It's certainly arguable but the case can be made that the roller operator is the most important member of the paving crew. Why? Because he is the person who puts the finishing touch on all the preparation and paving work that went before him, and he is the person who makes sure the paving contractor gets paid (and in some cases how much the contractor gets paid).
One contractor I work with describes the roller operator's job in his employee manual, saying the roller operator is "?responsible to achieve a quality finished product with special attention to meeting the compaction and aesthetic requirements of the job." That about sums it up. He is responsible for achieving density requirements on jobs that have them, ride specs on jobs that have those, and he's responsible for a smooth and line-free mat as well as basic hot mix asphalt compaction requirements on every job the paving contractor does.
At the same time the paving crew has to realize the roller operator is not a miracle worker. He can't fix problems caused in laydown and he can't repair defects caused, for example, by a damaged screed. If the mat is not laid properly or if the screed has lines in it, for example, the roller operator is not going to be able to fix that. He can only provide a good finish to what he's given, and that's all a good roller operator wants: the best opportunity to provide the best finish.
Rolling over the years
The "old timer" roller operators used to say they could feel everything they needed to know about the mat and their job through the seat of the roller. And there might have been some truth to that given that the seats were steel and the rollers themselves were unsophisticated pieces of equipment with no bells or whistles to make them easier to use, more comfortable to operate, or more effective in the asphalt mat.
But it's not true anymore. Today's rollers are very comfortable, with seats and operators "isolated" from the machine, and they have become very sophisticated with joystick controls, fine-tuned steering, articulation, and any number of gauges and dials operators can use to make their job easier and help them perform better.
Today's roller operator needs to be able to roll by more than just the seat of his pants. So today's roller operator needs to have a complete understanding of the piece of equipment he's using, the gauges he can follow, as well as what the roller can and cannot be expected to do.
Gauges are a perfect example. Years ago roller operators would guess at their speed, often by eyeballing the distance between the roller and the paver and trying to maintain that distance. But today's rollers offer miles-per-hour or feet-per-minute gauges that tell the operator exactly how fast he's moving. That's important because the operator wants to move evenly over the mat, maintaining the same speed up, the same speed back, the same speed up, and the same speed back, to provide even compaction, and the gauges make it easier to do that. Keeping an eye on those gauges makes it easier to stay consistent.
What a roller operator needs to know
Just like the paver operator and the back-end operators, the roller operator needs to know all the details about the job. He obviously needs to understand basic rolling and compaction concepts, but that's just the start.
He needs to know where paving will start, how it's going to proceed, what position he's rolling in (breakdown, intermediate, finishing) and the responsibilities for that position. Mix information is also crucial. What kind of mix design is the job using? What is mix temperature (and air temperature)? What size mix is it (3/8 in. on a driveway or 3/4 in. on a highway)? Is it a more stringent mix? Is it a tender mix? What is the mat thickness? Is there a crown? What are compaction and density requirements? What is the speed and width of the paving?