Travel Time Reliability Reference Manual/NPMRDS and INRIX Data Comparison

Comparison of INRIX and NPMRDS Data SetsEdit

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.

   

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