Ghost Closures?

Map Editors Community United Kingdom
1

I’ve raised an issue on the Off and On thread about a diversion off and on the Hanger Lane Gyratory https://www.waze.com/forum/viewtopic.php?f=55&t=56560&sid=591a10e5a1efb1909d2335d1bd7cc5e0&start=340#p1580861

Found another possible “ghost” closure today

Traveling from Canary Wharf to Manchester usual route given is A13 (although I usually take A12 instead), North Circular, M11, A14, A1, M62

Today (06:30) it came up with A13, North Circular, M1, M6, M62 as being slightly faster. Unusual but possible.

I decided to take my usual route anyway, but once on the A12 it started telling me to divert via the Walthamstow turning.

I continued up the A12 despite this, and could see an accident marker, 2 police markers and slow traffic on the North Circular just west of the M11 junction, which I assumed at the time was the cause of the alternate route, but the exit to the M11 clear.

However Waze was routing me through the carnage up to the next junction on the North Circular and then back to the M11.

Again ignoring the app I took the filter and flyover onto the M11 and once I had cleared the flyover it rerouted again back to the familiar route and an ETA 20 minutes earlier then the previous route it had offered.

Only explanation I can see is that it thought the flyover was closed, but there was no indication of that on the app (or physical evidence on the road)

The app had rerouted as I took the filter off the roundabout, whilst the flyover was visible on the screen, so there is no way the route was in place and then the closure lifted (unless of course the app wasn’t displaying the closure correctly).

I’m wondering if this and similar issues are causing some of the routing problems that are being reported.

2

I really don’t know this area, so have no experience of driving along these roads or what normal traffic levels are like. Although I’m a London-based editor, I’m south of the river and that area is in the “there be dragons” part of the map as far as I’m concerned!

If previous users were experiencing slow traffic on the entry to the M11, or if a user broke down but didn’t turn the app off, thereby creating a blockage as far as Waze was concerned, it’s possible that Waze thought it was quicker to continue on the N Circular to the next junction then return and approach the M11 from that direction, even with the delays. This would result in Waze offering you the route it did rather than the direct one onto the M11. Of course, once you drove through, you reset the traffic data and improved routing for everyone following behind you.

Remember that Waze won’t show “slow” traffic on the app if that’s the normal traffic flow at that time of day, (unless a user reports a jam) and I wonder whether this is an example of Waze routing round a phantom traffic jam rather than a closure.

3

I had a strange routing myself.
I was trying to head home from work, the route was showing as M5 south to Junction 16, left on Gloucester Road to the next roundabout, U-turn on the roundabout, back alone Gloucester Road, re-enter M5 North, Immediately take the M4 Slip, Then East on the M4.
When I saw this I attempted a search of an alternative route, which came back as M5 South to Junction 15, then M4 East (5 minutes shorter and saving a few miles)??
The old route did not take me along any routes (except a short ramp) that the new route did not use???

4

That’s something to consider (I didn’t know that slow traffic doesn’t always get shown although it makes sense of other things I have seen now.)

In this case though average traffic speed (at around the same time) over the flyover is probably above the speed limit, a lot of people ignore the 50mph limit and treat it as though they are already motorway driving.

5

That may well be, but if there’s one Wazer who’s stopped on that segment and leaves Waze running, with no other Wazers going by, the traffic data is going to reflect the stopped vehicle as traffic at a standstill and route you around that blockage if it can.

You don’t say what time of day this was. I know the M5/M4/A38 junctions can be incredibly busy and slow, with queueing for the A38 exit starting all the way back to the M32 junction in the morning peak. I think it would be highly unusual to get a combination of stoppages to produce the route you first got. The fact that you were able to get the direct route when you searched for an alternative route shows that the traffic data changed even in that short time, resulting in a better routing.

Waze does recalculate routes every 10-15 minutes, so you’re quite likely to see messages saying that traffic has eased and your journey will now be shorter, or a faster route has been identified, or traffic has built up and you’ll experience a delay. These are all results of crowd-sourcing traffic data in real time.

