Research: Snowplow Operation

Forward Lighting

To minimize distraction and potential for glare caused by snowplow forward lighting, previous research on visibility and atmospheric optics suggested that two solutions could be used to minimize the amount of light reflected back from snow, rain, and fog particles in the air:

• using narrow-beam lamps
• mounting lamps as far from the driver's line of sight as possible

Narrow-beam lamps produce a smaller cone of light, which in turn will illuminate a smaller area of falling snow, rain, or fog in front of the snowplow vehicle. Mounting position of the lamp is important because the amount of light that is reflected from snow, rain, or fog has been shown by previous researchers to be inversely related to the distance d from the line of sight. This distance is shown in the sketch below.

This factor is especially important for snowplows because the front plow blocks the standard truck headlamps, so that auxiliary headlamps must be used. These lamps are raised above the plow so that the driver side headlamp is very close to the snowplow operator's line of sight. This positioning results in the greatest amount of back-reflected light.

To test these findings, lamps having two beam widths were mounted on snowplows in several locations as noted below (A through D). Position B was closest to the operator's line of sight, while Position D was furthest. Snowplow operators plowed while using each of these lights and, as expected, gave the highest ratings of visibility and preference to the narrow-beam lamps in Positions C and D and the lowest to the wide-beam lamps in Position B.

Based on these results, the use of narrow-beam lamps mounted on the passenger side of the snowplow is recommended to minimize back-reflected light during snowplowing operations in poor weather.