Subway Speed Test — Real-Time Train Speed via GPS Underground & Above Ground

What This Tool Does

This tool turns your phone into a subway speedometer.

It measures:

• Ground speed
• Distance traveled
• Time and stop segments
• Speed windows between stations

Works directly in the browser, no downloads or login.

Why GPS Beats Built-In Train Displays

Not all subways have speed displays, but some systems do (Japan, Dubai, Hong Kong MTR).

Built-in displays often show track speed limits or scheduled speeds, not real ground speed. GPS measures actual speed relative to Earth's surface.

This tool gives you the true velocity your train is traveling, not what the system thinks it should be doing.

Subway vs Metro vs Commuter Rail

Many riders don't know the difference:

• Subway / Metro — Heavy rapid transit designed for frequent stops and fast acceleration. Operates on dedicated track, usually underground or elevated. Typical cruise: 50–80 km/h.
• Commuter Rail — Longer distances between stations, higher top speeds (100–160 km/h), often shares track with freight. Fewer stops per kilometer.
• Light Rail / Tram — Surface-level, slower acceleration, mixed traffic in some sections. Top speeds rarely exceed 70 km/h.

Ground speed profiles differ significantly between these modes. This tool works on all of them wherever GPS signal is available.

Reality of GPS in Subways

When GPS signal drops, the tool pauses and resumes automatically when satellites return.

Signaling Systems & Speed Governance

Subway trains operate under signal control systems that determine speed:

• Fixed Block — Conservative, longer headways, speed governed by block occupancy
• Moving Block / CBTC — Allows higher throughput, smoother acceleration, tighter speed consistency
• GoA 3/4 Driverless — Precise speed hold and automated braking with no human intervention

CBTC systems (used in Paris, Hong Kong, Dubai, Singapore) maintain tighter speed consistency compared to older fixed-block systems like NYC or parts of London.

Modern driverless metros often achieve more consistent cruise speeds with less variation between runs.

Why Riders Use This

Different subway riders use it for different reasons:

Famous Subway Max Speeds by System

Documented maximum speeds for major subway systems worldwide:

Actual speeds vary by line, rolling stock, and signal conditions.

Typical Cruise Speed Ranges

Subway performance varies by system:

Outdoor commuter rail can exceed 120–160 km/h, but that's not subway.

Acceleration & Stop Profiles

Subways operate in stop-burst-stop patterns:

• Strong acceleration leaving stations
• Short cruise segments
• Heavy braking into stations
• Dwell time at stops

Average speed is always much lower than peak:

How Speed is Measured

Same rules as the Train Speed Test:

GNSS constellations:

• GPS (US)
• Galileo (EU)
• GLONASS (Russia)
• BeiDou (China)

Velocity derived via Doppler shift at higher velocities for accuracy.

Subway situation demands:

• High sampling rate
• Resumption after tunnel blackout
• Pause during zero-motion dwell time

Urban Signal Limits

Dense cities can create GPS impairments:

• Urban canyon effect
• Multipath reflections
• Partial sky view
• Station roof obstructions

These do not affect speed once the train is fully above ground.

Subway Types

Not all subways are the same:

Tool works for all types as long as satellite visibility exists.

Safety Notes

• ⚠️ Do not stand near open doors to get GPS reception
• ⚠️ Do not hold phone outside moving train
• ⚠️ No interference with train operations
• ⚠️ Respect system filming/usage rules if applicable

Device Support

Coming Soon

• Segment-by-segment analytics
• CSV/GPX export for transit mapping
• Auto line detection via city geofencing
• Station dwell analytics
• Leaderboard for system comparisons