Truck Length

Last Edited: July 23, 2017 // by TruckerScape, Inc.

Turning

The most obvious characteristics of my truck are its size and weight.  Total length of my tractor trailer is about 73 feet.  This is without the folding/unfolding spoiler (also called “trailer tail” or “wings”) that is attached to the rear of some of the trailers I tow.  The deployed spoiler adds about 4 feet to the total tractor trailer length.  When making any turn the tandems (rear wheels) on my trailer will not follow the same line as the steer and drive wheels on my tractor.  They will track a significant number of feet to the inside of the line made by my tractor.  The amount of inside tracking (“off-tracking”) depends on where my tandems are set and how sharp my turn is.

My trailer tandem axles are attached to rails on the underside of the trailer.  The tandems can be moved back and forth under the rear section of the trailer to balance the weight of each different freight load between the tandems and the tractor’s drive wheels and steer wheels.  The farther forward the tandems, the less pronounced the off-tracking.  Tandems forward is especially useful when I’m in tight quarters in a shipper’s or receiver’s yard or on a narrow, congested city street.

In a shipper’s or receiver’s yard I may make a turn so sharp that my trailer essentially pivots on its tandems—in this case the off-tracking is nearly the length of the trailer.  Turns on surface streets are not that sharp, but off-tracking on right turns past street corners and on left turns past opposing traffic can still be a challenge.  You will see me swing wide in the tractor to minimize encroachment.

When there are two or more turn lanes through an intersection, I will try to get in the outside lane and swing wide to obstruct traffic as little as possible.  Most of the time, such turn lanes are shallow enough for traffic to turn alongside me on the inside lanes.  If you are alongside my tractor or the front of my trailer you are in the best position.  If you are toward the rear of my trailer, you may want to let my trailer pass you, to make sure you are not crowded out.

I check for vehicles inside my lane in left turns, but I also depend on you to watch closely and use your judgment.  It is wise to assume that you are not visible directly or in my mirrors when alongside my truck during right turns or in an outside lane during left turns (also see the Vision tip in this chapter).

Roundabouts

Roundabouts are being built as a purportedly less expensive and more efficient alternative to conventional four-way-or-more intersections controlled by traffic lights, stop signs and/or yield signs.  Roundabouts require less maintenance and except in cases of extremely heavy traffic, should promote freer and better flow.  They require more real estate than conventional intersections, especially if they have more than one lane.  Their radius has to be sufficiently large so the curvature of their lane(s) is shallow enough to enable trucks to safely negotiate them (ideally to track within one lane).  So I have found them primarily in less densely populated areas, generally west of the Mississippi River.

Since we drive on the right side of the road in the U.S., the direction of traffic in roundabouts is counterclockwise, or to the left.  This helps truck drivers, because the centers of roundabouts are on our left (“sight”) side where we can monitor our off-tracking trailer tandems from our driver’s side windows and mirrors.  On smaller, tighter single-lane roundabouts I crowd the lane’s outside (right) edge to get my trailer around the center island without running into it.  Most roundabouts have an apron (a slightly raised sidewalk-like safety shoulder) around the island that off-tracking tandem tires can roll over.

On multi-lane roundabouts I try to drive in the outer lane and again crowd the outside edge in order to avoid encroaching on the path of any vehicles travelling alongside my truck in the inner lanes.  I may or may not be able to keep my trailer entirely within the outer lane, so you should be cautions when in the roundabout with me.  It’s always safer to stay behind my trailer instead of getting alongside any section of my truck.

Driving in one of the inside lanes is problematic for me for two reasons:  First, it’s more likely that my trailer tandems won’t track entirely within that lane.  Second, vehicles in the outer lane(s) to my right are on my blind side, so it’s problematic to safely steer, even minimally, into their lane(s) to correct my trailer tandem tracking.

Obviously in such a long vehicle, lane changes, passes and parking are more complicated than in a car or pickup truck.  We will discuss these maneuvers in detail in later chapters and tips.

Takeaways

It is safest to stay behind a truck on a roundabout or when it is making a turn at an intersection.

Allow for off-tracking when alongside a truck in an inside lane on a roundabout or in an inside lane in either a left or right turn at an intersection.

Assume that you’re out of the driver’s sight and stay cautious when you’re alongside a truck in an outside lane in a roundabout.

Assume that you’re out of the driver’s sight and stay cautious in an intersection when alongside a truck in either inside or outside lane during a right turn or in an outside lane during a left turn.

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