Investigating the Affecting Factors of Speed Dispersion for Suburban Arterial Highways in Nanjing, China

Table 1

Summary of speed dispersion definitions in previous studies.

Author	Year	Method	Data
Solomon [18]	1964	Difference between individual vehicle speed and mean speed	Speed data along a segment
Garber & Gadiraju [16]	1989	Speed variance	Cross-sectional data
Aarts and Van Schagen [20]	1989	Difference between 85^th percentile speed and the average speed	Cross-sectional data
McFadden and Elefteriadou [22]	2000	The 85^th percentile maximum speed reduction	Cross-sectional data
Wang et al. [30]	2007	The standard deviation of the individual speed (SDIS); The average speed difference (ASD) of two neighbouring vehicles	Cross-sectional data
Guo et al. [11]	2011	The 85^th percentile individual speed difference; The 85^th percentile speed change rate	Cross-sectional data
Boonsiripant et al. [6]	2011	The variation of the 85^th percentile speed; Mean of 85^th percentile speed; Interquartile range of 85^th percentile speed; The difference between the 95^th percentile speed and the 5^th percentile speed (speed band); Mean of speed band; Variation of speed band	Cross-sectional data
Moreno and García [12]	2012	Ra-relative area measure of uniformity; Ea-relative area measure of speeding	Continuous speed data along a segment
Chung and Recker [28]	2014	The coefficient of variation of speed	Cross-sectional data
Wang et al. [31]	2016	Standard speed deviation (SD)	Cross-sectional data
Qiao et al. [32]	2017	The average of the speed deviation in the statistical time; The difference between the 85% speed and the 15% speed; The ratio of the SD to the average speed of the traffic flow	Continuous speed data in the statistical time
Gao et al. [43]	2019	The speed standard deviation, the coefficient of variation (CV)	Cross-sectional data