Three car accidents occurred on a particularly icy stretch of a Kings Langley road yesterday and the Met Office has issued a severe weather warning for drivers.
Police were called to the A41 bypass at 7.26am after a car and bus crashed into each other.
The car turned onto its side and the driver, a woman in her 40s, had to be cut from the vehicle. An ambulance attended the scene but the woman was not injured.
While police were at the scene, two other cars came off the same road in unrelated incidents.
Hertfordshire Constabulary contacted the Highways Agency due to concerns about ice and they later gritted the road.
The Met Office has issued a warning of possible icy stretches on roads in south west Hertfordshire.
The warning is valid from 5pm today to 10am tomorrow.