eclipse-sumo/sumo ? reverse-engineered prompt

Build me an open source traffic simulation app that can model city roads, cars, buses, bikes, and pedestrians in the same scenario. I want it to handle big road networks, let me create or load a map, set routes and travel demand, and then watch the traffic move through the network in a realistic way.

Please include the main pieces a user would expect, like tools for setting up scenarios, running simulations, and viewing results, plus clear docs and example setups so someone can get started without already being an expert. It should run on the major operating systems and be built in a way that makes it practical for researchers or planners to use on large projects.

If you need to look up current docs online while implementing it, do that. I care most about having a solid, working traffic simulation package with good examples and a clean way to extend it later.