Henry Peter, general foreman, Cranston Highway Department, uses the simulator to "drive" a snowplow during a snowstorm.

The Providence Journal / Kathy Borchers

WARWICK — Imagine a triptych with computer screens replacing the triple folding panels of painted wood employed by medieval artists.

And ponder hurtling down a dark highway in a loaded dump truck, dodging obstacles and encountering disorienting changes in the weather.

It’s all smoke-and-mirrors, or at least the electronic version of smoke-and-mirrors trying to channel reality. It’s a “truck simulator” that the state Department of Transportation and the University of Rhode Island’s Transportation Center will be using to train DOT drivers, police officers, firefighters and other state and municipal workers. The DOT demonstrated the simulator Tuesday at its maintenance facility on Lincoln Avenue.

The cockpit of the device nicely mimics a real bus or truck cabin, complete with a driver’s seat, a gearshift lever, clutch, gas and brake pedals, speedometer and other instruments, and side windows with rearview mirrors.

Off to one side, at a computer, sits David Ferreira, a technician from URI and a man who wields power of which the rest of humanity can only dream — he can change the weather at will, á la the holodeck on Star Trek, the New Generation.

Ferreira taps the keyboard. In a blink, the screens half-encircling Henry Peter, general foreman of the Cranston Highway Department, shift to a winter scene. Crescents of crusted snow on the unswept part of the windscreen add an authentic match to the blizzard raging outside. Ferreira can conjure rain, or flick between day and night. He can summon lightning. He can even cause pedestrians to saunter with little concern into the path of the vehicle, or summon barking dogs that threaten to dart into the roadway.

The feel of the cabin is both real and unreal. There are no G-forces on a left or right turn, or on braking or accelerating, but when the vehicle (Take your pick — Ferreira can transmogrify the conveyance from a school bus to a dump truck to a fire engine to a police car and so on) goes over a manhole cover, the seat actually jolts upward. Ditto for curbs. The steering wheel shudders at ruts. The steering itself is sensitive — more so than on an actual truck or bus. The vehicle veers rapidly in a turn, but, confusingly, there is no sensation of lurch.

Verity is soldered in by the hiss of air brakes, the roar of the engine and the occasional screech of tires trying to stop in a hurry.

Doug Reese, director of public works for Hopkinton, takes a turn, unluckily just after a reporter had asked Ferreira whether collisions occur.

Ferreira waves his wand. A police car, siren screaming, flashes across the bow of Reese’s car, impossible to evade. “Collision” glares across the splintered windshield of Reese’s car, which spins out of control and belts a formidable stone church with admirable force, a triumph greeted with hearty applause from a dozen or so onlookers.

Reese’s comment after the smashup? “It’s a different sensation when you are driving.”

Ferreira said no one has actually freaked out while operating the simulator, but “some people can’t handle it because it can make you nauseous.”

He explained that when the simulator morphs into a snowplow, “you give it the gas quick, and the front of the truck lifts up. If you keep doing that it screws up your balance a little bit because you are seeing something that you are not feeling. It’s called SAS, or simulation adaptation syndrome. That’s when the mind has conflicting inputs from two or more senses. It’s basically that your eyes are relaying a sense of movement to the mind, but the body does not experience any G-force.”

One segment of the population seems to be immune to SAS — the generation that grew up playing electronic games while seated in front of a TV screen.

“The younger kids don’t have any problems with it,” Ferreira said. “It’s more an adult thing.”

tmorgan@projo.com