Gene Schimmele’s striping crew has four trucks: a paint truck and three stock trucks. On the job, they move in caravan.
Two crew members work the paint truck itself. Nam Ly drives. In the back cab, Bob Leary fills the role of what everyone calls the “button pusher” (official title: console operator). They communicate by headset.
Leary and Ly can work from either side of their cabs; if they’re painting on the right, that’s the side they’re on (and vice versa).
How fast they drive actually determines the thickness of the stripe. Ly has cruise control and a digital speedometer to maintain the correct speed, down to the tenth of a mile per hour. For a 15-mil stripe, which is a typical thickness, the paint truck travels 12 miles per hour.
At the controls
Even though it’s the console operator who sprays the paint, it’s the driver’s skill that determines the accuracy of the line. “The better he is, the better the line looks,” Leary says.
To help the driver stay in a straight line, a guide wheel extends from the front of the truck. “Where the wheel goes, that’s where Bob lays down the paint,” Ly says. “If I wiggle, you’ll see it in the line. You try to run the wheel on the line, but not stare at it.”
On curves and turns, it takes more teamwork to keep the line on track. “You have to get used to working together,” Ly says.
In the rear cab, the “button pusher” controls the paint and nozzles. Epoxy is more challenging than latex. It’s a two-to-one mixture of paint and catalyst. Leary must keep temperatures and pump pressures within a narrow range to make the formula work.
Leary monitors several consoles of switches, dials and gauges, including the type of stripe the truck will paint: a solid line for the edge; a dashed line, or “skip,” between lanes; or even shorter “cat tracks” for lane mergers and other special situations. “You don’t want to mix them up,” Leary says, “though we’ve all done that once or twice.” The distance between skips is programmed automatically.
As the truck creeps along, a high-pressure air nozzle blasts away dirt, debris and even loose paint from the existing stripe. Then the paint nozzle lays down the line – typically four inches wide. Immediately behind it, a separate nozzle blasts tiny glass beads into the fresh paint. The beads are the most important part of the process: They give the stripe its reflectivity, which allows motorists to see their lane in the dark.
Winds can play havoc with the line – blowing paint out of alignment or applying beads unevenly, which diminishes their effectiveness. Toggles, dials and a hand crank help the operator control the height and direction of the nozzles and paint carriage itself.
Godfrey actually invented bead guns that allow the operator to adjust the stream of beads up, down, left or right to compensate for wind conditions. Otherwise, the operator has to hang out the cab window to adjust angles manually. As far as the crew knows, no one else has created or uses anything like it. “I should patent it,” Godfrey says.
There are no dry runs
Behind the paint truck, the stock trucks play several roles. They haul supplies, run blocking maneuvers, and create a safety zone for the paint truck.
The stock trucks – with their presence, warning signs and cones – also create a barrier that discourages motorists from driving over paint before it dries. (Nonetheless, the state pays about 80 claims a year from drivers whose vehicles suffer paint damage.)
The hotter it is, the faster paint dries. At 100 degrees, yellow epoxy can dry to the touch in 45 seconds. When pavement temperatures drop to 60 degrees, however, it takes 5-8 minutes. (White paint, as a rule, takes longer to dry.)
Temperature is the main reason crews usually start their season in southern Minnesota. They head north as the weather warms, then head back south in fall. In July, the crew typically paints metro highways.
They pick the hottest month of the year so they can paint at night, which minimizes their impact on traffic. “This year, we had that shutdown, so the Cities didn’t get painted,” Schimmele says. “That was a problem.”