There is a common misconception that driving at night is safer because there are fewer vehicles and pedestrians on the road. However, the recent death of Mr Balabhaskar, a prominent musician, following an after-hours road accident brought to wide attention the risks of night driving.
A substantial number of accidents occur at night, that is between the hours of 10 pm to 6 am. In fact, the absolute risk of having an accident is three times higher at night.
This article discusses the topic of night driving and provides practical solutions from the individual reader’s standpoint.
For this, a few principles of biology, physics and mathematics have to be kept in mind.
1. Biological Clock:
Just as every computer and mobile phone contains a built-in clock, there is a biological clock inside our brain, which has a 24-hour sleep-wake cycle. Natural sleep comes on at a fixed hour for most people, sometimes without warning. Sleep cannot always be willingly postponed.
2. The eye as a camera.
Our eyes work exactly like cameras. The dark portion on the front of the eyeball is called the iris. It can be brown, blue or green in colour. There is a small black opening at the centre of the iris, called the pupil. The pupil is similar to the aperture (opening) of a camera, with an ability to expand and contract to regulate the amount of light that enters inside the eye.
The retina is a light-sensitive membrane lining the back wall of the cavity of the eyeball, and can be compared to the film that is loaded inside a camera.
Just as a camera takes pictures when light enters through the aperture and falls on the film inside, we are able to see an object only when light from that object travels into the eye through the pupil and falls on our retina.
Any obstruction to the passage of light can result in a blurry image. Such an obstruction can either be located within the eye as in the case of cataract, or outside the eye as a result of rain, mist, dirty windshield or smudged spectacles.
For low-light photography, a larger aperture is chosen for the camera to capture all available light in order to produce images of dimly lit objects. Similarly, at night, our pupils enlarge, so that even the faintest light available will enter the eye to enable vision.
Abruptly shining a bright light into the eye at night can be quite disabling, as the pupils are already wide open.
This is the reason why high beam headlights are dangerous to oncoming drivers.
3. Tunnel vision
This refers to narrowing of the angle of vision with increasing speed. When our vehicle is stationary, our angle of vision is really wide. That is, in addition to the road, we can see objects far beyond the sides of the road—to a good distance. However, as the vehicle starts moving, our angle of vision narrows, limiting us to seeing only the road and those objects located close to the side of the road. As speed increases further, we are only able to see the centre of the road—we become blind to those objects located outside this narrow angle of vision. As a result, we fail to react when an unexpected movement occurs from the side of the road.
4. Braking distance:
This is the distance travelled by a vehicle to come to a complete stop after the driver applies the brake. As speed or vehicle size increases, braking distance also increases. A vehicle traveling at 30 kmph stops earlier than another similar vehicle that is doing 60 kmph; the braking distance for the latter will be double. This also means that the velocity at impact will be higher for the second vehicle, in the event of a collision.
5. Kinetic energy:
If a collision occurs, the extent of damage is mostly determined by the kinetic energy of the vehicle. Kinetic energy is calculated using the formula: ½MV squared (M=Mass, V=velocity). Accordingly, when the speed of a vehicle doubles, its kinetic energy increases four-fold.
6. Time management:
Faulty time management is the root cause of many road accidents. Out of the 1440 minutes available to us in a day, there are many who drive recklessly on the road to save just five or ten minutes of travel time. Such people habitually start their trip late, aiming to speed on the road and make up the time lost.
Unfortunately, by doing so, they are increasing the risk of accidents for themselves and other people.
Once we do the math, it can be seen that for a five-kilometre commute to work, traveling at a risky 60 kmph will only save a paltry five minutes when compared to driving at a safe 30 kmph.
Budgeting enough time for travel and starting early and important road safety principles.
Why night driving can be dangerous?
1. We could fall asleep while driving either from fatigue, or due to the natural sleep cycle as decided by our biological clock. Even if we are awake while driving, an accident could still occur if the driver of an oncoming vehicle fell asleep.
2. People tend to be less alert while driving at night because the roads are less crowded. The resulting sluggish emergency response can lead to accidents.
3. The casual attitude to safety at night also extends to the use of safety equipment. Failure to wear a seatbelt can turn fatal in a high-speed collision.
4. The chance of encountering a drunk driver is greater at night. Drunk drivers have sluggish reaction times, and are more likely to cause accidents.
