The DVS is a rating scale that aims to reduce the number of fatal collisions involving HGVs and vulnerable road users, where lack of vision is a contributing factor. It is designed to objectively measure a driver’s direct view through the windows of an HGV cab, and to define the level of risk to road users near the vehicle. This is expressed as a star rating from zero (poor) to five stars (good).
**Note: The above information from Transport For London