  Guaranteeing the quality of transit service is of great importance to promote
the attractiveness of buses and alleviate urban traffic issues such as
congestion and pollution. Emerging technologies of automated driving and V2X
communication have the potential to enable the accurate control of vehicles and
the efficient organization of traffic to enhance both the schedule adherence of
buses and the overall network mobility. This study proposes an innovative
network-level control scheme for heterogeneous automated traffic composed of
buses and private cars under a full connected and automated environment.
Inheriting the idea of network-level rhythmic control proposed by Lin et al.
(2020), an augmented rhythmic control scheme for heterogeneous traffic, i.e.,
RC-H, is established to organize the mixed traffic in a rhythmic manner.
Realized virtual platoons are designed for accommodating vehicles to pass
through the network, including dedicated virtual platoons for buses to provide
exclusive right-of-ways (ROWs) on their trips and regular virtual platoons for
private cars along with an optimal assignment plan to minimize the total travel
cost. A mixed-integer linear program (MILP) is formulated to optimize the RC-H
scheme and a bilevel heuristic solution method is designed to relieve the
computational burden of MILP. Numerical examples and simulation experiments are
conducted to evaluate the performance of the RC-H scheme under different
scenarios. The results show that the bus operation can be guaranteed and the
travel delay can be minimized under various demand levels with transit
priority. Moreover, compared with traffic signal control strategies, the RC-H
scheme has significant advantages in handling massive traffic demand, in terms
of both vehicle delay and network throughput.
