Walk towards a corner with iseeido’s street directions on, and about 40 metres before it the phone tells you what to do there. At walking pace, that is roughly half a minute. It is enough time to find the turning, and not so long that you have forgotten the instruction by the time you reach it.
Until build 19, a drive got the same warning, at the same 40 metres. At 50 km/h, 40 metres goes by in about three seconds.
A distance that was really a time
The code that sets the 40 metres explains it in time: at a walking pace of about 1.4 metres a second, it is about half a minute. In a car the distance stayed the same, and the half minute shrank to almost nothing.
Driving is warned by the clock
Since build 19, when you choose Drive, iseeido works out its warnings from how fast you are going. It takes the speed reported with your latest location and, where the stretch before a turn is long enough, speaks twice for it.
The first warning comes about 30 seconds ahead, with the distance, in the units your phone uses: “In 0.3 miles, turn left onto…”. The turn is said again about 6 seconds before you reach it. This time it is only the turn. Google’s instructions sometimes carry a second line, such as a landmark you will pass, and seconds before the turn that line would only delay the part that matters.
Both moments are turned into distances, so the faster you go, the further out they start. If the phone has no speed to go on, iseeido assumes 13.9 metres a second, which is 50 km/h, a town speed.
Limits at both ends
At a standstill, 30 seconds of travel is no distance at all. So the first warning never comes closer to the turn than 300 metres, and never further out than 1.5 kilometres. The second is held between 50 and 200 metres.
- 40 mon foot: one warning, about half a minute at walking pace
- 30 sdriving: the first warning, between 300 m and 1.5 km out
- 6 sdriving: the turn said again, between 50 m and 200 m out
The arithmetic at four speeds
- At 20 km/h, 30 seconds is 167 metres, so the 300 metre floor applies and the warning comes about 54 seconds ahead. Six seconds would be 33 metres, so the second call is held at 50 metres, about 9 seconds out.
- At 50 km/h, the warning comes 417 metres out, and the turn is said again at 83 metres.
- At 108 km/h, they come at 900 metres and 180 metres.
- From 120 km/h, the second call stays at 200 metres, so it comes a little less than six seconds before the turn. The first warning reaches its limit of 1.5 kilometres at 180 km/h.
Said in good time, and not twice
iseeido keeps track of what it has said. If a turn was announced while you approached it, it is not announced again as you take it.
That memory now also survives a new route. Before build 19, every time a fresh route arrived, the spoken directions started over, repeating the road you were on and the turn ahead. Now, when a fresh route follows the same way, each turn already spoken is matched to the same turn on the new route, by where it is, to within 25 metres.
Walking, cycling and public transport keep the single warning at 40 metres.
What it means with the phone in your hand
On foot, nothing has changed: one warning, about half a minute before each turn. In a car, the first warning now comes about half a minute ahead, or earlier in slow traffic, much as it does on foot. The turn itself is said again just before you reach it. The drive still ends at the door you marked.