Being constantly aware of your rearward Tractor Trajectory is very important.

Often, I find that new drivers don’t give tractor trajectory the amount of attention that it deserves.
I recommend that you start to develop an awareness for your tractor’s trajectory on Day 1.

While performing a backing maneuver our main concern is usually what is going on behind us. And for good reason. There is a lot to be focused on. It is very easy to forget about the front of your tractor for short periods of time. Forget about the front of your tractor for just a few seconds, and you could find yourself with a preventable accident.

The featured photo shows one of the most common preventable accidents while backing up a trailer.

While backing up your truck you must be disciplined and check your passenger side mirror and front bumper at frequent intervals.
Forget for just a few seconds at just the wrong time, and you could find yourself with a preventable accident.

Be aware that the front end will “swing” to the sides as you turn the steering wheel. The sharper the turn, the wider the “swing”.

Front end swing
The front end will swing around it’s rear pivot point while backing

You can minimize mistakes by incorporating safe Tractor Trajectory into the Set Up. This involves relying more on the Offset Law to create an offset, instead of manufacturing it with a sharp turn of the steering wheel. It also involves becoming acutely aware of your tractor’s trajectory.

A safe Tractor Trajectory is one where the tractor is moving parallel to or away from the Danger Zone.

alley dock set up
Set up with tandems on an acceptable path towards a Tire Target

Where is the Danger Zone?

Anytime you complete a Set Up with an offset between the tractor and the trailer and start backing up, you will have to be aware of the Danger Zone. Everything along the entire passenger side of the vehicle should be considered to be at risk. Especially, while performing a 90 degree, or an Alley dock backing maneuver from a narrow street.

Set up field- Danger Zone
Leave a safety cushion of space between tractor and Danger Zone during Set Up.

You will need to turn the steering wheel in order to follow the trailer into the target space, box, or dock. You can’t turn the steering wheel if you are too close to obstacles on the passenger side of your tractor. The front of your tractor will swing that way as you are backing up and you could easily clip something.

Be sure to always leave a cushion of space between your tractor and the danger zone during set up.

A common theme in your Truck Driver training will be becoming aware of new things. Tractor Trajectory awareness is a must for you to develop and practice. What that really means is always being aware of exactly where the front of your tractor is pointing at all times.

The following tractor is pointing up the middle of the street. Its rearward trajectory is parallel to the Danger Zone. I’ve eliminated the trailer just because I want the focus to be on the tractor here.

Rearward tractor trajectory

When you are performing an alley dock backing maneuver you should be acutely aware of where your tractor is pointing. If this tractor were pointing just slightly left of where it is now, it could spell trouble. It would be on a dangerous trajectory. One that would bring the tractor closer and closer to the danger zone as you backed up.

Be sure when finishing your set up that your tractor is pointing straight up the street or towards the danger zone and that your steer tires are straight.
This will ensure that your tractor is never getting closer to the danger zone as you back up.

This involves taking full advantage of the Offset Law to create the majority of your tractor and trailer’s offset as you back down the street and try to hit your tire target. Experienced drivers have instinctively learned to use the Offset Law to back into an alley dock.

Knowing a small handful of observable properties will help you repeatedly predict how your trailer will behave. With the steer tires straight the trailer will offset from the tractor at a predictable rate. With a little practice and careful observation, you can get a trailer into a dock with very little steering wheel manipulation.

If you want to read an in-depth discussion about this law and its principles you should read my previous post about the Offset Law.

Follow the trailer into the target space gradually. And start earlier!

I recommend that you follow the trailer gradually into the hole with small incremental turns of the steering wheel.

As soon as I notice that the offset is taking place to my liking while looking rearwards, I put a small counterclockwise turn into the steering wheel. Maybe one-quarter of a full revolution, and just hold it. This starts the process of moving away from the danger zone with the front of the tractor. And, with a minimal amount of front end swing. I will observe closely what this does to the speed of the offset. One of the main properties of the Offset Law states that the more offset there is, the faster it offsets further. This will slow down that process, and keep you closer to the front of the trailer. If I notice that it is offsetting too slow, I can turn the wheel back to its previous position and allow the offset to naturally speed up again.

This is better than waiting until the last minute and turning the steering wheel fully counter clockwise. That takes some experience to time correctly. It also makes for a maximum amount of front end swing towards the danger zone.

Use all available space.

Be aware of the gaps between obstacles along the danger zone. I would notice the gap between the black and blue car during my set up. I may want to utilize this gap as a chance to make a steering wheel turn and slow down my offset.

use all available space
The space between these cars is available space.

(Again, I’ve removed the trailer so we can focus on just the tractor’s trajectory)

Once your front end entered the gap you could straighten your steer tires and continue to travel straight back on the current trajectory. This way you would be creating space between your tractor and the danger zone. Once your front bumper clears the obstacles you would be free to make bigger turns with the steering wheel in order to create or eliminate offset as needed.

I do not recommend that you set up to this dock like the truck in the following image.

Dangerous tractor trajectory
Dangerous trajectory with room for a car to pass. Not a good idea.

This tractor is on a dangerous trajectory that is traveling towards the Danger Zone. Secondly, notice that everything south of the blue car’s front end is in a huge blind spot. And finally, there is plenty of room for the red car traveling up the street to try and pass you. They could be distracted and drive right into your path. You would never see it until it was too late. And trust me, if you give people room to get around you, they will try.

Strive to use the intrinsic properties of the Offset Law to create most of the offset between your tractor and trailer when doing a 90-degree backing maneuver.

Always leave a safety cushion of space between your tractor and all of the obstacles on the passenger side of your tractor.

Consider everything down the entire passenger side of your tractor after Set Up completion as the Danger Zone.

Develop an acute awareness for where your tractor is pointing at all times.

Try to keep your rearward tractor trajectory traveling parallel to, or away from the Danger Zone as much as possible. This will help reduce the amount of preventable accidents you have during your driving career.

Stay Safe out there!

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