Research Article

Freeway Traffic Speed Estimation of Mixed Traffic Using Data from Connected and Autonomous Vehicles with a Low Penetration Rate

Table 2

Car-following and lane-change parameters of RVs and CAVs in this study.

ParametersDefault value for RVsAdjusted value for CAVs

CC0, standstill distance (m)1.51.25
CC1, headway time (gap between vehicles) (s)0.90.5
CC2, car-following distance/following variation (m)43
CC3, threshold for entering following (s)−8−12
CC4, negative following threshold (m/s)−0.35−0.1
CC5, positive following threshold (m/s)0.350.1
CC6, speed dependency of oscillation (1/(m/s))11.440
CC7, oscillation during acceleration (m/s2)0.250.25
CC8, standstill acceleration (m/s2)3.53.5
CC9, acceleration at 50 miles per hour (m/s2)1.51.5
Look-ahead distance0 to 250 m0–500 m
Look-back distance0 to 150 m0–500 m
Observed vehicles210
Smooth close-up behaviourCheckedChecked
General behaviourFree lane selectionFree lane selection
Maximum deceleration, own vehicle (m/s2)−4−4
Maximum deceleration, trailing vehicle (m/s2)−3−3
−1 m/s2 per distance, own vehicle and trailing vehicle (m)100100
Accepted deceleration, own vehicle (m/s2)−1−1
Accepted deceleration, trailing vehicle (m/s2)−1−1
Waiting time before diffusion (s)60.0060.00
Minimum headway, front/rear (m)0.50.37
Safety distance reduction factor0.60.45
Maximum deceleration for cooperative braking (m/s2)−3−4
Cooperative lane changeNot checkedChecked
Maximum speed difference (km/h)33
Maximum collision time (s)1010
Collision time gain (s)22
Minimum longitudinal speed (km/h)11
Time before direction changes (s)00
Overtake same lane vehicle, minimum lateral distance standing (m) at 0 km/h10.75
Overtake same lane vehicle, minimum lateral distance driving (m) at 50 km/h10.75