Passing Me on Grades

Last Edited: July 19, 2019 // by TruckerScape, Inc.

Passing Me Going Uphill

When you’ve passed my truck and returned to the right lane in front of it as we’re going uphill, your lead threshold (minimum lead distance) decreases as my truck’s speed and stopping distance decrease.  In most cases you should be able to pull well ahead of my truck and beyond your lead threshold (see the Passing Me Basics tip).

Frequently on extended grades, an interstate or highway with two lanes in both directions is expanded to three or more uphill lanes.  This is where drivers in faster personal vehicles can help trucks by staying left in the passing lane(s) as much as possible.  This allows truck drivers going uphill to use a middle lane and the right lane so faster trucks can pass slower trucks and the occasional slower personal vehicle on the left.

Unfortunately many personal vehicle drivers in a hurry use the middle lane(s) when they could safely use the left lane(s).  This traps faster truck drivers behind slower vehicles and forces them to bunch up in the right lane.  When I have to slow down, downshift and lose momentum behind another truck or slow personal vehicle in the right lane, my truck burns more fuel.  On some mountain climbs my truck may burn as much as an extra gallon.  This adds up to a lot of extra fuel consumed annually by my truck and other trucks in the same situation.

Passing Me Going Downhill

On steep downhill grades such as mountain pass descents, signs restrict truck drivers to the right lane(s) and require them to control their speeds by downshifting and using engine brakes and/or service brakes.  Personal vehicle drivers can help trucks on highways with three or more descent lanes where trucks are permitted to use the right two lanes.  Drivers in heavier trucks gear down more than those with lighter loads.  Leaving the right two lanes free whenever possible allows drivers with lighter loads to pass the slower trucks and still descend safely and lawfully with less fuel burned.  Though all drivers are in lower gears and using engine brakes and/or service brakes, you should still stay well beyond the lead thresholds.

On less steep downhill grades, trucks may be permitted to travel at highway speeds.  Descending these however, is very risky if you pass me and then settle close in front of my truck (see the Risk Zone:  Close and Directly in Front of My Truck and the Risk Zone:  Close in Front of My Truck and in the Left Lane Next to Mine tips).  Some drivers seem to forget how much more difficult it is to control and slow/stop a truck suddenly from highway speed downhill.  You should extend your lead significantly, preferably to 1/10 of a mile (500 feet) or more if possible.

Passing You Going uphill

On extended grades I do not pass many vehicles.  My truck slows down going uphill, and often I have to control my truck’s speed going downhill by downshifting and using engine brakes and service brakes.

Going uphill, I may have to pass a personal vehicle or a truck towing a heavily loaded trailer that is laboring even harder than my truck.  Another example is when the engine of a vehicle, usually from some low altitude location, is set to burn too rich (burn too much fuel for the available oxygen) on a high altitude mountain pass.  In that case the driver may have to creep uphill in the right lane, hoping to get over the summit and down off the pass where the engine will regain power and speed.  In bad weather and/or road conditions a personal vehicle driver may be so uncomfortable travelling at the traffic flow speed that I have to pass.

In almost every case I will pass on the driver’s left.  On an interstate or highway with two lanes in both directions, I may have to slow down behind the other vehicle in the right lane until there is a break in traffic in the left lane.  Then I have to judge whether or not I can accelerate around the vehicle.  Sometimes as I get alongside it in the left lane, it picks up speed.  Then I have to decide whether to persist and complete the pass or cancel it, slow down and return to the right lane behind the other vehicle.  On highways with three or more uphill lanes, I still have to pick my spots in a middle lane to pass slower vehicles in the right lane.

Passing is usually a slow process and I have to impose on the patience of the drivers behind me.  If I am passing you going uphill, please let me by.   Then if you pick up more speed, you can pass me back.  That reduces the inconvenience to other drivers behind us who are waiting to pass.

Passing You Going Downhill

On steep descents a vehicle such as a heavily loaded truck, a personal vehicle towing a heavily loaded trailer or a vehicle whose driver is overly cautious in bad weather and/or bad road conditions may travel so slowly that I have to pass.  While I’m passing you, please don’t speed up—trapping me alongside you on a steep descent puts me and you in danger (see the tips on risk zones alongside my truck).  If you want to pick up speed, you can always let me by and then pass me back.

If you do pass me back and/or you’re descending in front of me, you should pull well ahead of my truck, beyond your lead threshold when it’s safe and lawful to do so (see the Risk Zone:  Close and Directly in Front of My Truck and the Risk Zone:  Close in Front of My Truck and in the Left Lane Next to Mine tips).  Even though I have geared down and am using engine brakes and/or service brakes, give yourself the safety and peace of mind that the extra space provides.


On extended uphill and downhill grades where highways have been expanded to three or more lanes, stay left in the passing lane(s) as much as possible to give faster trucks an extra right lane to pass slower ones and conserve fuel.

Once you’ve passed a truck, maintain a safe lead and extend your lead significantly on downhill grades.

If a truck is passing you on your left on an uphill or downhill grade, let it by and then pass it back if you pick up speed.

TruckerScape, Inc. is not responsible for any damages or losses incurred by you in using this website.

© 2013-2022 TruckerScape, Inc.
Any copying or other reproduction or distribution of this material is expressly prohibited without written permission from TruckerScape, Inc. See our Terms of Use & Privacy Policy for more information.