This paper examines strategies that share road space capacity in a flexible manner at a given element of the arterial (e.g. intersections) to move buses in front of the car queues without continuously banning cars from using one full lane. We build a generalized analytical framework with fixed set theory to evaluate bi-modal arterials with any kind of flexible sharing strategies. These strategies are modelled parsimoniously using a single parameter to describe their effectiveness. This parameter can be estimated analytically, empirically, or with simulations. Overall, the mathematical formulation is versatile, as it applies to both intuitive cases when the arterial capacity is shared in a fixed manner, and non-intuitive cases when flexible sharing strategies are installed. This framework can provide practitioners both analytical and graphical tools to systematically and quantitatively evaluate any given bi-modal arterial. Moreover, the requirements to efficiently install flexible sharing strategies along the arterial are established. Lastly, one particular flexible sharing strategy, the pre-signal, is illustrated as an example both mathematically and with a calibrated simulation.
All Science Journal Classification (ASJC) codes