Yes they do ! If they use the same roads as 'regular' traffic - they must obey traffic signals etc.
A police office named William Potts of Detroit Michigan in 1920 invented the traffic signal. His race is not mentioned.
stop... A police officer assuming control of that intersection will have precedence over a traffic signal. If their signals are contrary to the traffic signal, you'll follow their signal.
Stop light is another name for a traffic signal.
traffic signal.
A signal light that is not working.
because its the same as a stop sigh in ontario anyway
we control traffic by follows the signal
positive
traffic signal, sign etc
4-way stop
4-way stop