PROCESS

After importing these 2 data sets into Carto and processing the map a little bit, the figure above shows the traffic signals and crashes in Squirrel Hill. It's obvious that many of the locations of crashes overlap with the locations of the traffic signs. However, for the crashes are not at the same location with traffic signals, is there a correlation between the missing of the traffic lights and the crashes?  Here I introduced another color for the crashes happened at the intersections. There are 32 accidents in one year in this single neighborhood that were located at the intersections without traffic signals. If not taking consideration of the crashes on the highway. The number is 26 out of 121 crashes in total. One-fifth of the crashes are at the street intersections without the traffic light. So far, it looks persuasive that the city should add more traffic lights to prevent the crashes. However, another question comes to me. What about the number of the crashes at the intersections with traffic lights? It's 40! This definitely provides the counter-evidence to verify my assumption.