What does this sign mean?

• Drivers must follow the alternate route marked as "D-1" to bypass a closed or restricted area.
  Explanation:

  "This road sign informs drivers that they need to follow the detour markers provided until they can return to their regular route. It guides drivers through an alternative route when the main road, such as a provincial highway, is closed due to construction, maintenance, or other reasons."
• Only truck drivers must follow these detour markers until they reach their regular route in case of a closed provincial highway.
• Drivers must follow these detour markers to exit the highway safely.
• This sign guides drivers to the nearest fuel pump.