Page - (000626) - in Autonomes Fahren - Technische, rechtliche und gesellschaftliche Aspekte

60527.5 Raise the Playing Field Imagine a driver traveling down a typical neighborhood street with a parking lane that provides 3 m between her car and the curb, as shown in Figure 27.2. Assuming that her view of the pedestrian is not blocked, what maximum speed will enable this driver to stop for any pedestrian who, at a walking speed of 1.4 m/s, steps from the curb into the street? Although stopping sight distance depends on several vehicle, environment, and driver variables [1], this illustration simplifies these to consider only the driver’s reaction time and the friction between the tires and the road surface. An average driver with good tires on a flat dry street might achieve a reaction time of 1 s and a subsequent deceleration rate of 5 m/s2, which implies a maximum speed of 20 km/h (13 mph).4 In contrast, a hypotheti- cal automated vehicle reacting twice as fast and braking at 7 m/s2 could reach a maximum speed of about 40 km/h (25 mph),5 which is a typical residential speed limit today. In other words, if automated vehicles are traveling slowly on a road, perhaps conventional vehicles should be traveling even more slowly. Reasonable speed is also an answer to some, though not all, of the ethical dilemmas popularly raised in the context of automated driving [10], [32]. Positing a choice between killing one group of pedestrians and another, for example, fails to account for the possibil- ity of negating the dilemma simply by driving more slowly. Slower speeds can increase controllability as well as reduce the magnitude of harm. Speed is not the only relevant driver action. Tire condition, for example, is an important consideration in stopping distance, is at least nominally regulated [2], and yet varies widely within the current vehicle fleet. If the hardware on automated vehicles is expected to be regularly inspected, so too should the hardware on conventional vehicles. Moreover, 4 initial speed = rate of deceleration * ((pedestrian speed / orthogonal distance from curb to car) – reaction time) = (0.5 * 9.8 m/s2)*(((1.4 m/s)/3 m) – 1 s) = 6 m/s = 20 km/h = 13 mph. 5 initial speed = rate of deceleration * ((pedestrian speed / orthogonal distance from curb to car) – reaction time) = (0.7 * 9.8 m/s2)*(((1.4 m/s)/3 m) – 0.5 s) = 11 m/s = 41 km/h = 25 mph. Figure 27.2 Illustration of Vehicle Stopping