evidence: Dense fog engulfed large swathes of north India reeling under intense cold as visibility reduced significantly, disrupting rail services and causing a vehicle pile-up in Uttar Pradesh, on Wednesday. [...] At least 11 people were injured in the pile-up involving several vehicles on the Lucknow-Gorakhpur National Highway, even as a moderate fog cloaked Delhi, where 18 trains were running late by one and a half to five hours.