By Mr Matti Koivurova, traffic safety engineer and world’s leading expert on pedestrian reflectors,    from LIIKENNETURVA – Central Organization for Traffic Safety in Finland.

Pedestrian and bicycle traffic is particularly prone to accidents in the dark. More than half of pedestrian deaths and nearly 50 % of injuries take place each year in the hours of darkness or twilight. And every fifth death or injury amongst cyclists also happens in the dark or twilight.

The accident risk for urban pedestrians and cyclists is at least 2-3 times higher in the dark than daylight. Outside towns, the risk of death in particular is multiplied during night compared to daytime. Making oneself more visible e.g. by using reflectors can diminish these risks.

Driving conditions in the dark

Even at their best, car headlights create relatively little forward lighting. The range of dipped lights in particular is very short. Symmetrical dipped lights extend around fifty meters, while the limit of asymmetrical light reaches a little further.
If the glass surface of the headlamp is dirty or scratched, or if there is moisture inside the lamp or its mirror surface is damaged, the effective range becomes even shorter. Adjustment faults or voltage losses in electrical devices may also shorten range.

A pedestrian or cyclist seen from e.g. 50 meters presents a small visual image and for that reason alone is hard to spot. The time available to use ones senses is also very short.

Light clothing and reflectors improve visibility by increasing background contrast.

Road lighting improves visibility mainly by creating a silhouette. The best road lights also illuminate the person on the road, who is then more likely to be seen clearly when he or she can be picked out from the background.

Visibility on an unlit road

Visibility on an unlit road depends primarily on the degree of reflectivity of the person and background, the power and direction of the car lights, the weather conditions and the eyesight of the driver.

A driver using full beam will see a person on the road from 200-600 meters away, depending on the clothing, and will pick out a reflector from 700 meters. The full beam of an oncoming car 400-500 meters away cuts a person’s visibility to 75 meters in the driver’s own full-beam lights. With dipped headlights by meeting an oncoming, a pedestrian can be seen 40-50 meters away, while a reflector is visible from 100-200 meters. This Swedish research into pedestrian visibility in the dark was conducted in ideal circumstances, with the cars in good condition and equipped with proper headlights while the people had good eyesight (1).

A very scratched windscreen decreases visible distance by 15 per cent, while weaker vision at a factor of only 0.5 cuts visibility by 15-20 %; when combined, these two factors reduce the distance seen by 25 % or as much as 20 meters (2). Windscreen scratching can be diminished with safety grooves that prevent dirt sticking to windscreen wipers. Swedish research (3) has indicated that nine drivers out of ten consider the safety groove a good device and more than half rate it very good in improving visibility.

For pedestrians, the visibility problem is somewhat different. There may be what seems to be sufficient light so that they imagine the driver sees them easily. In reality, they merge into the dark background unless wearing something light or luminous to distinguish them from that background. It is also recommended that one walk on the left-hand side of the road in right-driving countries (or vice-versa), facing the traffic because faces are more visible than dark clothes. But a reflector is the best way to make oneself seen in the dark.

Visibility on a lit road

Proper road illumination creates a good, steady luminous intensity without dazzle that makes it quite easy to spot the pedestrian on the road. But not all road illumination is well done, and where it isn’t there is insufficient contrast between pedestrian and background. The pedestrian then needs to be wearing an item of reflective material.
Illumination may be sufficient in urban areas due to neon lights and shop fronts, especially in city centers. There can be great differences in degrees of illumination however, even at short distances. It may be particularly difficult to spot a person say crossing the street, making it a good idea always to wear a reflector. They do no harm even in well-lit areas!

The driver’s potential to see

The headlights of an oncoming car often make it more difficult to spot a pedestrian in the dark. Scratches and dirt on the windscreen increase dazzle. The ability to see sufficiently early is also affected by the distance to the car ahead. When driving in heavy-flow traffic, it's harder for the driver behind to spot a pedestrian, if driving close to the car ahead.

Ageing weakens the driver’s night vision, as the need for light grows and the effect of being dazzled increases. Headlights directed too high up blind the oncoming driver and decrease visibility by as much as 20 %. On the other hand, headlights directed too low diminish the driver's own field of vision.

