TWO accidents, one involving four casualties and the air ambulance, caused heavy delays on the westbound A14 this afternoon. The first happened just after midday when a lorry turned onto its side at junction 21 (Brampton). No one was reported hurt. Shortly before 3pm, however, four people were injured when a van overturned at the Alconbury exit. Two other vehicles were involved in the incident, one of them a Ford Mondeo, police said. The air ambulance was called out to treat the injured van driver.