The Omnibus Java library efficiently derives optimal signal schedules for multimodal intersections. Specifically, intersections among tram lines with right of way and vehicle flows are considered, minimizing the maximum expected percentage of queued vehicles of each flow. Trams are modeled by Stochastic Time Petri Nets (STPNs), capturing periodic tram departures and bounded delays and travel times with general (i.e., non-Exponential) distribution. Vehicles are modeled by finite-capacity vacation queues with general vacation times determined by the intersection availability. For each vehicle flow, the expected queue size over time is derived, as well as the steady-state distribution of the expected queue size at multiples of the hyperperiod (resulting from nominal tram arrival times and vehicle traffic signals). Then, the behavior of each vehicle flow can be studied over intervals of arbitrary duration by just performing transient analysis for the hyperperiod duration, starting from the steady-state distribution of the expected queue size. Omnibus is notably designed to facilitate code usability, maintainability, and extensibility. It is available open source under the AGPLv3 licence. In particular, Omnibus leverages the SIRIO Library of the ORIS tool to model duration distributions and to specify and analyze STPNs.