Identifying dangerous intersections using GIS


Every community, whether large or small, has the problem of traffic
accidents occurring on a daily basis. Most of these accidents take place
in and around road intersections. The Park Ridge Police Department is
constantly looking for ways to improve the safety at high risk
intersections and decrease the amount of accidents that take place
there. GIS was chosen as the best method to calculate the number of
accidents that occur at a particular intersection within a particular
time frame as well as illustrate how certain intersections had a
decrease in accidents after certain safety measures were instituted.

The GIS department has been mapping traffic accidents on a monthly,
bi-yearly and yearly basis going back many years in Park Ridge. A top
ten list of intersections with the highest amount of accidents is
calculated every six months from the accident maps and the higher counts
are studied further to see what changes could be made to improve the
safety at those locations. For the 2012 study, three locations were
chosen based off of high 2011 accident counts. Certain safety
improvements were made such as adding a “No Turn on Red” sign, adding an
additional stop side on the opposite side of a street, or simply just
changing the timing of the stoplights. After the 2012 accident totals
showed great improvement at those locations, a map was created
illustrating the sharp decline in accidents from 2011 to 2012 at those
highlighted intersections. Without GIS, the traffic coordinator would
spend an enormous amount of time browsing through accident reports,
counting the accidents by hand and then illustrating his or her findings
without the aid of a map