Three sequential experimental scenarios encountered during continuous formation motion simulation:
1) Scenario A: A small obstacle is present in the uppermost lane of the formation.
2) Scenario B: An obstacle vehicle is present in the lowermost lane of the formation.
3) Scenario C: The formation passes the obstacle vehicle.
Formation control of Connected and Autonomous Vehicles (CAVs) has shown significant potential for improving traffic safety and efficiency in multi-lane traffic. However, previous work has primarily focused on spatial coordination without temporal considerations, which significantly limits their practical applicability in real-world traffic. In this paper, we propose a Spatio-Temporal Formation Control method (STFC) that integrates centralized formation generation with distributed trajectory planning. Precisely, we propose a graph-based formation maintenance representation, and show that the interlaced geometric structure is optimal for multi-lane formation. Then, we develop a distributed spatio-temporal joint formation trajectory planning method that simultaneously optimizes spatial positions and temporal duration, with consideration of multiple objectives such as formation maintenance and obstacle avoidance. Further, we design a polynomial vehicle-to-target assignment algorithm that inherently resolves conflicts. Simulation experiments demonstrate the superiority of our approach over baseline methods in terms of formation maintenance and transition.