Snowplow Science
Copyright 2004 by Edward Willett
There’s nothing like a good blizzard to bring home to Canadians the importance of that otherwise seldom-heralded piece of technology known as the snowplow.
The first highway snowplows were developed early in the 20th century, shortly after there were enough automobiles around to require them. (Michigan claims to have created the first snowplow in the U.S.–two wooden wings mounted on a truck’s running boards; I couldn’t find any reference to Canada’s first snowplow.) Today’s state-of-the-art snowplows feature things like heated windshields and mirrors and aerodynamically sloped hoods (for better visibility, one presumes, not speed), but are really just refinements of those initial low-tech plows.
But that may be changing.
The hotbed of snowplow research (if that isn’t a contradiction in terms) is the Intelligent Transportation Systems Institute (ITSI) at the University of Minnesota. There, scientists are trying to enhance safety for the operators of snowplows and other vehicles, such as police cars and ambulances, that have to routinely navigate icy roads in reduced visibility without either sliding into the ditch or running into something.
Two focuses of ITSI research are vision enhancement and collision avoidance. The vision-enhancement system under development allows drivers to “see” in low-visibility conditions by projecting computer-generated road markings onto a transparent screen mounted close to the windshield. The computer-generated markings are overlaid onto the driver’s view of the actual. road. In a photo of the system at work, strips of light overlay an otherwise almost-invisible night-time roadway, revealing an otherwise hidden oncoming curve. (Another element being tested as part of the system is a “virtual rumble strip”–the driver’s seat vibrates when the vehicle has gets too close to the edge of the road.)
The system combines highly accurate digital road maps with Differential Global Positioning Satellite technology (which compares signals between a stationary, base GPS station and a GPS receiver on the moving vehicle to enhance the accuracy of the location information).
Minnesota snowplow drivers have used the test system to safely drive a snowplow in zero visibility (created by hanging curtains over the windows). Minnesota State Troopers have also tested it; they liked it, but noted it would require special training to use safely, because the temptation is to focus exclusively on the HUD display and stop scanning the road ahead as you normally would, which would be bad news if the road included an unanticipated obstacle such as a stopped car.
Of course, avoiding such impending collisions is where collision-avoidance technology comes in. Laser sensors detect if there is something ahead or to the side that’s getting too close and issue a warning. (In one test, the Minnesota researchers determined that drivers responded most quickly to a double-beep, like a car horn, to warn of an impending side collision and to two bursts of tire-screeching sounds to warn of an impending front collision.)
Of course, the most common accidents involving snowplows are cars rear-ending them. In Saskatchewan, for example, there were 12 such accidents involving snowplows on Saskatchewan highways between 1999 and 2002.
Saskatchewan snowplows have large “wig-wag” lights (lights that flash back and forth) on their rear ends as a warning to following motorists. Recent research at the Lighting Research Center at Rensselaer Polytechnic Institute in New York, however, found that bright, steady-burning light bars mounted on the rear of a snowplow improve drivers’ ability to detect the snowplow’s relative position and speed, compared to flashing or strobe lights.
Some snowplow research is aimed at enhancing efficiency. Another project in Minnesota uses GPS technology to measure both the forward and side-to-side movement of the vehicle. A computer programmed with known principles of vehicle dynamics can use that information to calculate the friction coefficient of the tires–in other words, how slippery the road is. The system has worked well in tests.
Having this information would allow road maintenance workers to spread sand and salt where they are most needed. But there are potential benefits for many other types of vehicles, including, perhaps, passenger cars, which could adjust their own anti-skid systems according to the road conditions, issue a warning to the driver, or even adjust or disable cruise control. Similarly, snowplow vision enhancement and collision-avoidance systems may also find their way onto other types of vehicles in the future.
But by all means, let the snowplows have them first. As long as the snowplow drivers can do their difficult jobs safely and effectively, the rest of us can muddle along. But without the snowplows, we’re stuck.
Literally.
