European legislation again leads the way in ensuring adequate visibility, and this has carried over into North America. "Europe instituted what they call a 1 meter by 1 meter," says Monical. "That regulation states that anything that is 39 inches tall should be visible within 39 inches of the machine, all of the way around it. So the top of a 1-meter stick has to be visible by the operator in the operator's seat within 1 meter of the machine, all the way around."
This has transformed the shape of compactors from a brick to the tapered shapes we now see. "All manufacturers have made that change or are in the process of making that change," says Monical.
Manufacturers have also built in greater flexibility for positioning the operator on the machine. For example, all modern tandem drum rollers feature a sliding or rotating operator platform, Meyer points out.
Rotating and sliding cabs offer even better visibility for the operator. "It is critical that we get the operator the best visibility we possibly can," says Gallant. "It does add some expense. But generally, we have found that operators are willing to pay the extra expense to get the visibility they need to do the job, especially in the asphalt field."
HAMM showcased its DV Series asphalt roller and Ingersoll Rand displayed its DD-158HFA roller at CONEXPO-ConAgg 2005. Both have rotating and sliding cabs.
Consider operation of the HAMM DV Series. "The seat rotates 360 degrees and slides left or right inside the cab," says Monical. "And the cab slides left or right off of the side of the main frame."
In North America, center-pivot rollers are still the norm. But in Europe, the rigid-frame models - with drums that pivot independently to steer and allow for sliding cabs - have become more prevalent.
Electronics have allowed the automation of several functions on the newer rollers. But there are different schools of thought on how much you should actually automate.
"We have automated certain functions, but others we are leaving manual," says Gallant. "We are offering operator choice by design because we don't feel the machine should be making those choices. This allows the operator to make critical decisions about how the compaction is performed in any given application."
Ingersoll Rand has used automation to reduce the number of actions required by an operator in a given pass. For example, the company offers automatic vibration cutoff, drum sequencing and a system to control water flow. "As the operator slows down, the vibration shuts off at a certain threshold," says Gallant. "As he speeds up on his next pass, it turns on." The operator doesn't have to remember to turn the vibration on and off. When the travel direction is changed, the drum eccentric rotation correspondingly changes direction. And the flow of water increases and decreases as the travel speed of the roller increases and decreases.
"We also govern the speed of the machine with automated speed control for proper rolling speed when working for proper impact spacing," says Gallant.
Other manufacturers have taken machine automation to a level where the operator may simply be asked to drive the machine in a straight line. For example, HAMM offers an electronic control system that allows you to pre-program the machine to run at a certain ground drive speed, and speed up or slow down its vibration depending upon the density of the soil that is registering through a feedback sensor in the drum.
Another aspect of the electronic control system is traction control. "Anti-slip controls enable the machine to move traction from the drum to the tires or the tires to the drum to improve the ability to climb a slope," Monical explains. "It is a semi-safety factor and certainly an improvement in the efficiency and proficiency of the machine."
These systems reduce the skill level required of the operator. "The whole system is designed to make the machine more efficient and to take more concern away from the operator as to exactly what is going on," says Monical. "His only concern is with driving in a straight line."
Ergonomics are also playing a larger role in roller design. "Enhanced roller ergonomics is one of the many ways manufacturers are improving the technology of rollers today," says Meyer. "A roller operator is no different than anyone else. We all desire a comfortable work environment. A well-designed operator's platform will provide a reasonable level of comfort and keep controls within easy reach."