GIS assisting with speed surveys

​​​Blog_GISassistingwithspeedsurveys.jpg

It is simple to say that speeding occurs in almost any location that
there is a car and a road. Although this straightforward comment may be
true, it still leaves a lot of room for a Police Department or Traffic
Safety Engineer to question why. Is the speed limit too low? Are there
not enough stop signs on a specific street? Is the speeding occurring
near a high school? All of these questions are fair to ask and seem to
be brought up often when conducting a speed survey study. For the City
of Park Ridge they decided that on top of the typical questions that
they could ask they would also benefit from the use of a Geographic
Information System (GIS) analysis. The GIS would not only bring in a
mapping component to each speed survey study but it would also allow for
a city wide comparison as to how some of these studies may be spatially
related; both of which were not previously available.

In order to make the speed survey results usable within GIS the
information first had to be converted into a geographic data. This was
done by way of a complex GIS method called linear referencing and
entailed the representation of each speed survey study as a line on a
map. Furthermore, this complex operation worked by creating a new line
segment for each study area and did not require any splitting of the
original road centerline data. Most importantly, linear referencing
allowed multiple street segments (i.e. city blocks) to be consolidated
into one line segment holding the same attributes; something that was
very helpful considering that the city had many blocks that did not
start and stop at a street intersection and data editing would be
laborious. The end result came in the form of a map displaying each
study area with labels indicating the speed numbers that were recorded
during a specific month and year. In the end, although the GIS process
was a bit complex the goal was still achieved in the ability by taking
data that was once textual and making it an analytical tool via a map.

GIS assisting with speed surveys

​​​Blog_GISassistingwithspeedsurveys.jpg

It is simple to say that speeding occurs in almost any location that
there is a car and a road. Although this straightforward comment may be
true, it still leaves a lot of room for a Police Department or Traffic
Safety Engineer to question why. Is the speed limit too low? Are there
not enough stop signs on a specific street? Is the speeding occurring
near a high school? All of these questions are fair to ask and seem to
be brought up often when conducting a speed survey study. For the City
of Park Ridge they decided that on top of the typical questions that
they could ask they would also benefit from the use of a Geographic
Information System (GIS) analysis. The GIS would not only bring in a
mapping component to each speed survey study but it would also allow for
a city wide comparison as to how some of these studies may be spatially
related; both of which were not previously available.

In order to make the speed survey results usable within GIS the
information first had to be converted into a geographic data. This was
done by way of a complex GIS method called linear referencing and
entailed the representation of each speed survey study as a line on a
map. Furthermore, this complex operation worked by creating a new line
segment for each study area and did not require any splitting of the
original road centerline data. Most importantly, linear referencing
allowed multiple street segments (i.e. city blocks) to be consolidated
into one line segment holding the same attributes; something that was
very helpful considering that the city had many blocks that did not
start and stop at a street intersection and data editing would be
laborious. The end result came in the form of a map displaying each
study area with labels indicating the speed numbers that were recorded
during a specific month and year. In the end, although the GIS process
was a bit complex the goal was still achieved in the ability by taking
data that was once textual and making it an analytical tool via a map.