evidence: 20 vehicles collide with one another on Yamuna Expressway due to dense fog A massive pile-up of vehicles took place on the Yamuna Expressway in Uttar Pradesh on Wednesday, due to low visibility amid dense fog in Delhi-NCR. Dense fog in Delhi-NCR on Wednesday morning caused a massive vehicle pile-up on the Yamuna Expressway which stretches from Greater Noida to Agra. The pile-up included at least 20 vehicles.