How to deal with Arrivals?

[freenerd]

Currently we have one step in OSRM for the arrival. We are emitting one instruction for it:

{
    "step": {
        "maneuver": {
            "modifier": "left",
            "type": "arrive"
        },
        "name": "Street Name"
    },
    "instruction": "You have arrived at your destination, on the left"
}

To deal correctly with arrivals, we would actually need TWO instructions though, one after the last instruction before arrival, one on arrival:

• In 200 meters, you will arrive at your destination, on the left
• You have arrived at your destination, on the left

There are several solutions here:

1. The client could deal with this exclusively (given that they also already implement distances). The text instruction would need to be in the present then:

• In 200 meters, you arrive at your destination, on the left
• You arrive at your destination, on the left

2. We make osrm-text-instructions alert level aware

• Needs a new ticket, i'm still undecided if and how we should do this

3. We add a new arrivals type in osrm-backend

• This sounds like it would be way too much effort with something that is actually very specific to the layers above.

For now I'd go with option 1.

/cc @MoKob @daniel-j-h @TheMarex @danpat @1ec5 @willwhite @pveugen

[1ec5]

For option 1, we should use the imperative like in every other instruction, not present tense. So: "Arrive at your final destination".

[TheMarex]

Just a note on 3 because I think there is some context needed here on how we encode instructions:

• maneuver is the Maneuver that a driver needs to execute to turn on the current road segment
• everything else in RouteStep references the segment that follows.

That means for the a normal route we would see this a as the last two instructions:

[
    {
        "maneuver": {
            "modifier": "left",
            "type": "turn"
        },
        "duration": 50,
        "distance": 200,
        "name": "Street Name"
    },
    {
        "maneuver": {
            "modifier": "left",
            "type": "arrive"
        },
        "duration": 0,
        "distance": 0,
        "name": "Street Name"
    },
]

The information that the arrival will happen in 200m is already encoded in the previous instruction. Inserting a new instruction type between those instructions would break the convention that an RouteStep describes the route from the maneuver location until the location of the next maneuver.

Hence I agree with @freenerd's assessment that 3 would be a complicated addition to OSRM and IMHO probably more confusing then helping.

[1ec5]

At least in English, the imperative form would be logical (since the user has to actively arrive at the waypoint), consistent with all the other instructions, and compatible with distance-based instructions:

• Continue for 300 feet, then arrive at your destination
• In 200 feet, arrive at your destination, on the left
• Arrive at your destination, on the left

[danpat]

I'm no linguist, but as a native English(AU) speaker:

• In 200 feet, you will arrive at your destination, on the left.

sounds more natural. I don't know why, but "arrive at your destination" alone is awfully....authoritative.

[1ec5]

Sure, that would be a further improvement, but it’s blocked on having distance-based instructions in the first place: #88. Plus, it wouldn’t sound quite as bad if the developer will have had the opportunity to name the destination (#134).

[1ec5]

Here’s a less authoritative-sounding alternative:

• In 200 feet, the destination is on your left
• The destination is on your left

[MoKob]

How about: 🎉 another on time arrival powered by Mapbox (anyone took a Ryanair flight, ever?)
But enough trolling:

I remember hearing stuff like You have reached your destination..

I would not use on the left in early announcements, as it is overly chatty and wouldn't help me early on. Even as you will sounds more natural, @danpat I feel the arrive at your destination might still have the benefit of being less chatty.

So I'd prefer @1ec5 suggestion for early information and possibly two sentences for the actual arrival (here no major maneuver has to take place anymore).

• In 200 feet, arrive at your destination
• You have reached your destination. The destination is on your left.

[1ec5]

Mainly I find the use of present perfect tense (“have arrived”, “have reached”) to be awkward or overly dispassionate. Is it strictly necessary to say “arrive” or “reach”? Maybe this is a difference between what a user would expect in a Web interface versus in voice guidance, or just my American bias. But this feels a lot more natural to me:

• Continue 300 feet to the destination
• The destination is on your left

(or: You made it! 🎉😄)

In any case, #88 means we can only provide one instruction that would be used both before and during arrival. A client such as the Mapbox Navigation SDK for iOS could work around this problem by providing its own pre-arrival string instead of going through this library.