Final answer:
In case of an emergency that requires you to park on a highway, move your vehicle onto the shoulder, apply the parking brake, set up emergency signals, remain with your vehicle if possible, and lock it if you need to leave.
Step-by-step explanation:
When it is necessary to leave your vehicle parked on a highway or street due to an emergency, there are important safety rules to follow. First, you need to pull onto the shoulder of the road as far away from traffic as you can. If there's a curb, bring your vehicle close to it. After pulling over, you should set your parking brake, shift into park (or leave your vehicle in gear if it's a manual transmission), and then turn off the engine. It's vital to also set out the proper emergency signals to alert other drivers. If possible, stay with your vehicle until assistance arrives to ensure safety. However, if you must leave your vehicle, do remember to lock it to secure it.