Driving Risk Affected Areas and Distribution Function of Sharp Horizontal Curves of Expressway

Table 2

Drivers’ instantaneous changes of heart rate, occurrence position, and operating speed before entering SHCs.

Radius (m)	Average instantaneous changes of heart rate (%)	Travel time before entering SHCs (s)	Average operating speed (km/hr)	Distances to point of tangent to spiral (m)
200~600	28.83	3.17	96	74.05
600~1000	28.26	3.31	100	85.51
More than 1000	21.89	7.06	101	197.15