Unhealthy traffic conditions have significant adverse implications for environment-friendly, sustainable, and energy-efficient development. As an real-time environmental factor contributing to travel, comparing the effect mechanisms of weather on traffic conditions in multiple cities will provide a deeper understanding of the weather-traffic relationship. This study conducts a contrastive analysis of travel time index (TTI) variations under weather conditions in four cities. Notably, this study will consider the potential benefits of replacing an absolute index of traffic conditions, like traffic volume and travel speed, with TTI, a relative index. The results identified a strong association between complex weather measurements and traffic conditions. Overall, the impact of meteorological variables on TTI on non-weekdays might result in significantly worse traffic conditions. On weekdays, the impact is relatively weak, due to the flexibility for travel mode decision-making, especially during the commute hour. Weather impacts on traffic conditions are not only interrelated, like higher temperature with less rainfall or slower wind speeds, but they also varied with urban spatial layout and geographical condition. Besides, the traffic congestion is certainly related to extreme weather, but not closely. This study could benefit transit agencies by adding meteorological monitoring into traffic condition real-time analysis.

不健康的交通状况对环境友好、可持续和节能发展具有重大不利影响。作为影响出行的实时环境因素，比较天气对多个城市交通状况的影响机制，可以更深入地了解天气与交通的关系。本研究对四个城市在天气条件下的旅行时间指数 (TTI) 变化进行了对比分析。值得注意的是，本研究将考虑将交通状况的绝对指数（如交通量和行驶速度）替换为相对指数 TTI 的潜在好处。结果表明，复杂的天气测量与交通状况之间存在很强的关联。全面的，气象变量对非工作日的 TTI 的影响可能会导致交通状况明显恶化。在工作日，由于出行方式决策的灵活性，特别是在通勤时间，影响相对较弱。天气对交通状况的影响不仅相互关联，如气温较高、降雨较少或风速较慢，而且还因城市空间布局和地理条件而异。此外，交通拥堵固然与极端天气有关，但并非密切相关。这项研究可以通过将气象监测添加到交通状况实时分析中来使交通机构受益。天气对交通状况的影响不仅相互关联，如气温较高、降雨较少或风速较慢，而且还因城市空间布局和地理条件而异。此外，交通拥堵固然与极端天气有关，但并非密切相关。这项研究可以通过将气象监测添加到交通状况实时分析中来使交通机构受益。天气对交通状况的影响不仅相互关联，如气温较高、降雨较少或风速较慢，而且还因城市空间布局和地理条件而异。此外，交通拥堵固然与极端天气有关，但并非密切相关。这项研究可以通过将气象监测添加到交通状况实时分析中来使交通机构受益。