Motorists are required to move over or slow down when there is an emergency vehicle on the side of the road.
An emergency vehicle is any motor vehicle that is manufactured primarily to be used under conditions and circumstances of danger with respect to life and property. Also, they are generally marked with a red paint and fitted with a siren.
Typically, emergency vehicle are used by the fire departments, police, and hospitals such as an ambulance.
A broken-down vehicle refers to any vehicle that develops either a mechanical or an electrical fault on the road and as a result isn't able to continue in motion.
Generally, it's a standard requirement for the driver of an emergency vehicle to use a siren and put up a triangle sign a few meters from the emergency spot in order to alert other road users. Thus, this would help in ensuring that other drivers drive cautiously when they get to the emergency spot by either moving over to another driving lane or slowing down while moving past the vehicle.
In conclusion, when you sight an emergency vehicle as a driver, neither should you speed up to get passed the vehicle nor should you stop in the middle of the road.