Kittery ME Interstate
95 FHWA Type 11 Southbound
2001
The JOHO image above is an example of the use of American
Image Inc.'s innovative visualization technique. Using JOHO,
you can make displays from your large traffic information bases. You can quickly
discern patterns and exceptions to the patterns, even in the large data sets
produced with vehicle sensors.
This image shows the total number of southbound FHWA Type 11 (double trailer)
trucks passing the sensor on Interstate 95 in Kittery, Maine for every hour in
2001. The image contains 8,760 data points. This is far more information than
traditional graphics programs can display.
Image Layout
The image has twelve panels, each showing one month in 2001, starting in the
upper left and ending in the lower right. As labeled on December’s panel, the
24 cells in the top row of a panel represent the hours in the first day of the
month. The bottom row of cells represents the last day of the month. The time
through each day is measured horizontally along each row, from the hour
beginning at midnight on the left to the hour beginning at 11 PM on the right.
Noon is halfway across the panel.
Each colored cell indicates the total number of southbound Type 11 trucks
passing the sensor at that day during that hour. The legend at the right
indicates the relation between color and number of vehicles. The image indicates
counts of fewer than 4 trucks as the dark blue color at the bottom of the
legend. At about 12 vehicles the color changes from green to orange. The white
at the top of the legend indicates a count of 25 vehicles or higher.
Image Interpretation
The most obvious pattern for these large trucks is that most of the
southbound traffic is in the hours from 8 PM until midnight. It is also
immediately clear that there are very few Type 11 trucks on the weekends. Note
also that at this site there is very little variation with season.
The pattern is due to the fact that these heavy trucks are heading south on
nighttime runs with goods for the Boston metropolitan area.
Careful inspection of the end of October and the beginning of November shows
a one-hour shift later in the pattern. This
is because the sensor clock remained incorrectly set to daylight savings time.
More Traffic Information
This southbound Type 11 traffic pattern is quite different from the
northbound pattern. Detecting
such patterns and directional differences would take hours of analysis using the
sensor vendor’s reporting software and traditional graphics programs. JOHO
makes them visible immediately with no additional labor after automated image
generation.
Gaps in the image represent periods when the sensor was inoperative.
With JOHO’s automated image updates, such failures are immediately
apparent, and corrective measures can be started in a timely manner.
This site also contains overweight FHWA Type 10 images and
total
vehicle count images that show other examples of how the Maine DOT
is using JOHO to monitor their sensors and to understand traffic patterns
throughout the state.
