Thank you Chris (atrophicshiner). I do have comments turned on and I had already seen the comment on the map but thanks for the advice anyway.

I also agree that iainhouse should be consulted should any changes need to be made.

However, I am not suggesting changes to the map. The map seems fine. What's wrong is how Waze has navigated this roundabout incorrectly.

Bearing in mind this roundabout is not unique, Waze should be able to handle it better than this.

The idea that tweaks have to be put in to trick Waze into getting these junctions right makes it clear that something is wrong and the programmers need to take a look.

Thanks for adding the data. It shows that Waze thinks the longer route is 10/14s quicker, which might possibly have been true at the time but was certainly not true today at any time. Would you kindly let me know the same for today when I was there: 1pm to 2pm on Wednesday 18th October 2017. It would be interesting to match the data with what I saw.

Thanks again Chris. That data shows that Waze believes the long way around the roundabout was 10s faster than the cut-through route at around 1pm to 2pm (the time I was there observing it).

What I saw yesterday (and experienced while driving it) was that traffic going around the roundabout was delayed longer than traffic using the cut-through.

The delay would be about 10-15s, though I didn't measure it precisely. I did observe it and kept a fairly good count of the seconds.

When I drove it, the traffic lights turned green and I made my way around the long way. A van which started to enter the cut-through, at the same time as I entered the roundabout, went straight through the next traffic lights. Meanwhile I went around and waited at other traffic lights and saw the van had crossed in front and was speeding off into the distance. The same happened the next time with another vehicle (Mercedes Estate).

Also, I watched the junction for an hour and every single time (each cycle of traffic lights) the traffic on the cut-through went through faster than the traffic going around the roundabout. There were no exceptions. Waze definitely had the data the wrong way around.

Basically. Waze believes the opposite of the facts on the ground.

As you say, the data does account for Waze giving the wrong route.

So the data is wrong and continues to stay wrong because:

• Waze incorrectly assigns the fast times of the cut-through route to the roundabout route (that it recommended to Fastest-Route-Wazers and assumed they had followed).
• The slower times of the Shortest-Route-Wazers are assigned correctly to the cut-through (but this provides an unfair bias).

The slow times are always linked to the cut-through and the fast times are always incorrectly linked to the roundabout. Waze is fooled every time.

In reality, hardly anyone would be actually going around the roundabout, they will all use the cut-through, so there will be no slow speeds to make Waze see things any differently. Left like this it's never going to change. Wazers will forever be given the wrong route here.

The GPS tracks can be fairly accurate and certainly can be accurate enough to determine a change of route. I proved that myself by driving through the cut-through and Waze rerouted me while I was in the middle of the cut-through. However, I do admit that the GPS tracks can be way off too. Probably GPS alone cannot be used to accurately monitor the correct track where roads are in close proximity.

I am sure you are correct that Waze is being misled because the roads are so close together and Waze can't differentiate. What I have said above is just reiterating your point by giving an example which I have verified to know with certainty that Waze is wrong on this.

What I am suggesting is that Waze should be able to handle this situation better. I am sure the programmers would be able to do something to overcome this situation where Waze is consistently wrong.

This example is a good one to review as it is so obvious that Waze is failing.

Some ideas of how it could be put right by programming:

• Use of accelerometers (available on many smart phones) to detect changes in direction and therefore more accurately determine the route taken
• Provide editing tools which allow map editors to reset or influence the data
• Provide an app function to record "better route through junction" (a bit like recording closures where Wazers are given arrows on the map and we tap the one that we actually took and this causes Waze to temporarily use the other turn, if doing so provides a valid alternative route).
• Slow route property (editors add a delay to a group of joined segments in order to reflect reality such that routes utilizing all of those segments in the same order get a time penalty (in this case it would be 15s))

This problem seems to affect many of the complex roundabouts in the UK and is likely to affect similar junctions around the world. Getting this right would make Waze even better and even more dependable.

This problem continues to occur and there are a couple more URs about it. Very clearly Waze is failing to get navigation through this roundabout right most of the time.

On checking the names of the roads I see that alternate names have not been used, contrary to Detour Prevention Mechanisms - Big Detours.

I will put in a request for the alternate names to be added, then continue to monitor the routes to see if it makes any difference.

The simple answer is that Waze believes that the roundabout is faster based on average speed data. At the times of the reports 13:30 & 20:30 on Sunday, Route 1 = the roundabout, Route 2 = the cut-through

Sunday 13:30 Sunday 20:30 This is usually caused by the same problem as having the external bypass lanes, Waze can't always correctly associate the speed data with the cut-through lane as it is so close to the roundabout. There is a Map Comment covering this roundabout (you should always work with these turned on in the layer menu).

Iainhouse has already added some tricks to encourage Waze to use the cut-through. Any alteration / tweaking should definitely be done with his consultation

I'd say it is more the limitation of the technology in mobile devices. Waze relies on GPS to know where you are, with a +/- accuracy and roads that run close together there is a limit to what can be done.

I'm using Route Speeds script to show the hidden speed data. For a typical Wednesday between 13:00 & 14:00, roundabout = 03:52, cut-through = 04:02. This does not account for realtime speed data that Waze will also use.