Design ETA Prediction

Hard45 min
1 / 30
understanding9 min read

Problem Statement: Real-Time ETA Prediction

Problem Statement: Real-Time ETA Prediction — ETA prediction interview depth

Problem Statement: Real-Time ETA Prediction

Phase understanding — Uber/Google-class ETAs for ride-hailing and logistics: pickup, en-route, and arrival minutes with calibrated uncertainty.

ConcernDecision
1Predict minutes-to-arrival for active trips and pre-match offers
2Blend map routing, live traffic, and historical priors per metro
3Expose confidence intervals, not a single opaque integer
4Refresh ETAs on GPS cadence without melting feature stores

Design note (1)

Uber/Google-class ETAs for ride-hailing and logistics: pickup, en-route, and arrival minutes with calibrated uncertainty. Watch for candidates who quote a single seconds integer without p90 band or staleness flags.

Operations: Runbook: page when urban MAE > 2.0 min for 10 minutes or calibration drift > 8%.

Edge cases: Roaming driver crosses region mid-trip — pin features to trip home region until replan. Duplicate GPS batches must not double-count speed aggregates.

javaOne Dark Pro
1public record EtaPrediction(String tripId, int p50Sec, int p90Sec, String modelVersion) {}
pythonOne Dark Pro
1def mae_minutes(actual_sec: float, pred_sec: float) -> float:
2 return abs(actual_sec - pred_sec) / 60.0
typescriptOne Dark Pro
1export interface EtaQuote { p50Seconds: number; p90Seconds: number; staleFeatures: boolean; }

Why interviewers care

ETA Prediction interviews reward crisp scope, explicit trade-offs, and failure stories—not generic microservice diagrams.

Interview checkpoint

Name one failure story for Problem Statement: Real-Time ETA Prediction that proves you understand real outages, not happy-path diagrams.

Key Highlights

  • Predict minutes-to-arrival for active trips and pre-match offers
  • Blend map routing, live traffic, and historical priors per metro
  • Expose confidence intervals, not a single opaque integer
  • Refresh ETAs on GPS cadence without melting feature stores
pro tip
For Problem Statement: Real-Time ETA Prediction, state numeric SLOs before naming ETA API.
interviewer loves
Quantified Predict minutes-to-arrival for active trips and pre-match offers with explicit degradation ladder.
common mistake
Treating pre-trip quote latency the same as on-trip 5s refresh path.
trade off
Residual ML accuracy vs p99 — cap model depth on hot path.

Section Rescue Kit

Buzzwords to use:

Quantile ETAH3 spatial index

Safe statements:

  • "For Problem Statement: Real-Time ETA Prediction, I'll separate vendor base time from ML residual before storage choices."
  • "Calibration on holdout prevents systematically optimistic ETAs."
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