Dirt on the lights decreases their effect. In some road conditions, lights can get dirty in a short distance. In a test, driving e.g. on salted snow decreased the effectiveness of car lights by 60 % over 200 meters, cutting visibility by 15-20 %.

In poor weather conditions, a driver will spot someone on the road from no closer than 15-20 meters. There’s usually no time even to start braking or give way to the pedestrian or cyclist if they are in the car's path.

The driver’s potential to give way or stop

A sufficiently wide verge on the road makes it easy for the driver to pass a pedestrian or cyclist. No verge makes it more likely that the pedestrian or cyclist will be in the car's path, which they always are anyway when crossing a road.

The primary and most common response of the driver on spotting an individual is to attempt to avoid a collision by steering to one side. In the dark, the driver should also slow down and prepare to brake.

Reaction time once a driver has seen an object to be passed is 1-2 seconds. For example, a car travelling at 80 km/h proceeds 22 meters in one second and 44 meters in two. The latter and more realistic distance of 44 meters is - even in good conditions - plenty far enough for a driver with dipped headlights probably not to have time to steer around someone not wearing a reflector.

When it’s impossible to move to one side e.g. due to oncoming traffic, braking may be
considered the primary way to prevent a collision. Drivers should also brake to slow when they spot someone crossing the road, because the person may suddenly change his or her direction while so doing.

Driving at 80 km/h, in addition to 44 meters' reaction distance, the driver should prepare for at least 35 meters braking distance in good conditions on dry asphalt.

Braking distance doubles on wet asphalt, and rises by as much as a factor of four on wet ice. Being able to slow down in time makes it easier to control the situation.

Using reflectors to avoid accidents

Reflector use has been recommended since 1960’s, when pedestrian victims were about 300 and bicyclist victims about 130 year by year in Finland. In the year 2002 there were 40 pedestrians and 53 bicyclists killed on Finnish roads. Every third pedestrian uses a safety reflector in towns and two thirds outside of towns.

Research into pedestrian deaths in 1986-90 indicated 83 victims of dark or twilight incidents, 20 % of whom would have survived if they had worn a reflector (4).

Of 63 pedestrian victims on dark road in 1998-2002 it might have survived about 57 % outside towns and 45 % in towns by using a safety reflector or reflective material (5).

According to Norwegian estimates, increasing the use of reflectors from 30 to 70 % would cut pedestrian accidents by almost 15 %. Reflector use would also significantly improve cyclist safety. Using a reflector the risk of being hit from behind decreases 85 % (6).

The reflector's effect on visibility

The minimum requirements for a proper reflector are that an individual moving on the road can be seen from at least 140 meters in good conditions, with cars passing each other with dipped headlights.

This reflector visibility requirement is usually adequate for the driver to give way to pedestrians and cyclists on the road. When driving in heavy-flow traffic, there must be at least 3 seconds' distance to the car ahead in order to see the reflector (7).

The best places to attach a reflector to clothing are near the ends of the sleeves, at the waist and close to the knee.

American research has indicated that reflectors attached to limbs are visible from significantly further away (60-80 %) than those attached to other parts of the body (8).

Regulations concerning reflector use

The Finnish Road Traffic Act prescribed from 1.4.1982 that a pedestrian moving around in the hours of darkness elsewhere than on a pavement or cycle track, generally needs to wear an appropriate reflector. From 1.1.2003 pedestrian have to wear reflector generally on dark roads.

Different types of reflectors and their positioning

A retro-reflector refracts back light directed at it. Reflectors fall into two classes where the system used is either prism or glass bead. "Personal reflectors" can be divided into those that fasten permanently or temporarily to clothing.

A permanent reflector is usually either glued or sewed on to clothing by then manufacturer. It is recommended that approved reflector material is at least the minimum size stated in the approval data, and is attached in such a way that the wearer can be seen from different directions.

Removable reflectors attach to clothes with an easy-to-use mechanism that helps improve the pedestrian's visibility from different directions.

Improving visibility in twilight and daylight

A person’s visibility on the road can be improved using fluorescent material that transmits radiation at a longer wavelength than that which it receives.

