Final answer:
Emergency vehicles are typically the only ones permitted to use the shoulder of a highway, although local laws may allow buses or cyclists under specific conditions. Rules can vary by region and local traffic laws should be consulted.
Step-by-step explanation:
The shoulder of a highway is typically reserved for emergencies and certain special cases of necessity. Regularly, the only vehicles that are permitted to use the shoulder are emergency vehicles such as ambulances, fire trucks, and police cars when they are responding to emergencies. In some jurisdictions, other vehicles such as public transportation buses or bicycles might be allowed to use the shoulder under specific conditions or during designated times. However, these rules can vary by region and local laws should always be consulted. Cyclists, for example, depending on the area, might be allowed on the shoulder if there is no separate bike lane available. Motorcycles, in general, are not allowed to ride on the shoulder and must adhere to the same traffic rules as other motor vehicles. It's crucial to follow the specific traffic regulations of your area to ensure road safety for all users.