What is the function of a car's width indicator light?

[VanMila]

The function of a car's width indicator light is to indicate the presence and approximate width of the vehicle, facilitating judgment for other vehicles during passing and overtaking. Installed at the edges of the car's roof, these lights indicate both the height and width of the vehicle. Safety regulations require vehicles taller than three meters to be equipped with width indicator lights, which are white at the front and red at the rear, ensuring visibility to other vehicles during nighttime driving. Additionally, fog lights are commonly installed near or slightly lower than the headlights. Used in conditions of low visibility such as fog, snow, heavy rain, or dust, they serve as road illumination and provide signals to oncoming traffic. Fog lights typically emit yellow light with longer wavelengths, offering excellent fog-penetrating performance.

[SanFelix]

I often drive long distances, especially on highways at night, where the role of side marker lights is crucial. They illuminate the sides of the car, such as the small lights near the front and rear lamps, clearly marking the vehicle's width and position. This way, in darkness, fog, or rain, other drivers can see the size of my car from afar, avoiding misjudging distances or accidental collisions. Once, while driving on a foggy mountain road with poor visibility, I relied on these side marker lights to maintain a safe distance from other vehicles, preventing potential accidents. I also recommend regularly checking if the bulbs are burnt out, as sudden failure could pose risks. When parked on the roadside, I keep them on to alert pedestrians, but remember to turn them off to save battery. These small details genuinely enhance driving safety.

[DiAllie]

As a city commuter, I drive to work every day and often encounter rush hours in the morning and evening. I’ve found that the parking lights are truly an invisible helper. They’re not as glaring as headlights, but they help outline my car’s silhouette during dusk, rainy nights, or dim underground garages. For example, when entering a poorly lit underground parking lot, the parking lights clearly show the width of my car, making it easier for others to avoid it. I’ve made it a habit to turn them on whenever the lighting is insufficient, and I’ve even shared this tip with friends: on rainy days on the highway, parking lights are more practical than hazard lights, as hazards are only for emergencies, while parking lights serve as a regular warning. Plus, when parked and waiting for someone, turning them on doesn’t bother the police—it actually reduces the risk of scratches. Remember to regularly wash your car and clean the light covers to maintain brightness and clarity. Small daily habits can bring great peace of mind.

[McAbigail]

I pay special attention to small car components. The position lamp, also known as the side marker light, is installed on both sides of the front and rear of the vehicle. Its purpose is to mark the edges of the vehicle. For example, when driving at night, it lights up to allow pedestrians and other vehicles to quickly gauge the overall size of the car, helping to prevent accidental collisions. I've learned to check these lights myself—common LED bulbs are more durable than old halogen ones, and if a bulb fails, the dashboard will alert you. By the way, avoid using high-pressure water on the light covers when washing the car, as water ingress could cause a short circuit. These lights are especially crucial in foggy conditions and work even better when paired with front fog lights, offering a simple yet effective way to enhance driving safety.