Who has the authority to issue commands that drivers must obey at crossings?

The authority to issue commands that drivers must obey at crossings is held by police officers and school crossing guards. This is based on their roles in maintaining public safety and managing traffic flow. Police officers are trained law enforcement personnel who ensure adherence to traffic laws, can direct vehicles at intersections, and have the authority to enforce compliance for the safety of all road users.

School crossing guards, typically stationed near schools, play a crucial role in protecting children as they cross streets. They are authorized to instruct vehicles to stop when children are present, ensuring a safe environment for students.

In contrast, local citizens do not have the authority to direct traffic or issue commands. Drivers on the road are required to follow the commands of authorized personnel but do not possess command authority themselves. Traffic signs provide guidance and regulation but do not issue commands in an active sense like law enforcement or crossing guards. Therefore, the correct answer reflects the essential roles that these trained individuals play in ensuring safe crossings and adherence to traffic laws.