July to September
Explanation
The operational status of high-altitude mountain highways in the Himalayas is strictly governed by climatic conditions, specifically heavy snowfall and the accessibility of mountain passes. The Manali-Leh Highway traverses several high passes, including Rohtang La, Baralacha La, Lachulung La, and Tanglang La, which remain snowbound for a significant portion of the year.
Analysis of Options:
- Throughout the year Throughout the year: Incorrect. The highway is not an all-weather road. Extreme winter conditions and heavy snow accumulation on passes like Baralacha La and Tanglang La make it impassable during winter and early spring.
- November to February November to February: Incorrect. These months constitute the peak winter season in the region. The highway is officially closed to all vehicular traffic due to sub-zero temperatures and massive snow blockades.
- July to September July to September: Correct. The Border Roads Organisation (BRO) typically completes snow-clearing operations by late May or June. The highway is fully operational and safest for civilian traffic from July to September, before the onset of winter snowfall in October.
- March to May March to May: Incorrect. During March and April, the passes are still covered in deep snow. While snow-clearing operations may commence in spring, the road is generally not open to civilian traffic until late May or early June.
Key Takeaway:
The Manali-Leh Highway is a seasonal route, typically open for vehicular traffic only during the summer and monsoon months (June to October), with the most reliable window being July to September.