SafarSaathi: A Real-Time Multilingual Public Transport Companion Delivered over WhatsApp

Commuters in Indian cities make millions of trips a day by bus, metro and suburban rail, yet live transit information mostly sits inside map apps that expect a smartphone, mobile data, English literacy and some comfort with maps. This paper presents SafarSaathi, a multilingual public-transport companion that runs entirely inside WhatsApp. A commuter sends a text message, a voice note or a location pin in Hindi, Marathi or English. A large language model (LLM) layer works out the language, the intent and the origin and destination. OpenTripPlanner then plans a multimodal route over open GTFS schedules merged with GTFS-Realtime updates, and the answer (the next arrival, a trip plan or a service alert) goes back in the commuter's own language. The LLM never computes routes or times itself. We first review fifteen core studies on transit data, routing, arrival prediction, LLMs and Indic-language interfaces, and derive six design requirements from them. We then describe the system in full: objectives and scope, feasibility, an Agile development plan, data and functional analysis with data flow diagrams, hardware and software requirements, the layered architecture, the processing algorithm, the chat interface and the database schema. SafarSaathi needs no app install, works on low bandwidth, and can be extended to any city that publishes a GTFS feed. We close with the evaluation protocol for the prototype and plans for future work.