Much information about how this could be done in https://waze.uservoice.com/forums/59223-waze-suggestion-box/suggestions/2360157-dead-reckoning-when-neither-data-nor-gps-availabl

I guess the "WIP" note is related to Falcon. I guess Falcon makes use (at least) of the cellphone acceleration information. This could be used to match position with curves on the road, at least when those curves are steep, and/or separated.
The biggest problem happens when (somehow) you get spurious GPS samples (this happens in a major tunnel in Madrid, ie. M-30) which takes you OUT of the tunnel. This shouldn't be possible unless you have an exit, and the rest of input (acceleration, again) matches somehow. This breaks any Falcon improvement (once you are taken out the tunnel, road geometry can't obviously be matched).

Most ODB2 dongles present speed data, etc. In a standardized format. Together with acceleration sensors, etc., this should be feasible

The problem is, a device using the sensors you mentioned cannot determine whether you are moving, only accelerations or rotations on 3 axis.

Please start first with navigation based on speed entering tunnel (as mentioned very often in the past). A simple calculation. Later on you can improve every detail you want.

And be able to report a problem even if you are offline or you have a weak signal or none at time of reporting problems.

Very interesting to have those beacons butI I don't foresee in the near time to get them in Spain. In the meantime a simple speed Base could be implemented.

Cannot wait for beacons worldwide please. Add tunnel navigation as gmap at least, with simple speed based prediction

Implemented in Google maps but why not in Waze?

Note that "Here we go" and "Google" have the navigation in tunnels available for a very long time! And it's very useful!

En effet cala manque. Ca fonctionne très bien avec Here we go et Google maps. Nous avons de nombreux tunnels à Paris, avec des embranchements à l'intérieur et c'est absolument indispensable.

Now there is an IC package to accomplish this, lazy google hoard:

U-blox ZED-F9K
"
Continuous lane accurate positioning under the most challenging conditions

. Decimeter level accuracy for automotive mass markets
. Turnkey multi‑band RTK solution with built‑in inertial sensors
. Low latency position update rate of up to 30 Hz
"

Please. Every time I drive through a tunnel, Waze looses its mind.

The speed would be the average 10 seconds before the tunnel. Just a suggestion.

Google maps has it but it is not not available on Waze

I got stuck in Paris and lost and hour, due to Waze losing connection in tunnel. Would have been really handy to have this along with lane guidance.

Yes why can't they just have the position move through the tunnel at the same speed as was detected before the car entered the "tunnel" segment. Will be close enough and will result in getting the correct exit instructions. If you get held up in the tunnel then the position would stop when the position reaches a non-tunnel segment and GPS is not available. Seems easy to implement to me, no beacons, no attempting to simulate an inertial navigation system....

There is a strange solution Waze has locked on, Beacons, which is only available in a few tunnels in the world.
Give Waze support for countdown navigation, for example, using last known speed alternatives if Waze is connected to an Android Auto car, use information from the car for navigation in a tunnel. Beacons will never be installed World Wide.

TomTom app does this and it is incredibly accurate. Would help a lot.

Actually, i am not shure if this also applies to Waze, but some routes google maps, i dont know where to exit, as the map shows two lanes going to one. Inside the tunell it does not update the position. At least when entering a tunell you should be shown the exit you need to take. It is actually quite dangerous, as you try to get the text route while driving inside the tunell.