When you do see an odd route, see what others are available and, if the first route is still the fastest, stick with it until you can see the traffic conditions when you get to the chance to avoid the odd routing and take the direct route if it’s available. You reset the traffic data on that “blockage” which benefits every one else.

Waze will only find out current traffic conditions if users are driving along those roads. Someone is the first user into a traffic jam and suffers. Others are routed around until someone takes a chance and finds the jam has dissipated, prompting Waze to start offering that route again.

6

This was in reference to

So according to you, if the traffic flow at that time of day is generally much better than the current situation (1 wazer stopped on the hard shoulder) then it should have shown as slow traffic in the app.

7

Re M4/M5
I’ve identified a problem with the speed data between J14 and J15 southbound which means Waze believes this stretch is very slow, particularly when exiting for the M4, and so we’re seeing some odd detours. I’ve made some edits which will hopefully reset the data after the next update… fingers crossed.

8

Oops! :oops:

I thought I posted a reply about this to you shortly after your comment, but I clearly failed to hit send or something and didn’t. My apologies for not spotting that the ramp to the M11 should have been red. I was trying to offer the simplest solution then tripped over my own feet.

Waze is currently routing along the direct link from the A406(N) onto the M11(N). An alternative route via the Waterworks Corner roundabout is offered, which will currently take 5 minutes longer. As a result, I think we can be confident that the odd segment traffic data you encountered which resulted in the alternative route being selected has now been reset and Waze is routing as expected.

9

My best guess at the moment is that the map server and the routing server are separate and the routing server isn’t being updated quickly.

So there could well have been a blockage/closure that the app displays correctly (because it has already cleared) but the routing server is still using the old data.

There may have been a similar issue on Friday at the junction of A14(E)/A1(N), fairly sure there was a closure as I passed going South, on the way back it was routing me around this area until 07:40 which seems late for an overnight closure (although it is possible that the closure ran late or wasn’t removed until that time)

10

Another one today…

M6 Southbound overnight closure Jn 12 - 11

This was showing on the matrix boards on the way down, but due to getting caught behind a pile up I didn’t get down there until after it had reopened.

Waze app showing not showing the road as closed (red and white stripes) but still routing around

Shut down and restarted but still routing as if the route was closed, even routing me off and on at junction 11 to get round the last bit of the ghost closure.

So either it thinks there is a closure but isn’t displaying it or it knows the closure has finished but is still routing round the area.

11

Speculation:

  1. there was an accident, a stretch of motorway got very slow (or stopped), with at least one Wazer stuck in it. Waze noticed the slow speed, flagged “traffic” to itself, and started routing people around it.
  2. the road then got closed on Waze (and on the ground)
  3. the road then got reopened, both on Waze and on the ground. But the last information Waze had about traffic speeds dates from (1), so it continues to route people around, until …
  4. a Wazer ignores directions and continues on the motorway at speed, wiping the “traffic jam” to the benefit of future users.

If this is the case, then Waze could benefit from the deletion/expiry of a closure automatically wiping recent “slow traffic” history. But it may well be that it already does, and my speculation is unfounded.

Ian

12

I’m assuming it was a planned closure (it was closed in the same location the previous night)

There’s quite a few of these night closures on the M6 at the moment.

Unusually slow traffic should also show up on the app

13

Closure on the A1(M) Jn 36 this morning

Looked like a planned closure physically, only closing the main road under the junction - diversion by on off-and-on.

Waze diverted me off-and-on as expected, but no sign of the road closure on screen.

Any way to find if Waze was informed of this closure (I believe we’ve got some sort of automatic update) or if it’s just routing people based on other driver’s actions.

14

The A1(M) (S) at J36 was indeed closed overnight, from Mon 21:25 until Tue 05:05.
I don’t know what it wasn’t showing on your app.