5. Some people choose to drive faster at night because there are fewer vehicles on the road. However, it is difficult to control a vehicle at higher speeds, especially along a curve where there is limited visibility at night. Besides, braking distance gets prolonged.
6. The effect of tunnel vision is worse at night. The greater our speed, the worse our tunnel vision is.
7. Human beings are diurnal creatures, which means that they do not have natural night vision as in the case of cats and dogs. Headlights are not a substitute for natural night vision.
8. High beam headlights from oncoming vehicles can temporarily blind us while driving at night. At night, our pupils are wide open, causing our eyes to become extraordinarily sensitive to bright light.
In an attempt to compensate for the bright light, the pupils suddenly contract. As a result, we become temporarily unable to see other dimly lit objects on the road, such as pedestrians or other vehicles.
9. Not all vehicles have functioning headlights or tail lamps. In addition, it is common to see two-wheelers and other vehicles travel at night without lights switched on. Such vehicles can be invisible to other road users, leading to accidents.
10. A pedestrian walking along the road wearing dark clothes will not be readily seen by a driver who is seated inside the vehicle. This is because dark clothes absorb light and fail to reflect it. This problem with visibility gets worse when it rains.
11. While attempting to cross the road at night, pedestrians will not be able to judge the speed of an oncoming vehicle by looking at the vehicle’s lights alone. Bright lights can cause error of depth perception, especially for older people. However, during daytime, since they are able to see the actual vehicle, they can judge speed better and cross the road safely.
12. Those driving on unfamiliar roads might get surprised by potholes, unscientifically constructed medians, unauthorised barriers, illegal gaps on dividers or sharp curves on the road.
13. Speed-breakers (bumps) on the road are difficult to see at night. Variable in size and shape, they are not always signposted or marked clearly using white or yellow stripes. Two-wheelers can lose control while going over bumps at high speed.
14. Older people could have impaired night vision due to cataracts distorting the incoming light, causing halos and glare.
15. A few road users tend to break traffic rules under the cover of the night. They reckon that since no one is watching, they will not be penalised. Some people take advantage of the empty road to travel in the wrong direction on a one-way street. This can surprise a vehicle coming in the right direction, and result in serious head-on collisions.
16. Driving in the rain at night increases the risk of accidents. The road becomes slippery, prolonging the braking distance. The water droplets on our windshield scatter light, impairing our visibility further. Worn out wiper blades make it even worse.
What are the solutions?
1. It is safer to travel during the times when we are normally awake: that is according to our biological clock. If the trip can be avoided, it is better not to drive during unearthly hours.
2. If the trip is important and we need to drive, then we must ensure that we get adequate rest before the trip. We must not attempt a long night drive when we are tired after a hard day’s work; it is better to ask another person to drive.
3. If we feel sleepy while driving, we should immediately pull over at a safe place and take a short nap, keeping the parking lights on for visibility to other drivers. Sleep can come on rapidly while driving, and there is no room for error in such situations. The only cure for being sleepy while driving is to take a short break and get some sleep. Sometimes even a ten-minute nap can refresh the mind. Commonly recommended practices such as stretching of legs, opening the car windows and singing aloud are of no proven benefit in such cases.
4. During long distance driving, it is important to stop at least every two hours and take a break.
5. When we are driving alone, it can be difficult for us to reliably detect our own drowsiness. Hence, at night, it is safer to drive with a companion who can keep us awake through casual conversation. However, it is important that the conversation is not of distracting nature. The companion could take turns with driving too.
6. While engaging a driver, we must make sure that he is adequately rested before the trip. Too often drivers work double shifts, that is to take on a new trip immediately after a long trip.
7. While traveling with children, we must ensure that they are securely placed in a child seat. Children are not to be kept in our lap or held in our arms while the vehicle is in motion. A collision can easily snatch the child from our grip, turning them into fast-moving projectiles resulting in death or severe injury. Children under 13 should not ride in the front seat because if the passenger-side airbag deploys, serious injury to the child can ensue.
9. The headlights must be kept clean and free of dirt before the trip. Dirt or mist on the headlamp unit will disperse light, not only reducing our vision but also blinding oncoming drivers.
10. Those who wear spectacles must clean their glasses before the trip. A speck of dust or fingerprint on the glass can disperse light and cause a glare. Glare-free lenses are worth the extra expense.
