System designHardsd-g138

Subject Eta predictionLevel Senior–Staff~50 minCommon in ML systems · Distributed systems · Algorithms & data structures interviewsIndustries Technology

Question

Design the ETA / travel-time prediction service behind a maps and ride-hailing product: 1M ETA requests/second, each a (origin, destination) pair, p99 under 100ms, reflecting live traffic that updates continuously from probe data. Cover how you represent the road network, compute routes at scale, incorporate live traffic, and what you precompute vs compute on demand.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.