Evaluation of Roundabout Safety Performance through Surrogate Safety Measures from Microsimulation
Table 4
Default and calibrated values of the model parameters in AIMSUN.
Model Parameter
Roundabout
Single-Lane
Double-Lane (Right Lane)
Double-Lane (Left Lane)
Turbo
reaction time [s]
default
0.80 (0.10, 1.50)
0.80 (0.10, 1.50)
0.80 (0.10, 1.50)
0.80 (0.10, 1.50)
calibrated
0.86 (0.82, 0.86)
0.94 (0.85, 0.95)
0.95 (0.85,0.95)
1.00 (0.10, 1.50)
min headway [s]
default
0.00
0.00
0.00
0.00
calibrated
1.58 (1.50, 1.70)
1.00 (1.00, 1.50)
1.33 (1.00,1.50)
1.70 (1.00, 1.70)
speed acceptance
default
1.10
1.10
1.10
-
calibrated
1.00 (1.00, 1.10)
0.95 (0.90, 1.10)
0.97 (0.90,1.10)
-
GEH index [%]
def.
56.25
78.10
78.10
85.00
calibr.
87.50
96.90
93.80
99.00
Note: the acceptance range for AIMSUN model parameters is the upper and lower bounds used for GA calibration [23, 24]; the same values of the model parameters were used for each entry lane [25]; the model parameter ranges from a minimum of 0.90 to a maximum of 1.30 as AIMSUN proposes; the same GEH indexes were obtained for each entry lane.
