In London and Greater London (but not the City of London), when the Metropolitan Police want the public’s help in their investigations of incidents and crimes, including traffic collisions, they erect “Witness Appeal Signs” near the scene.
“We are appealing for witnesses.” Singapore also uses these signs.
It seems in 2009, though, the Metropolitan Police banned the use of the signs except for traffic collisions. Some research indicated that the public perceived that, due to the presence of the signs, crime in the neighborhood was increasing. The Daily Mail article quoted one officer to say:
“They were placed where the crimes actually happened, so were very much targeted at people who might have seen something. Now that source of information has been cut off…”
The signs are placed and designed in such a way to be seen by people walking, biking, and driving near the scene of the incident.
How effective is this small sign posted on a pole compared to a bright Witness Appeal Sign in London?
I suggest that American police departments, Chicago’s included, look into installing similar signs for the most severe traffic collisions, starting with a bilingual “witness appeal sign” for the hit & run crash in Pilsen that killed Martha Gonzalez.