Pedestrian safety - Global Road Safety Partnership

Pedestrian safety: a road safety manual for decision-makers and practitioners
1.4 Risk factors for pedestrian traffic injury
The discussion in this section concentrates on key factors that influence the risk
of pedestrian traffic injury: speed, alcohol, lack of pedestrian facilities, inadequate
visibility of pedestrians and inadequate enforcement of traffic laws. These factors
align well with the focus areas of a Safe Systems approach (see section 1.1.2), and
correspond to the intervention measures described in Module 4.
1.4.1 Speed
Travelling speed and the risk of a pedestrian crash
The speed at which a car is travelling influences both crash risk and crash
consequences. The effect on crash risk comes mainly via the relationship between
speed and stopping distance. The higher the speed of a vehicle, the shorter the
time a driver has to stop and avoid a crash, including hitting a pedestrian (52)
(see Figure 1.5). Taking into account the time needed for the driver to react to an
emergency and apply the brakes, a car travelling at 50 km/h will typically require
36 metres to stop, while a car travelling at 40 km/h will stop in 27 metres.
1: Why is addressing pedestrian safety necessary?
Figure 1.5 Speed and stopping distance for emergency braking
50
40
Speed (km/h)
30
20
10
0
0 5 10 15 20 25 30 35 40
Distance (m)
Source: 52
Figure 1.5 is based on a physical representation of an average situation in which a
driver takes 1.5 seconds to realize there is a risk of a collision with a pedestrian and
apply the brakes. The car will then stop under braking with a deceleration of 0.7g
after an initial latency period of 0.2 seconds for the brakes to be fully applied. In
some situations the driver may react more quickly and the car stop more rapidly, but
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