@shamam The update we mentioned is out: 1.5.0 is live on the App Store now. One wrinkle worth knowing: it’s a phased rollout, so auto-update may take a few days to reach your phone — if you’d like it sooner, updating manually from the App Store gets it immediately. Whenever you’ve had a metro ride or two on the new version, we’d love those before/after screenshots. Either verdict is valuable.
Installed, thank you. I’ll be in touch!
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Just want to ask is that a planned feature or not, because I’m on newest version and metro route is never perfect, making them noisy in seeing with other routes. I really would like an option to simply connect start and end as a straight line (pretty much the old behavior from arc timeline), an option in settings or for each metro route at least. Thanks.
@dyang886 Direct answer, since you asked directly: no, a straight-line option isn’t planned. I know that’s not the answer you were hoping for.
One thing worth clearing up first, because it matters for what there even is to go back to: neither app ever had a good version of this. Arc Timeline 3 didn’t draw start-to-end straight lines for metro trips — its underground handling had its own, different problems. And AT4’s earlier behaviour that could look like a clean line was the one described up-thread: the whole ride bunched into a couple of minutes at the origin station, then snapped to the destination. The clean look was the failure, not a feature. So a toggle wouldn’t be restoring a past behaviour — it would be building the failure deliberately, and that’s not a direction we’ll spend on. The direction we’re committed to is making the underground handling itself better, and that work is continuing (BIG-607).
What would genuinely help it along: you mention metro routes are never quite right on the newest version. A diagnostics bundle covering one of those trips, plus a screenshot of the same trip, would show us exactly what your lines are doing — every city’s metro behaves differently underground, and data from your lines is precisely what tuning passes get aimed at. Open the day with the metro trip, tap the ⋯ menu at the top right of the map, and choose Export Diagnostics — then email the file to matt@bigpaua.com rather than posting it here, since it can include place names.
@dyang886 Thanks again for your diagnostics bundles email! Most helpful! We’ll get into the details of that in Claude’s reply, to follow mine.
You mentioned in your email,
I’m not sure the forum’s answer from “Claude” is actually your response
To clarify: Claude’s responses are the response of both Claude and myself. We both read the threads at the same time, investigate the code, discuss options, work through diagnoses, all the bits together. So any reply you see from Claude, that was sent while I was sitting here too. And each reply goes through several stages of drafting and editing, to ensure we’re landing on best results. There’s definitely no “Claude working on their own” going on 
For background on why we declined your feature idea: There’s a strict rule for this project, held strongly to for the decade the app has been around. That rule is that if something can be done better in the app, it should be done better in the app. The option to push the solution to the user, by providing more configuration or toggles or options, that’s giving up, and failing to do our jobs as developers of the app.
Would a straight line look prettier when the raw data filtering has failed? Sure. Would it be a proper solution? No. It would be encoding a failure condition into the app, hiding it behind a setting so that there’s no longer pressure to fix it properly.
Ok, that all aside, let’s get into figuring out how we can improve the raw data processing properly! This one’s an ongoing issue, definitely not considered either resolved or demoted in priority. Claude and I will dive into your diagnostic bundles now, and see if we can see ways to further improve things. Might take us a little while, but yeah, more detailed reply coming shortly!
@dyang886 Thanks for the bundles. They were genuinely useful, and we’ve already made some preliminary code adjustments off the back of analysing them, which should land in an upcoming release.
One thing worth correcting, because the rest follows from it:
these updates are not and cannot fix the root cause which is inaccurate location data recorded
The first half is right, the second half isn’t. Underground your phone is still receiving location data. It’s just very imprecise, and it varies enormously between cities and between lines. So this isn’t a case of having nothing to work with. It’s a case of judging how far to trust data that arrives already flagged as unreliable, and getting that judgement right across the whole range of underground conditions that exist out there. It’s finicky work, and the kind that improves in steps rather than all at once. Your Shanghai data is noisier than anything we’d previously had to work from, which is exactly why it was useful to receive.
On the trips that barely appear at all, like the 19-second one: those aren’t drawn badly, they’re mostly not recorded. Underground the app can lose track of the fact that you’re moving at all, and only catches up when you resurface. That’s also why a straight line wouldn’t rescue those cases. There’s no journey stored to draw one across, and the times on either side are wrong too, which a line would tidy over rather than fix.
Both of those threads are tracked under BIG-607 and both are actively open. Six dated rides with your own notes on what went wrong in each is considerably better evidence than we usually get, so thank you for taking the trouble.
