Attachm C <br />Pedestrian safety: a road safety manual for decision-makers and practitioners <br />Attach t B <br />1.4 Risk factors for pedestrian traffic injury <br />The discussion in this section concentrates on key factors that influence the risk <br />of pedestrian traffic injury: speed, alcohol, lack of pedestrian facilities, inadequate <br />visibility of pedestrians and inadequate enforcement of traffic laws. These factors <br />align well with the focus areas of a Safe Systems approach (see section 1.1.2), and <br />correspond to the intervention measures described in Module 4. <br />1.4.1 Speed <br />Travelling speed and the risk of a pedestrian crash <br />The speed at which a car is travelling influences both crash risk and crash <br />consequences. The effect on crash risk comes mainly via the relationship between <br />speed and stopping distance. The higher the speed of a vehicle, the shorter the <br />time a driver has to stop and avoid a crash, including hitting a pedestrian (S2) <br />(see Figure 1.5). Taking into account the time needed for the driver to react to an <br />emergency and apply the brakes, a car travelling at 5o km/h will typically require <br />36 metres to stop, while a car travelling at 4o km/h will stop in 27 metres. <br />Speed and stopping distance for emergency braking <br />50 <br />40 <br />E 30 <br />20 <br />a <br />U) <br />10 <br />5 10 15 20 25 30 35 40 <br />Distance (m) <br />Source: 52 <br />Figure 1.5 is based on a physical representation of an average situation in which a <br />driver takes 1.5 seconds to realize there is a risk of a collision with a pedestrian and <br />apply the brakes. The car will then stop under braking with a deceleration of 0.79 <br />after an initial latency period of o.z seconds for the brakes to be fully applied. In <br />some situations the driver may react more quickly and the car stop more rapidly, but <br />