Travel Time Reliability Reference Manual/NPMRDS and INRIX Data Comparison
Comparison of INRIX and NPMRDS Data Sets
A comparison of speed data between INRIX and NPMRDS for January 2012 on a 4-lane inter-regional and 6-lane urban freeway.
|Urban 6-lane Freeway||INRIX||NPMRDS|
|Mean Speed (mph)||61.05||56.90|
|Standard Deviation (mph)||4.61||6.24|
|Median Speed (mph)||61.72||58.05|
|IR 4-lane Freeway||INRIX||NPMRDS|
|Mean Speed (mph)||65.32||63.42|
|Standard Deviation (mph)||3.69||4.83|
|Median Speed (mph)||65.49||64.00|
Particularly on the urban freeway, the NPMRDS data reports lower speeds than INRIX with higher variability. The matched pair graphs below reveal a similar trend represented by the linear fit with the intercept set to zero.