India, Feb. 6 -- What began as a routine downhill run through the Khandala ghat section on Tuesday evening unfolded into one of the most technically complex hazardous-materials rescue operations mounted on the Mumbai-Pune Expressway-a 32-hour exercise in patience, improvisation and precision, where a single spark could have triggered devastation across kilometres.

At around 5 pm on February 3, evening peak-hour traffic was building along the ghat stretch near the Adoshi tunnel, a section notorious for sharp curves and steep gradients. Just over an hour later, at kilometre marker 42 on the Pune-Mumbai carriageway, a gas tanker travelling downhill lost control while negotiating the curve and overturned on its side.

The BPCL tanker was car...