Under what circumstances may you use the shoulder of an interstate highway?

Using the shoulder of an interstate highway is permissible primarily for emergency situations. This means that if your vehicle breaks down, or if you are experiencing physical distress that requires you to stop, the shoulder serves as a safe area to pull over. The design of highway shoulders is intended to provide a safe haven for motorists in emergencies, ensuring that they are out of the main traffic lanes and minimizing the risk of accidents.

Options that involve non-emergency situations, such as checking a map or taking a phone call, are not valid uses of the shoulder because they can create hazards. Parking temporarily or long-term on the shoulder is also discouraged as it can obstruct traffic flow and increase the danger for all road users. The purpose of the shoulder is specifically to accommodate emergencies, keeping safety as the primary concern on interstate highways.