Gas releases were detected at 6:30 am on 2 tanker railcars transporting concentrated nitric acid that were idle at a marshalling yard. The Internal Emergency Plan for hazardous substances was activated. A 50-m safety perimeter was set up and all rail traffic suspended. Toxicity measurements recorded adjacent to the railcars turned out to be negative.

A technical expert with the shipping company visited the site where the cars had been filled a few days prior. He observed that the leaks were located around degassing valves on the upper part of the cars. Their structural integrity was not in jeopardy. Given the lack of immediate danger, both rail and road traffic resumed at 10:30 am. The railcars were returned to their filling site around midday.

According to the operator, a breached seal on both cars’ valves, exacerbated by the extreme heat and extended exposure to the sun, had raised pressure in the cistern expansion space to a high enough level to cause leaking.