It is known that connected and autonomous vehicles are capable of maintaining shorter headway and distances when they form platoons of vehicles. Thus, such technologies can potentially increase the road capacities of traffic networks. Consequently, it is envisioned that their deployment will also increase the overall network mobility. In this paper, we examine the validity of this expected impact, assuming that drivers select their routes selfishly, in traffic networks with mixed vehicle autonomy, that is, traffic networks with both regular and autonomous vehicles. We consider a nonatomic routing game on a network with inelastic (fixed) demands for a set of network origin destination (O/D) pairs, and study how replacing a fraction of regular vehicles by autonomous vehicles will affect the mobility of the network. Using well-known U.S. Bureau of Public Roads traffic delay models, we show that the resulting Wardrop equilibrium is not necessarily unique for networks with mixed autonomy. Then, we state the conditions under which the total network delay at equilibrium is guaranteed to not increase as the fraction of autonomous vehicles increases. However, we show that when these conditions do not hold, counterintuitive behaviors may occur—the total network delay can grow as the fraction of autonomous cars increases. In particular, we prove that for networks with a single O/D pair, if the road degrees of capacity asymmetry (i.e., the ratio between the road capacity when all vehicles are regular and the road capacity when all vehicles are autonomous) are homogeneous, the total delay is: 1) unique and 2) a nonincreasing continuous function of the fraction of autonomous vehicles in the network. We show that for heterogeneous degrees of capacity asymmetry, the total delay is not unique, and it can further grow as the fraction of autonomous vehicles increases. We demonstrate that similar behaviors may be observed in networks with multiple O/D pairs. We further bound such performance degradations due to the introduction of autonomy in general homogeneous networks.

中文翻译：

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自动驾驶车辆的存在将如何影响交通网络的平衡状态？

众所周知，联网的自动驾驶汽车在形成车辆排时能够保持较短的行驶距离和距离。因此，这样的技术可以潜在地增加交通网络的道路通行能力。因此，可以预见的是，它们的部署还将增加整体网络的移动性。在本文中，我们假设驾驶员在混合自动驾驶的交通网络（即既有常规车辆又有自动驾驶汽车的交通网络）中自私地选择路线，我们研究了这种预期影响的有效性。我们考虑了对一组网络原始目的地（O / D）对具有非弹性（固定）需求的网络上的非原子路由游戏，并研究了用自动驾驶汽车代替一小部分常规车辆将如何影响网络的移动性。使用美国知名 公共道路局交通延误模型显示，最终的Wardrop平衡对于具有混合自治权的网络不一定是唯一的。然后，我们陈述条件，保证自动平衡时总网络延迟不会随着自动驾驶汽车比例的增加而增加。但是，我们证明，如果不满足这些条件，则可能会发生违反直觉的行为-随着自动驾驶汽车比例的增加，总网络延迟可能会增加。特别是，我们证明，对于具有单个O / D对的网络，如果容量不对称的道路程度（即，所有车辆均处于正常状态时的道路通行能力与所有车辆均处于自治状态时的道路通行能力之间的比率）是同质的，总延迟为：1）唯一； 2）网络中无人驾驶车辆所占比例的连续性不断提高。我们表明，对于容量不对称程度的异质性，总延迟不是唯一的，并且随着自动驾驶汽车比例的增加，总延迟可能会进一步增长。我们证明，在具有多个O / D对的网络中可能会观察到类似的行为。由于在一般的同类网络中引入了自治性，我们进一步限制了这种性能下降。