Tunnels and Covered Routes
GPS needs satellite visibility. Tunnels, underground sections and covered platforms can reduce or block the signal, causing slower updates or lower accuracy.
Metal Train Coaches
Train bodies can weaken signals, especially when you are far from windows. A seat near a window often gives the phone a clearer view of the sky.
Stations and Tall Buildings
Busy stations, bridges and nearby buildings can reflect or block signals. This may cause speed readings to jump or pause for a short time.
Device and Browser Differences
Different phones, operating systems and browsers may report GPS updates at different speeds. Battery saver mode can also affect location performance.