Check a Bus's Speed From Your Seat
Is the coach doing the motorway limit? How slow is the crawl through the centre at rush hour? The bus speed test on this page answers both with your phone's GPS: the reading comes from the satellites overhead, not from the bus's own instruments. It works on city buses, double-deckers, long-distance coaches, school buses, minibuses, airport shuttles and trams that run on the street.
A bus trip is stop-start in a way a train or a motorway drive is not, so the useful numbers are different too: not just how fast the bus goes, but how much of the trip it spends standing still.
Moving Speed and Door-to-Door Speed
The average under the dial is the moving average: distance divided by the time the bus was actually moving. It tells you how fast the bus travels between stops. The figure that decides how long your trip takes is the door-to-door average: distance divided by the whole journey time, stops and queues included. To get it, divide the distance under the dial by the journey time.
The table shows how far apart the two can be on a 12 km route where the bus does 30 km/h whenever it is moving. The moving average stays at 30 km/h throughout; only the time at stops changes.
| Time at stops | Journey time | Door-to-door |
|---|---|---|
| 0 min | 24 min | 30 km/h |
| 5 min | 29 min | 24.8 km/h |
| 10 min | 34 min | 21.2 km/h |
| 15 min | 39 min | 18.5 km/h |
| 20 min | 44 min | 16.4 km/h |
With 20 minutes at stops, the bus spends 45% of the trip standing still, and its door-to-door speed falls to 16.4 km/h — even though it was never slower than 30 km/h while moving.
How Long Did the Bus Spend at Stops?
The trip numbers answer this too. Divide the distance by the moving average to get the time spent moving, then take that away from the journey time. On a 9 km trip with an average of 27 km/h, the bus was moving for 20 minutes; if the journey took 35 minutes, it stood still for about 15. Traffic lights and queues count as stops as well, so this is the time the bus was not moving for any reason.
Timing Your Route Against the Timetable
Press Start as the bus pulls away and Pause as you step off. The journey time is your trip as it actually ran, ready to set against the timetable; the distance tells you how far the route really goes. Ride the same route at different times of day — before the rush hour, in it, and in the evening — and the moving and door-to-door averages show where the time goes: a bus that is quick between stops but slow door to door is losing its time standing still.
Why the Reading Wobbles in Town
In a city centre, tall buildings on both sides of the street hide part of the sky and bounce signals off glass and concrete before they reach the phone. The reading can wobble by a few km/h, or lag behind the bus as it pulls away from a stop. Out on wider roads and in the suburbs it settles. Bus stations, underpasses and covered interchanges drop the signal altogether; the dial holds its last figure, dimmed, until the bus is back in the open.
Coaches on the Motorway
On a long-distance coach the dial often stops rising at about the same figure however clear the road ahead: that is the speed limiter, not the driver. The rules behind it, and the national speed limits for buses and coaches in Great Britain, are in the table below, with their sources. For a long trip, plug into a USB socket if the coach has one: GPS and a screen that stays on use battery quickly.