Two new synchronization strategies are developed for signalized grids of two-directional streets. Both strategies are found to reduce congestion significantly more than do other approaches. One of the strategies is static and the other adaptive. Both use a common timing pattern for all signals on the grid but use a different offset for each. The static strategy serves the morning rush by providing perfect forward progression on all streets in the directions that point toward a reference intersection, one that is located near the center of gravity of all workplaces. For the evening rush, perfect progression is achieved for all travel directions that point away from the reference intersection. The adaptive strategy toggles between this forward synchronization mode and a second mode suited for congestion, but only in a pre-determined district surrounding the reference intersection. Toggling is based on the district's real-time traffic density.

The paper shows how to switch quickly between the two synchronization modes without resorting to unacceptably short phases. It also shows that if the grid is formed by two intersecting sets of parallel streets, even if unevenly spaced, then every street can be perfectly synchronized in one of its directions. As a result, an inbound driver in the morning, or an outbound driver in the evening, is guaranteed to encounter synchronized signals over the full length of her trip. Although this is not possible for more irregular grids, the paper shows how to modify the two strategies for this case, so that they still perform well.

The strategies were benchmarked with simulations against a fixed, zero-offset strategy for many scenarios, because zero-offsets are known to work well under congestion. In one important scenario representing a severely congested morning rush, both strategies were also benchmarked against a state-of-the-practice computer program. While the state-of-the-practice program reduced the zero-offset delay by a modest 7%, the proposed strategies reduced it by 21% (static) and 32% (adaptive); i.e., improving on the state-of-the-practice program by 14% and 25%. These improvements considerably exceed the 1% to 5% reductions typically reported in the literature for other state-of-the-art methods that have been compared with state-of-the-practice programs. Similarly good results were obtained for the other scenarios, which included the morning and evening rushes, various distributions of workplaces, and both regular and irregular grids.

为双向街道的信号网格开发了两种新的同步策略。发现这两种策略都比其他方法更能显着减少拥塞。其中一种策略是静态的，另一种是自适应的。两者都对网格上的所有信号使用共同的时序模式，但对每个信号使用不同的偏移量。静态策略通过在所有街道上沿着指向参考交叉口的方向提供完美的前进服务，该交叉口位于所有工作场所的重心附近。对于晚高峰，所有远离参考交叉点的行进方向都实现了完美的进展。自适应策略在此前向同步模式和适合拥塞的第二种模式之间切换，但仅限于参考交叉路口周围的预定区域。切换基于该地区的实时交通密度。

该论文展示了如何在两种同步模式之间快速切换，而无需采用无法接受的短阶段。它还表明，如果网格由两组相交的平行街道组成，即使间隔不均匀，那么每条街道都可以在其一个方向上完美同步。因此，可以保证早上的入境司机或晚上的出境司机在整个行程中都能遇到同步信号。虽然这对于更不规则的网格是不可能的，但本文展示了如何针对这种情况修改这两种策略，以使它们仍然表现良好。

在许多情况下，这些策略都针对固定的零偏移策略进行了模拟基准测试，因为众所周知，零偏移在拥塞情况下可以很好地工作。在一个代表严重拥堵的早高峰的重要场景中，这两种策略也都以最先进的计算机程序为基准。虽然最新实践计划将零偏移延迟降低了 7%，但提议的策略将其降低了 21%（静态）和 32%（自适应）；即，将 state-of-the-practice 计划提高 14% 和 25%。这些改进大大超过了文献中通常报道的与最先进的程序相比的其他最先进方法的 1% 到 5% 的降低。在其他情况下也获得了类似的好结果，