The Peterbilt Model 579 retrofitted with the PlusDrive Level 2 autonomous control system awaits...

The Peterbilt Model 579 retrofitted with the PlusDrive Level 2 autonomous control system awaits another test drive on the freeways around San Jose.

Photo: Jack Roberts

There I was, in midday traffic, on a freeway in San Jose, California, behind the wheel of a fully loaded Peterbilt Model 579 tractor-trailer. But I wasn’t driving the truck.

To be clear, I was in charge of the truck — making all the usual, mundane, second-by-second decisions that we all do: Stay in this lane? Move over a lane? Is this my exit ramp? And so on. But the actual work of carrying out those commands: steering and holding the truck in its lane, maintaining a safe highway speed, managing intervals between other vehicles, watching traffic ahead and behind the truck, handling dicey California merging lanes, and actually making a lane change when I decided one needed to be made, was all being handling by the PlusDrive autonomous control system. All I had to do to keep PlusDrive alert, awake and engaged was to let the system know that I was there, behind the wheel and keeping an eye on things every 15 seconds.

What I experienced on that drive convinced me that Level 2 safety systems, like PlusDrive, will be a standard safety spec on new Class 8 tractors just a few short years from now. I predict the adoption rate will mirror what the industry saw when automated transmissions took off — the take rate is going to look like a hockey stick.

The “Plus-Minus”/accelerate/decelerate button on the far right both activates Plus Drive and can...

The “Plus-Minus”/accelerate/decelerate button on the far right both activates Plus Drive and can be used to confirm that you are still in the seat, alert and monitoring the drive while engaged.

Photo: Jack Roberts

What is Autonomous Trucking?

Most of us have a certain vision of “autonomous trucking” in our heads. It’s the idea that an “autonomous truck” will be a machine that operates totally on its own out in the world with little or no human interaction to guide it to its destination — a “driverless truck.”

That perception is correct for Level 4 and Level 5 autonomous control systems. But we are still years away from viable Level 4 and Level 5 systems operating trucks in widespread everyday fleet operations.

Level 2 automation as defined by the Society of Automotive Engineers, what it calls “partial driving automation,” is available today. Freightliner was the first to announce Level 2 automation back in 2019 with the Detroit Assurance 5.0 with adaptive cruise control and active lane assist. Plus is selling its Level 2 PlusDrive system to fleets today, and it’s brand-agnostic.

The benefits and capabilities offered by a “mere” Level 2 autonomous system are astounding to experience first-hand. That’s because PlusDrive is designed to 100% help and support drivers. That’s its mission in life. PlusDrive isn’t about making big decisions about how to get from Point A to Point B. Its focus is far more granular and immediate, such as steering, holding the lane, the speed, and so on. The human in the driver’s seat decides things such as what route will be taken, if a lane change is necessary, and where to pull over for the night. When engaged, PlusDrive is there strictly to help out by "watching" the front, side and back of the truck, maintaining a safe speed and steering.

All you have to do to keep it on the job is exert some positive pressure on the steering wheel, or alternatively, tapping the “engage” button on the steering. As long as PlusDrive gets positive confirmation every 15 seconds that you’re still in the driver’s seat, keeping an eye on things, it stays faithfully on the job.

Plus sensors are located around the truck, including on the rear-view mirrors. Here you see a...

Plus sensors are located around the truck, including on the rear-view mirrors. Here you see a lidar sensor at the bottom of the mirror, with a side-facing camera mounted above. A rearward-facing camera (not shown) is mounted at the top of the mirror assembly.

Photo: Jack Roberts

Safety First, Fuel Economy Second

I first drove PlusDrive in May on a brief run around Long Beach, California, during the Advanced Clean Energy Expo. With me on both drives was Plus truck operator Guztavo “Gus” Martinez and Associate Producer Keven Duong.

PlusDrive is remarkably simple to learn. But, in the interest of safety, Martinez gave me a quick refresher on its features. Then we were off onto the famous 101 Freeway.

By my standard, the highway was pretty busy for a weekday mid-morning (although Martinez and Duong kept wondering where everybody was.) Still there was plenty of traffic to test Plus Drive’s capabilities on a fairly chaotic public road.

PlusDrive is designed for freeway driving. The system cannot be engaged in urban traffic conditions or on freeway on-ramps or exits. Human control is mandatory in those situations.

But once I was merging onto the 101 and the Plus sensors around the truck determined that I was in a safe freeway setting, a message flashed up on the center console display screen letting me know that the system was available and ready to be engaged.

