Here are some headlight safety tips, culled from the Minnesota Driver's Manual. You may want to pass along this advice to your fleet drivers as a reminder.
When you're within 1,000 feet of an oncoming vehicle, or following another vehicle at a distance of 200 feet or less, your headlights must be set on low beam. Your headlights must be turned on at sunset and used until sunrise. They must also be used during weather conditions that include rain, snow, hail, sleet, or fog and any time you cannot clearly see the road ahead for a distance of at least 500 feet.
Don't "overdrive" your headlights. You should be able to stop within the distance that your headlights illuminate the road. For most vehicles, this distance is no more than 350 feet on high beam.
When driving in the dark, you may encounter glare from oncoming headlights or from the reflection of headlights in your rearview mirror. If you are blinded by the glare, use the white line along the edge of the road as a reference. For glare caused by headlights from behind you, use a "day-night" mirror or re-adjust your regular mirror.