Dark Rainy Roads and Pedestrian Collisions – Why It Happens!
The rainy winter months are the worst for pedestrian fatalities and serious injuries in urban areas, with dark nights, slippery roads, lower visibility and darkly-clothed pedestrians increasing the risk of a motor vehicle colliding with a pedestrian.
The British Columbia Coroners Service reviewed pedestrian deaths by months from years 2010 through 2016 and established that the months from September through January saw a significant increase in the average number of pedestrian deaths (Figure 1). This time of year coincides with reduced light.
Figure 1: British Columbia Average Pedestrian Fatalities by Month during 2010 through 2016
A 2017 Insurance Corporation of British Columbia survey revealed that 9 in 10 drivers surveyed worried about hitting a pedestrian at night in wet weather, and 8 in 10 pedestrians don’t feel safe in these conditions.
Toronto Police Services has a database of motor vehicle/pedestrian collision since where a pedestrian was killed or seriously injured (KSI). Figure 2 shows pedestrian KSI incidence in Toronto between 2007 thru 2017.
Figure 2: Killed or Seriously-Injured Pedestrian Collisions in Toronto 2007-2017 by Location (Toronto Police Services)
The Toronto pedestrian KSI data indicated the following:
- 5,000 Killed or Seriously Injured (KSI) pedestrian collisions (avg. 455/year) occurred between January 2017 and January 2018
- 1,081 KSI pedestrian collisions (21.6 % of all incidents) occurred on wet roads
- 734 KSI pedestrian collisions (14.7% of all incidents) occurred on wet roads while it was raining
- 561 KSI pedestrian collisions (11.2% of all incidents) occurred on wet roads while it was raining and dark outside
- Of all KSI pedestrian collisions that occurred in the dark on wet roads while raining, 81 (14.4%) of KSI pedestrian collisions occurred between 5am and 8am, 192 (34.2%) of KSI pedestrian collisions occurred between 4pm and 8pm, and 278 (49.6%) of KSI pedestrian collisions occurred between 8pm and 5am
- Historical weather data indicates that rain falls, on average, on 34% of the days each year
Factors Leading to the Pedestrian Fatalities on Dark Rainy Roads
Wet roads will reflect light
- A black asphalt road has a rough texture that normally scatters and absorbs a large percentage of incident light. A rain-covered road is inherently smoother, causing a large amount of the incident light, coming at a low angle from headlights, to be reflected and making it harder to see the road then when the road is dry.
Pedestrian Clothing – Typically Dark and Non-Reflective
- In addition to a driver’s reduced ability to detect objects and signs due to rain, pedestrians are harder to see at night as many wear dark and non-reflective clothing.
- For a driver at night in a vehicle with its conventional low-beam headlight, Table 1 shows the detection distances to detect a pedestrian coming from the near (right) side of the roadway.
|Clothing Type||Low-Beam Headlight Detection Distance [metres]|
Table 1: Typical Low-Beam Headlight detection distance vs. clothing colour for pedestrian on right side of roadway
- The safety reflector, a highly reflective strip that could be applied to clothing, was developed in Finland in the 1960s. Reflectors are believed to increase pedestrian visibility for a driver from 25 metres to 140 metres – at 50 km/h vehicle speed they could provide an additional 8.3 seconds of time for a driver to respond to a pedestrian hazard.
- In Finland, it is the law that walkers wear reflective items in the dark and every child going to school must wear three reflective items on their clothes and backpack. In Scandinavian countries, it is acceptable for people to wear reflective clothing. As a result, Scandinavia has the lowest incidence of pedestrian accidents in the western hemisphere.
- A similar program for school children in Great Britain reduced child pedestrian deaths by 51%.
Rain on a Windshield Obscures Vision
- On a windshield, raindrops do not result in a film of water but instead behave like small moving beads of water whose properties will depend on the type of shape of windshield glass, speed of the wipers, and the speed that the vehicle is travelling.
- Raindrops will disturb a driver’s visual performance by reducing the sharpness of vision, resulting in an increase to the brain’s workload.