Doing so is simple. PlusDrive is a retrofit system that uses the cruise control mounted on the steering wheel. To go into autonomous mode the driver takes a foot off of the throttle and hits the + or “Plus” (accelerate) button on the steering wheel twice. Immediately, a message confirming engagement flashes on the display screen and the truck begins to drive itself down the road.

At this point, PlusDrive is handling pretty much every detail in keeping the truck in the flow of traffic and adjusting speed as needed according to conditions. Control is precise enough that when in the right lane, with a stalled vehicle or work crew on the shoulder ahead, it will jog out slightly and put the front tire on the left-side lane marker to give those vehicles a safer amount of space when it passes them.

Initiating a lane change is as simple as clicking the turn-signal stalk left or right twice within three seconds. Immediately, PlusDrive begins tracking oncoming vehicles in the selected lane, looking for a safe interval in which to move over. The display screen shows exactly what the system is doing, with the selected lane flashing red until an opening appears. The lane graphic then immediately turns green and, in Martinez’s words, the system “goes for it.”

If traffic slows down to a crawl — something that seems to happen about every five minutes on a California freeway — PlusDrive immediately decelerates the truck and maintains ample following distance.

Plus designed the system to prioritize constant motion whenever possible in the interest of fuel economy. As we all know, diesel truck engines burn more fuel during the lower parts of the torque curve as they toil to get heavy trucks up and moving from a dead stop. Even a little bit of forward motion goes a long way toward mitigating that low-end fuel burn. So PlusDrive will not come to a complete stop unless it absolutely has to.

This approach works well in real-world driving conditions. The truck pokes along, while never stopping, giving the mass of vehicles up ahead additional space and time to get themselves sorted out. Once traffic picks up, PlusDrive applies the throttle and gets you back to up to your cruise speed/fuel economy sweet spot as quickly and efficiently as possible.

The system never exceeds the posted speed limit. There is a small window for higher speeds, however. You can engage PlusDrive at 58 mph in a 55-mph zone, for example. But you cannot engage it at 60 mph until you get your speed back down into the system’s safe-activation range.

How PlusDrive Handles Merging Lanes

The Plus engineers and designers are particularly proud of the way the system handles chaotic merging systems. For starters, each merge lane is geofenced as a “caution area” by the system. PlusDrive always slows down for safety in merging areas, even if no other vehicles are in its immediate vicinity. When traffic is merging, the truck immediately slows to a crawl and lets traffic merge in front of it, all while maintaining safe, steady forward momentum. Once it reaches a point where a tracked vehicle no longer has the room to get in front of the truck and merge, it accelerates and reclaims its lane. Plus designers say that giving the merging vehicles plenty of room to move onto the freeway, while maintaining forward momentum, actually reduces congestion and stop-and-go traffic. During our drive, even in highly intense, congested merging areas, the truck never once came to a complete stop.

The most difficult aspect of managing a truck while PlusDrive is engaged is letting the system know that you’re still there. Because the system is designed to hold the center of the lane you’re in, it tends to cant slightly left or right, depending on the wind or the lateral slope of the roadway. Martinez told me he usually holds constant pressure on the wheel opposing that cant – which is enough to let the system know you’re there. Deliberate or aggressive wheel movements aren’t necessary, although that’s what drivers new to the system tend to do at first. An alternative option is to simply push the activation button on the steering wheel once every 15 seconds. Toward the end of the drive, my confidence in the system had grown so much that my only contact with any control system on the truck was my right index finger resting lightly on the “Plus” button while the steering wheel twisted left or right beneath it. I’d tap the button every few seconds to let Plus Drive know I was there. And that was my total contribution to physically controlling the truck while it cruised down the highway.

I’ve said in the past that PlusDrive and other automated systems focused on complementing driver performance and safety are like conventional cruise control on steroids. But after experiencing PlusDrive, I think a more apt description would be a conventional cruise control system transforming into the Incredible Hulk. That’s how powerful it is. I believe the safety benefits they offer fleets and drivers are that transformative.

The Society of Automotive Engineers describes Level-2 autonomous systems as “partial driving...

The Society of Automotive Engineers describes Level-2 autonomous systems as “partial driving automation.”

Graphic: SAE

Autonomous trucks are coming. There is no question about that. But truck drivers will still dominate this industry for many years to come. Which is why I think systems like PlusDrive, which help those drives stay more alert and be safer, will soon be a no-brainer spec for any fleet interested in safety and fuel efficiency.

Originally posted on Trucking Info

About the author
Jack Roberts

Jack Roberts

Executive Editor

Jack Roberts is known for reporting on advanced technology, such as intelligent drivetrains and autonomous vehicles. A commercial driver’s license holder, he also does test drives of new equipment and covers topics such as maintenance, fuel economy, vocational and medium-duty trucks and tires.

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