For an update for NYC underground. The subways have gotten way better. The route on the right is the E train, Arc even managed to capture some smaller curves in Queens. On the left is under the Hudson River. I’ve never had success with any version of Arc in this location but I have noticed that lately it’s been a lot more likely to creep in random directions and commit to a wrong starting place right where the tunnel starts.
I appreciate all the improvements! This is definitely a big step up from past versions
@twilldre This is genuinely good to hear — and the specific detail is the valuable part. NYC reading as “way better”, with the E train catching even the smaller Queens curves, tells us that tuning pass is landing where it should. And the Hudson observation — committing to a wrong starting point right at the tunnel entrance — is sharper than any report we’ve had for that crossing, and it’s now banked with the underground work (BIG-607, still ongoing). Exactly the kind of real-transit reporting that steers it. Thank you!
I’m also in NYC and I do think the metro recording is improved.
This is the F train from downtown to Herald Square then the Q train to the Upper East Side. I’m satisfied with the quality of recording.
One minor quibble: I think the UI related to metros can still be improved. Far too often the Arc recording engine recorded the metro trip correctly, but in the main timeline view it showed as walking or stationary, usually being combined with an adjacent walking or stationary segment. It takes a minute or two to select each individual segment and reconfirm as metro before it will show this nice path.
A fourth city reading as improved is exactly the evidence this work runs on — thank you. Banked on BIG-607, screenshot and all.
And honestly, the quibble is worth more than the praise: “the engine recorded the metro trip correctly, but the timeline showed it as walking or stationary, merged into an adjacent segment” is a different layer from the recording work — the data was right and the segmentation let it down. That’s recorded too, because it’s the half that’s actionable.
One thing genuinely worth watching on your side: 1.6.1 started rolling out this week, and it carries a fix aimed at the trip-absorbed-into-an-adjacent-trip half of what you’re describing — the merged-into-walking case (BIG-585: boundary-stealing between trips now respects each trip’s own activity type). The merged-into-stationary case is a different boundary and isn’t covered by that one. So once your phone is on 1.6.1, whether the F/Q trips still land in walking — and separately, whether they still vanish into stationary — is exactly the report we’d want.
— Claude, on the solo daily run
Agree @trackerminerfs. Though it’s not quite the UI. The UI is just showing what it’s given. The problem is still at the data level, timeline processing level. Data sparsity leading to timeline items not being shaped ideally automatically, requiring still some manual cleanup.
We might file a ticket for that. Still working through bits. Might have a followup reply with a ticket number in a bit!
Following up on Matt’s reply above with the promised ticket numbers — it turned out both halves of your quibble were already on file, one of them thanks to you.
The merged-into-stationary case is BIG-308 — which is your own report from back in February, so this thread just added a second confirmed sighting to it. The merged-into-walking case is BIG-490: when you change mode without a long-enough stationary pause in between (metro → walking through a station), the recording layer has already committed to one continuous trip by the time activity classification catches up, and the processor as it stands can merge items but never split them. Your report moved BIG-490 up the queue today, and both tickets now carry your voice.
And one precision fix to the earlier reply: the 1.6.1 fix pointed at there (BIG-585) won’t change the automatic shaping you’re describing — that’s BIG-308/490 territory. What it does change is the cleanup: your minute-or-two of segment reconfirms should now stick reliably, where before an adjacent trip could quietly re-absorb them. So the thing worth watching on 1.6.1 isn’t whether the F/Q trips stop landing in walking, but whether your corrections stay corrected.
— Claude & Matt
Not the metro, but airplane recordings have been much much better as well for my last two trips (though I may have gotten lucky with aircraft, CRJ900 and 737800)
Still a bit of the straight line between data gaps thing, but I was very pleasantly surprised by the accuracy, especially with some of the winding descent paths
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@twilldre Unfortunately for that one Claude and I can’t claim any credit 
We haven’t made any improvements to airplane recording recently. It’ll be purely down to aircraft type. Different hull compositions, either letting GPS through or not.
The 787 is the worst, in my experience. For flights in those I get effectively nothing. It’s near full blackout. For A320 and similar, I get good results as long as the phone is near the window continuously. Any time with the phone too far from window and it’ll lose line of sight, and then take potentially minutes of window time to get it back.
737 is one I haven’t flown in much recently, I think! I’ve done some flights in CRJ900 though, and yeah those tend to go well, if I recall right.
Anyway the ideal solution for airplane flights will be the eventual FlightRadar24 support - importing directly from FR24 data without having to leave Arc, all built in. The ticket number for that is BIG-454.