Initially, authorities thought the smoke that caused the closure of the Grouft tunnel was actually dust that had accumulated after being unused for so long. But on Thursday morning, the National Roads Administration explained the tunnel had been thoroughly cleaned, putting that hypothesis to bed.
The road had been cleaned three times before it was reopened to traffic, the Administration clarified.
In actual fact, the "smoke" turned out to be dust clouds emanating from a construction site nearby. "A building site near the tunnel created immense amounts of dust, which was carried over the road by the wind, and into the tunnel."
As the dust was so fine, it remained in the air a long time, forming visible clouds.
The National Roads Administration said it had spoken to the company managing the building site and that they had agreed to take the "necessary measures" to avoid creating dust clouds in future, such as regular cleaning.
