I was thinking about various strategies we can use to control the spacing of bus and even out their headway. Turns out this has been already studied as a discipline of civil engineering.
From Fu and Yang’s paper on Design and Implementation of Bus–Holding Control Strategies with Real-Time Information:
Bus operations in urban environments are often subject to significant variations because of a variety of complex factors such as dynamic and stochastic traffic congestion and passenger demand. These variations, if not offset by control actions, will cause bus bunching—a well-known phenomena contributing to increases in passenger wait time and uncertainty in bus arrival times (1). Controlling bus operations is a way to compensate and reduce the effect of such variations so that the planned headway and schedule can be maintained. Among many bus control strategies, holding control is one of the most effective and common strategies that can be used to regulate bus operations. By holding early-arriving buses, bus headways can be evened out and service reliability improved.
The paper was published in 2002. They believe real-time information system can improve the performance of their model. Of course today system wide real time information are available. It is time to implement these kind of control system to improve the bus performance.