4 Conditions That Cause Limited Visibility and How to Handle Them
There are only two types of driving environments we can encounter, perfect and not so perfect. We use two terms to describe these environments: ideal and adverse. Visibility is something that refers to the ability to see and be seen. There are a number of conditions that can contribute to poor visibility while driving. Do you know how to safely address them?
What Causes Limited or Poor Visibility?
- Time of day. Too much sun or not enough sun can play tricks on the most experienced drivers. Combine rush hour with glaring sun and you’ve got a dangerous mix. The most dangerous time of day to drive is between 5:00 and 7:00 p.m.
- Weather conditions. Dicey weather conditions like heavy rain, snow or fog are less than optimal. All drivers, even novice drivers, quickly learn that they must be sensitive to deteriorating weather conditions. When confronted with adverse weather, determine if the trip is absolutely necessary or if it can be delayed.
- Direct obstructions to your view. From a dirty windshield/windows to overgrown vegetation along the roadway, all can block your view and line of sight, inhibiting your ability to see well.
- Poor roadway design. Abrupt roadway ramp exits and entrances or sharp turns on curves or hills contribute to limited visibility. One of the most important skills a driver can have is the ability to analyze the driving environment.
How to Address Obstacles to Your Visibility
- Scan ahead to anticipate potential hazards and turns. Don’t be forced into making an abrupt maneuver at the last moment! Remember, the average reaction time for drivers is 3⁄4 of a second. Allow yourself enough time to identify the hazard and a plan of avoidance.
- You should also adjust your speed to account for poor road conditions. Speed limits are posted for the ideal conditions, not adverse conditions.
- Be smooth and precise when braking, accelerating, and turning to avoid excessive weight transfer.
- Perform regular maintenance on your vehicle. Keep your windshield washer fluid reservoir full and ensure your headlights, wipers, and defroster are all operational.
- Increase following distance — there is no need to tailgate. Even if your vehicle is equipped with an anti-lock braking system (ABS brakes), you must still increase your following distance.
- Turn on low beams in the rain and/or snow. Using your low beams whenever you use your windshield wipers is required in Illinois.
- Always avoid driving impaired (drugs, alcohol, sleepy, etc.).
Helpful Acronym for Successful Driving (STV)
When matching or adjusting your speed for poor conditions or limited visibility, you must evaluate three key elements: space, traction and visibility (STV).
- Space quite literally refers to the area around the vehicle. Some examples of things that could affect our space would include: width of lanes, size of vehicles, debris in the roadway, parked vehicles, pedestrians, bicyclists, etc.
- Traction accounts for the grip of the tires to the road surface. Rain, snow tread wear, improper inflation, speed and road surface all affect tire traction.
- Visibility, as described earlier, pertains to what you can and cannot see around you.
Interested in taking an adverse weather course with Top Driver? Click here to register! This refresher course is only $15, online and self-paced.
Frequently asked questions
What are the most common conditions that limit a driver's visibility?
Four conditions cause the bulk of visibility problems on the road. Time of day plays a major role, especially low sun angles during sunrise, sunset, and rush hour. Weather, including heavy rain, snow, and fog, dramatically reduces how far ahead you can see. Direct obstructions such as a dirty windshield, fogged glass, snow on the hood, or overgrown roadside vegetation block your line of sight. Finally, poor roadway design, like abrupt ramps, sharp curves, and blind hills, hides hazards until the last second. Recognizing which condition you're driving in is the first step to adjusting safely.
What time of day is the most dangerous to drive?
The hours between 5:00 and 7:00 p.m. are statistically the most dangerous time of day to be behind the wheel. That window combines heavy rush-hour volume with low sun angles that can blind drivers, plus the fatigue that builds up by the end of the workday. Even experienced drivers get caught off guard by glare during these hours. If you're driving during evening rush, give yourself extra following distance, keep your windshield clean inside and out, and have sunglasses within reach.
What does the STV acronym stand for in driving?
STV stands for Space, Traction, and Visibility, and it's the framework Top Driver instructors teach for adjusting your speed in less-than-ideal conditions. Space is the area around your vehicle, which is affected by lane width, vehicle size, debris, parked cars, pedestrians, and cyclists. Traction is the grip between your tires and the road, influenced by rain, snow, tread wear, tire inflation, speed, and surface type. Visibility is what you can and cannot see around you. When any one of the three is compromised, slow down and increase your margins.
Are you required to turn on your headlights when it rains in Illinois?
Yes. Illinois law requires drivers to use their headlights whenever the windshield wipers are in use. Stick to low beams in rain, snow, or fog. High beams reflect off precipitation and actually reduce what you can see. Headlights also make your vehicle more visible to oncoming drivers, which matters most when visibility is poor for everyone on the road.
How much following distance should I leave in bad weather?
Increase your following distance whenever conditions deteriorate. Posted speed limits assume ideal conditions, not adverse ones, so the standard three-second gap is no longer enough. The average driver reaction time is about three-quarters of a second, and that's before braking distance is added on wet or icy pavement. Even cars equipped with anti-lock brakes need more room to stop in rain or snow. Don't tailgate, leave a generous cushion, and brake, accelerate, and steer smoothly to avoid weight transfer that can break traction.
What pre-trip vehicle checks help with visibility?
Visibility starts with the vehicle, not the road. Keep your windshield washer fluid reservoir topped off, and make sure your wipers, headlights, taillights, and defroster all work before you leave. Clean both sides of the windshield, mirrors, and headlights, since road film cuts down on light dramatically. Replace wiper blades when they streak. If you can't see clearly through every piece of glass and the defroster won't clear it, don't drive. A two-minute walk-around prevents most visibility surprises.
