AI 中文总结
研究无信号双向街道通过设置单车道瓶颈疏导交通，对比先进先出和方向优先级两种策略，考量预期延迟和系统容量等指标，分析单瓶颈及多瓶颈街道情况，得出不同策略下的性能表现及容量相关结论。
AI 中文摘要
在无信号的双向街道上疏导交通的常用策略是在一个或多个位置将街道缩窄为单车道，这些位置成为瓶颈。常用两种策略：先进先出（FIFO）和方向优先级（DP）。本文研究这两种策略在有一个或多个瓶颈的街道上的性能。考虑两个性能指标：预期延迟（针对低需求典型情况评估）和系统容量。对于单瓶颈街道，FIFO和DP下的容量都不唯一。低需求时FIFO预期延迟低于DP，高需求且流量平衡时DP容量超过FIFO。对于多瓶颈街道，低需求时总延迟是单瓶颈延迟乘以瓶颈数量，FIFO下多瓶颈街道容量与单瓶颈相同，DP下接近容量时交通复杂且容量点众多不连续，给出了计算公式，较长街道通常有更高容量，且这些容量点常高于单FIFO或DP瓶颈街道的容量边界。
英文摘要
A common strategy to calm traffic in an unsignalized, bidirectional street consists in narrowing the street to a single lane at one or more locations. These locations become bottlenecks. Two policies are commonly used there: first-in-first-out (FIFO), and directional priority (DP), which means one of the directions has priority. This paper examines the performance of these two policies on streets with one or more bottlenecks. Two measures of performance are considered: the expected delay (evaluated for typical situations with low demand) and the system capacity. The latter is defined as the pair of flows (d1, d2) that depart the street in the two opposite directions when the system is oversaturated with queues. For a street with a single bottleneck, the capacity under both FIFO and DP is not unique: In both cases, the values of (d1, d2) form a continuous decreasing curve. As expected, we find that arrival flow pairs (a1, a2) below this curve can get through the system without generating queues. Those above cannot. For a single bottleneck it is shown that FIFO yields lower expected delay than DP under low demand. For high demand, DP's capacity exceeds FIFO's when the flows are balanced, but are lower otherwise. For multiple bottlenecks, the expected total delay on the street under low demand is that of a single bottleneck multiplied by the number of bottlenecks. The multi-bottleneck capacity under FIFO turns out to be the same as for a single bottleneck. For DP, traffic near capacity is complex. Capacity points turn out to be numerous and disjointed. Formulas are derived for their values. Higher capacities are typically obtained for longer streets. Curiously, these capacity points are often above the capacity curve of a street with a single FIFO or DP bottleneck, indicating that an extra bottleneck can increase capacity.
