  This paper reports an experimental study on oscillation growth in mixed
traffic flow of automated vehicles (AVs) and human driven vehicles (HVs). The
leading vehicle moves with constant speed in the experiment. The following
vehicles consist of six developable AVs and different number of HVs. Thus, the
market penetration rate (MPR) of AVs decreases with the increase of platoon
size. The AVs are homogeneously distributed in the platoon. The constant time
gap car-following policy is adopted for the AVs and the gap is set to 1.5 s.
The experiment shows that in the 7-vehicle-platoon, the oscillations grow only
slightly. In the 10-vehicle-platoon, the AVs could still significantly suppress
the growth of oscillations. With the further decrease of MPR of AVs in the 13-
and 20-vehicle-platoon, the AVs become having no significant impact on
oscillation growth. On the other hand, with the decrease of MPR of AVs, average
density of the vehicles and flow rate of the platoon increase, which
demonstrates a trade-off between traffic stability and throughput under the
given setup of AVs. The simulation study is also carried out, which exhibits
good agreement with the experiment. Finally, sensitivity analysis of the
parameters in the AV upper-level control algorithm has been performed, which is
expected to guide future experiment design.
