For emergency vehicles to change the traffic lights by remote.
If you have ever approached a large intersection in a sizable city, but the traffic lights are all blinking red, this would be a System is out of control situation. All vehicles must stop at the intersection barrier lines (crosswalk), then proceed when it is safe. When the System is in control, the intersection's right-of-way is being controlled by the lights, and the vehicles are flowing through the intersection in one direction while the vehicles in the crossing direction are waiting their turn... the system controls the flow.
Emergency vehicles lights are used to get the attention of other vehicles and for them to move out of the way. This is because such vehicles are usually going to an emergency and need to get there as soon as possible, therefore they need a special signal for other vehicles to move out.
In Wisconsin, only authorized emergency vehicles are allowed to use orange lights. These vehicles include police cars, fire trucks, and ambulances. Unauthorized vehicles using orange lights may be subject to fines or penalties for impersonating emergency vehicles.
They are normally used by emergency vehicles. They are to attract attention of drivers who do not pay as much attention. It is hoped to allow emergency vehicles the ability to get through traffic better.
They are allowed to exceed the speed limit when Lights and siren are all on.
WigWag lights - usually used on emergency vehicles when one headlight goes on and the opposite one goes off (flashes)
Because they are on an emergency run. They may be going to save someone's life, or prevent a crime.
Emergency vehicles carry a transponder that transmits a radio signal to change the traffic lights to green for them.
Not just ambulances, but many other emergency and police vehicles have a warning siren and flashing lights too. The lights and siren is to warn other road users ahead that a vehicle is on an emergency call and needs to get to the emergency as quickly as possible.
Uncontrolled intersection
yes strobe lights are legal so long as they are not used with flashing red /blue lights . Only emergency state vehicles are authorized to use such lighting for emergency use only. Personal vehicles can use or obtain strobe lighting only and can not be used with any other colored flashing lights.