Roadway Information and
Traffic Monitoring System Program
Travel speeds are measured continuously at various points along New Jersey highways at the weigh-in-motion (WIM) sites.
The WIM system detectors measure the speed of each vehicle that passes over the detection zone. This data is recorded and processed to
analyze the travel speeds and volumes. The daily average volume of vehicles for each 24-hour period is presented for each month in terms of
The information below is provided as Portable Document Format (PDF) files. You will need Adobe Acrobat Reader to view the PDF file, which
is available free from our state Adobe access page.
Average speed - the most commonly used speed statistic and is the sum of all individual speed
measurements divided by the total number of vehicles.
Median speed - the speed under which 50 percent of vehicles travel.
85th percentile speed - sometimes referred to as the critical speed as it is commonly used as a guide
in establishing reasonable speed limits. This represents the speed under which 85 percent of the vehicles are traveling.
NOTE: The last three columns of the table in the PDF files reflect the percentage of vehicles exceeding 65 miles per
hour, 70 mph and 75 mph.