11. The windshield must be cleaned thoroughly to reduce the chance of light getting scattered by dirt on the surface of the glass. The inside of the windshield also needs attention, as greasy fingerprints that are invisible by day can show up at night, affecting vision.
12. The wiper blade must be replaced at regular intervals, so that it wipes clean without leaving a trail of grease and dirt on the windshield. With time, the rubber on the wiper blade accumulates grease from the road, and is not easy to clean—especially when worn out.
13. The windshield water tank must be refilled before long trips, so that we are able to clean the windshield while driving at night.
14. Dashboard lights and other devices such as GPS should be dimmed to the extent possible. Bright light from inside the car’s cabin will not only distract us but also make our pupils smaller, preventing us from seeing dimly lit objects on the road ahead. The darker our environment, the larger our pupils become, enabling us to see better in the dark.
15. We must make sure that our tail lamps, brake lights, parking lamps and headlights are in good working condition. In addition to illuminating the road for us, lights improve our own visibility in the dark. It is equally important for other people to see us, as it is for us to see them.
16. Light etiquette: Parking lamps must be turned on at dusk to ensure that we remain visible to other road users as ambient light fades. Headlamps must be turned on only when it is sufficiently dark, so that we don’t blind other drivers with our glare. Low beam should be our default mode. High beam can be used on long empty stretches of road. Our high beam can blind oncoming drivers as well as those whom we are following, as our light gets reflected from the vehicle’s mirrors into the driver’s eyes. Therefore, we must dim our headlights when an oncoming vehicle is approaching, and also when we are traveling behind another vehicle.
17. If the oncoming vehicle is using high beam at night, looking directly at the light can blind us as our pupil constricts. We can prevent ourselves from being blinded by temporarily looking away to the far lower corner of our windshield. Without losing sight of the road, this manoeuvre reduces the quantity of light entering our eye and prevents our pupil from constricting excessively. Thus, we are able to keep a watch on the road markings and also observe the oncoming vehicle through the corner of our eye until it passes.
18. Beware the ‘one-eyed’ vehicle at night. Some large vehicles might have only one functioning headlamp. From a distance, as they have only one light glowing and the body of the oncoming vehicle is invisible in the dark, they can seem like a two-wheeler approaching. They can take us by surprise especially if the headlamp nearer to our side is not lit.
19. There is a natural tendency to drive faster because of empty roads. However, it is safer to drive at slower speeds at night. Slow driving gives us a chance to see things better and compensates for the diminished light to some extent. Lower speed also translates to shorter emergency braking distance.
20. Budgeting enough time for travel will prevent the urge to speed on the road to reach on time.
21. The practice of bragging about one’s ability to drive above speed limits and reach in the shortest time is to be discouraged. Not only does this demonstrate one’s callousness towards the safety of other road users, it also tempts other drivers to copy these hazardous habits. Fast driving is acceptable in controlled systems such as an autobahn but unsafe in countries where erratic road behaviour is the norm.
22. Night-time accidents commonly occur around curves on the road and at intersections, due to the presence of large blind spots. One must be extremely careful while driving through such high-risk zones.
Inexperienced drivers doing long trips at night will find it easier to patiently follow a large public transport vehicle. This is a convenient method of getting an escort.
23. While trailing a vehicle at night, we must verify that the vehicle in front has functioning brake lights, so that we can respond promptly if it braked suddenly.
24. If it rains while driving at night, we must either drive slowly keeping a safe distance from the vehicle in front, or pull over till the heavy rain passes. It is important to periodically check our tyre tread and change any worn-out tyres before rainy season starts. This helps prevent hydroplaning—when the smooth surface of the rubber tyre skids on a thin non-compressible film of water.
25. It is useful to learn to detect animals in the dark by spotting their eye glare against our headlights. At night, the only visible part of a large animal crossing the road could be the eyes which shine like a pair of tiny LED bulbs. This occurs when light gets reflected from the tapetum lucidum, a reflective layer located behind the animal’s retina.
26. While walking along the road at night, it is safer to wear white or other suitably lighter colours that can reflect light and improve our visibility to other road users.
Further reading:
2. Everyday health article on general road safety
3. Lecture on prevention of road accidents
4. WHO study of Indian roads and road safety by NIMHANS Bangalore