steepness of the grade – and without making a service-brake application.
- Avoid the temptation to upshift if you are seemingly going too slow. Use the engine brake to control vehicle speed. The grade might get steeper around the next curve.
- Ignore the speed other drivers are doing. They may be lightly loaded, inexperienced, or driving dangerously fast for conditions.
This article originally appeared in the July 2019 edition of Today’s Trucking.
Have your say
This is a moderated forum. Comments will no longer be published unless they are accompanied by a first and last name and a verifiable email address. (Today's Trucking will not publish or share the email address.) Profane language and content deemed to be libelous, racist, or threatening in nature will not be published under any circumstances.