- Reduced visibility and detection distance when raining is even greater under conditions of low light, lower speed of wipers, and smaller raindrops.
- The use of wipers in the rain reduces the distance at which a driver could detect a pedestrian by about 20%, and a reduction of 45-68% in heavy rain. Example: a driver travelling 60 km/h could normally detect a light gray-clothed pedestrian at 59 metres (3.54 seconds) away in clear conditions and in heavy rain, initial detection of that pedestrian could be reduced down to as close as only 19 metres (1.14 seconds) away. Since an average driver will require 1.9 seconds to perceive and respond to a nighttime pedestrian hazard directly ahead, it would be impossible under this scenario for a driver to respond in time.
Tinted Windshields Reduces Detection Distance
- The Canadian federal Motor Vehicle Safety Act regulates that factory tinting of a windshield has to allow a minimum of 70% of light to pass through the glass. While no province allows one to put aftermarket tinting on windshields, the fines vary from $100 to $600. Quebec and Manitoba require a minimum of 70% light transmission and in Manitoba it’s 50%. Ontario and Newfoundland subjectively require drivers to be able to see other vehicles and pedestrians.
- A 70% tint would equate to a 30% transmissivity. For all tints greater than 30%, the recognition distance decreased by one-third. As an example, a motorcyclist wearing a 75% tint sunglasses (transmissivity of 25%) would recognize a dark object or pedestrian 25% later.
Drivers Take Longer to Respond to Hazards When Texting
The epidemic of driver texting while driving has been well profiled in the media. The exact effect of this behaviour on driver performance hasn’t been widely discussed but it is worth noting.
- The U.S. National Safety Council estimates that 1 out of every 4 accidents in the U.S. is caused by texting and driving. In a 2018 survey of 1,400 U.S. drivers, 41% admitted to reading texts while in moving traffic, 11% admitted to have texted while in moving traffic, 8% admitted to watching YouTube/Netflix videos while behind the wheel, and 18% admitted to checking social media while behind the wheel.
- Perception-response time is defined as the time required for a driver to detect, identify, decide upon a response, and physically initiate a response (i.e. steering or braking) to a hazard.
- Perception-response time of a driver detecting a pedestrian hazard is affected by factors including the setting (intersection or mid-block), available lighting, whether the pedestrian was seen to be stationary beforehand, and the darkness of the pedestrian’s clothing.
- A study of 42 drivers in Texas indicated that while reading or texting, the time taken to perceive and respond to a hazard was doubled and drivers were 11+ times more likely to miss a flashing light while they were texting.
Reduce the Odds of Colliding with a Pedestrian at Nighttime in the Rain
As a driver, you cannot control the actions or the clothing worn by a pedestrian, but you can act to ensure you have the best chance of detecting a pedestrian through attention to your vehicle and minimizing distraction.
- Clean your blades with vinegar every so often to reduce buildup.
- Replace worn wiper blades that leave sections of your windshield unclean or smeared.
- Consider windshield-coating products that can increase the glass’ surface tension so water can easily bead and fall from the windshield, further improving visibility.
- Stay off your phone
- Focusing on one cellphone will alters your focal length that has to then be adjusted when you refocus on the road.
- Your contrast sensitivity is adjusted by looking at a bright screen, reducing your ability to detect low-contrast pedestrians on a darkened roadway.
- Your attention is diverted reducing the amount of time you are scanning for pedestrians, doubling your reaction time and decreases your chance of detecting a pedestrian.
- Reduce interior/dash lighting
- Your eyes will adjust their sensitivity to see low levels of contrast based on ambient light levels. Reducing levels of the vehicle interior and the dashboard can enhance your ability to see darkly-clothed pedestrians.
Dark and rainy mornings and nights increase the odds of a pedestrian collision. It’s the rain, your wipers, reflections off the road, your eye’s ability to detect contrast in low light, a pedestrian’s clothing, and distraction from cellphones that factor into these collisions. Drivers need to consider these factors in order to keep the road safe for pedestrians and reduce the chances of a collision.
Be a safe driver and be extra attentive on those rainy roads.
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