Similar to the passing basics advised for you in the Passing Me chapter, I work to allow adequate distance behind you while following you. A general guideline for truck drivers’ following distance behind traffic in good weather and road conditions is one second of travel for every 10 miles per hour of speed. At 60 miles per hour this distance is 528 feet or one tenth of a mile.
While I prefer this following distance, it is hard to maintain in traffic—even if I hang back, drivers fill in the space in front of me. At a practical minimum I stay out of the “Close and Directly in Front of My Truck” risk zone. When you have passed my truck or are in front of it and travelling as fast as or faster than it, you can help by not allowing your vehicle to get too close, per the following excerpts from the Risk Zone: Close and Directly in Front of My Truck tip.
Definitions of “Close” and “Lead Threshold”
By “close” in front of my truck I mean any distance less than the distance my truck is traveling in 2 seconds. For example if my truck and your vehicle were traveling at 60 mph (miles per hour) the “close” distance (risk zone) in front of my truck would be anything less than 180 feet (rounded up) or approximately 12 compact-size 14 1/2-foot car lengths or approximately 2 1/2 big rig truck lengths. This lead threshold is arbitrary, not government-mandated. It is my way of estimating a minimal time window for me to recognize and respond to any sudden action you take.
In any situations in which you brake hard or even moderately within this risk zone, there is a possibility of a rear end collision with you. To avoid a collision, first I have to notice your braking, and your brake lights don’t tell me the rate at which you’re slowing or stopping. Once I’ve seen your brake lights (or noticed your slowing if your lights don’t work), I will immediately brake moderately and then hard if I see I am closing on you. If I see you slowing drastically I will look for an “out,” a maneuver to avoid colliding with your vehicle. That generally means a lane change or steering onto a highway shoulder.
Now imagine this process happening at 60 mph within 2 to 4 seconds (I have somewhat longer than the 2 second lead threshold assuming you don’t stop instantly). This is not enough time for me to do a lot, considering it takes about 1/10 of a mile (500 feet) to stop my fully loaded truck from 60 mph in good road and weather conditions and much less distance to stop your personal vehicle. So I think we should treat this 2 second lead threshold as our practical basic minimum on the open road at highway speeds. Anything less definitely increases your risk. Ideally you should stay well outside the lead threshold to minimize your risk.
Once you’ve passed my truck, please, please do not slow down and settle in this zone! Depending on other traffic around us I will wait momentarily for you to pull away and if you don’t, I will slow down to let you get farther ahead and then resume my cruising speed (this burns extra fuel) or I will prepare to pass you. Preferably you will pull much farther away from my truck as soon as it’s safe and lawful to do so. This is a very important component of defensive driving: It will make both of us safer. You will have to pay less attention to my truck behind you and I will be able to pay less attention to your vehicle and more attention to other factors around my truck.
The lead threshold and collision avoidance maneuvering described above provide minimal protection from some action taken by you alone, such as slowing/stopping for a flat or blown tire, a small animal, road debris or other surface problem, or some disturbance inside your vehicle. In a more obvious emergency happening in front of you, there is a good possibility that I will have seen it (from my higher vantage point) and will have begun braking hard and preparing for evasive action simultaneously with you or perhaps earlier than you.
The lead threshold is not always practical in light of current automobile performance and driver behavior in good weather and road conditions. For example the threshold is not easy to maintain in heavier traffic such as on multiple-lane city freeways. In those situations it is generally safer for me and other truck drivers to “go with the flow” at or close to traffic speed than to slow down significantly. Whether I’m in the right lane or in one of the lanes to the left, some drivers in passenger vehicles will still pass me on the left or right and then fill the space on my left, right or directly in front. In such conditions I am doing well if I can maintain a truck length (approximately 5 compact-size car lengths) of space in front of me across the 3 lanes, though I will constantly try to extend it.
Changing Lanes Behind You
With your vehicle at least a lead threshold ahead of me, I should be able to make routine lane changes to the left to bypass situations such as emergency vehicles or highway maintenance equipment and personnel or other vehicles and people on the right shoulder, and also any lane changes from left to right. (Of course this assumes no drivers are alongside me.)
In emergencies requiring lane changes from both of us, I prefer to stay behind you. I will brake hard and possibly swerve onto the right shoulder or the narrow left shoulder or even into the median to try to avoid rear ending you. Obviously the greater your lead above our threshold, the easier and safer this will be.
You are in a risk zone when a truck follows you at less than the distance your vehicle travels in one second.
It is safer to stay two seconds of travel or more ahead of a truck.
Allow a safe lead distance before returning to the lane of a truck or any other vehicle you have passed.
Increase your following distance in bad weather and/or bad road conditions or if you see snow or ice on top of the trailer in front of you.
As a general rule, move out of all risk zones around a truck as soon as it is practical, safe and lawful to do so.