Fluorescent materials "shine" as a result of ultraviolet light from the sun, adding visibility in daytime even when it's cloudy, but not after sunset. The best-seen colours of fluorescent material are greenish yellow, yellowish green and yellow.

European norms for pedestrian reflectors and "high-visibility" clothing

In connection with the CEN (European Committee for Standardization) directive on personal protection, a proposal for a European pedestrian reflector standard (EN 13356) has been drawn up, corresponding mainly to current Nordic standards.

The standards have been made, based on the same ppe-directive, for a “high-visibility" clothing of professionals (EN 471) and pedestrians (EN 1150). For the pedestrian requirement is that the outfit has 0.14 – 0,40 m2 of fluorescent material and 0,06 – 0,10 m2 of reflective material.

Fluorescent material forms the main part of for example a vest or blouse, and reflective material needs to be placed evenly as a wide visible ribbon around the body. Obviously, the smallest areas of material are used in children's outfits and the largest in adult's clothes. For instance, in a child's blouse there must always be at least 2 m of 3 cm wide ribbon or 1,2 m of 5 cm wide ribbon. In the largest sizes, there must be at least 2 m of 5 cm wide reflector ribbon.

Summary and instructions

Driver actions to improve security in the dark

The car’s lights, windscreen-cleaning devices, brakes and tyres need to be in good condition.

Driving speed must be kept down in conditions of particularly poor visibility. Full-beam lights must be used as much as possible so that lights are not dipped until meeting the beam of another car, and the driver should then slow down. Where a road has no verge, the driver should avoid driving at the road’s edge because of the risk of running over a pedestrian.

It’s good to keep a distance of at least 4 seconds to the car ahead in heavy-flow traffic. In addition to giving way, the driver must be prepared to simultaneously brake without locking the wheels.

The driver should use light and audio signals to warn anyone on the road. Any driver using dipped lights should at times use a short blink of full beam to look further ahead.

Pedestrian actions to increase their own safety

Pedestrians shouldn't move around in the twilight or darkness without effective reflectors. Special alertness is required when crossing a road.

It is recommended that pedestrians use the left-hand side of the road in right-driving countries (and vice-versa).

Cyclist actions to increase their own safety 
 
The bicycle must be equipped with effective wide-angle front, rear and side reflectors. A reflector safety-flag gives the cyclist more space when a car is passing. Bicycle must be equipped with a front light. A rear light is strongly recommended. A car coming from behind is often not heard, but can be seen with a mirror.

The cyclist must drive on the right-hand edge of the road in right-driving countries.

Don't begin to cross a road before making sure you can do it safely.

The above information comes from Mr Matti Koivurova, traffic safety engineer – vehicles and safety equipments, at LIIKENNETURVA – Central Organization for Traffic Safety in Finland. Translation by Kim Pasanen. 

References:
1. Rumar K: Visibility distances with halogen and conventional headlights, Scandinavian journal of psychology, 1974, Sweden.
2. Lundkvist S-O, Helmers G: Reduction of visibility distance with low vision and/or worn out windshield, VTI 382 -Swedish National Road and Transport Research Institute, 1993.
3. Jingryd K: The effect of a safety slot on the windscreen for being worn out and dirty, VTI 19 -Swedish National Road and Transport Research Institute, 1995.
4. Karttunen R: Serious accidents to the light traffic, Valt  -The Faculty of Social Sciences 1991, Finland.
5. Holopainen A: Pedestrians and cyclists in fatal road accidents, Valt -The Faculty of Social Sciences 2004, Finland.
6. Elvik R: The impact and effect of pedestrian reflectors on the number of pedestrian accidents in the dark.
The Institute of Transport Economics –TØI 1996, Norway.
7. Summala H: Latencies in vehicle steering: experimental studies on drivers behaviour on the road, General psychology monographs B2/81, University of Helsinki 1981, Finland.
8. Luoma J, Schumann J, Traube E.C: Effects of retro reflector positioning on night time recognition of pedestrians, The University of Michigan Transportation Research Institute UMTRI-95-18, 1995 USA.