Page - (000428) - in Autonomes Fahren - Technische, rechtliche und gesellschaftliche Aspekte

413 Fig. 19.6 Congestion effects in AMoD systems [13]. Top left: Layout of the 9-station road net- work. Each road segment has a capacity of 40 vehicles in each direction. Bottom left: The first pic- ture shows the 9-station road network without rebalancing. The color on each road segment indi- cates the level of congestion, where green is no congestion, and red is heavy congestion. The second picture is the same road network with rebalancing vehicles. Right: The effects of rebalancing on congestion. The x-axis is the ratio of rebalancing vehicles to passenger vehicles on the road. The y-axis is the fractional increase in road utilization due to rebalancing. 19.4 Future research directions linear program discussed in Section 19.2.2.1. The x-axis shows the ratio of rebalancing vehicles to passenger vehicles on the road, which represents the inherent imbalance in the system. The red data points represent the increase in average road utilization due to rebal- ancing and the blue data points represent the utilization increase in the most congested road segment due to rebalancing. It is no surprise that the average road utilization rate is a linear function of the number of rebalancing vehicles. However, remarkably, the maximum con- gestion increases are much lower than the average, and are in most cases zero. This means that while rebalancing generally increases the number of vehicles on the road, rebalancing vehicles mostly travel along less congested routes and rarely increase the maximum con- gestion in the system. This can be seen in Figure 19.6 bottom left, where rebalancing clearly increases the number of vehicles on many roads but not on the most congested road segment (from station 6 to station 5). The simple setup in Figure 19.6 suggests that AMoD systems would, in general, not lead to an increase in congestion. A particularly interesting and intriguing research direction is to devise routing algorithms for AMoD systems that indeed lead to a decrease in congestion with current demand levels (or even higher). A promising strategy relies on the idea that if AMoD systems are implemented such that passengers are given precise pickup times and trips are staggered to avoid too many trips at the same time, congestion may be reduced. Passengers may still spend the same amount of time between requesting a vehicle and