I've been waiting for this feature in an iPhone navigation app for years, but it still hasn't happened. The GPS in my Acura MDX uses this feature for tunnels and such. In order to do this, Waze can, upon losing GPS signal, start taking readings from the accelerometer and average them over a short period of time to estimate changes in speed (speeding up or slowing down) to adjust the speed where GPS signal was lost. The solution is that changes in direction would appear as +/- X values and changes in speed would appear as +/- Z values at a rate of 0.04559g for every mi/h/s change in acceleration. Here is the reference to the UIAccelerometer API regarding this:

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIAcceleration_Class/Reference/UIAcceleration.html#//apple_ref/c/tdef/UIAccelerationValue

I think this feature would make Waze very cutting edge and show that it is a real contender in the navigation app category. I love using Waze and hope that my contribution makes it a better app for everyone.

Generalmente en los túneles el GPS no recibe señal, por lo mismo Waze queda con la ultima posición del móvil que al "no moverse" genera información de trafico denso sin que efectivamente sea así en muchas ocasiones. Al marcar zonas de la Via como TUNEL, Waze podría "ignorar" esa detención virtual y no mostrar la ruta como congestionada, o bien si se puede detectar que el GPS perdio señal y asi no considerar esa info para trafico.

Elaborating on the post of Wim Godden (below), when being in a tunnel, Waze is disconnected from navigation until exiting it at the end. However, sometimes a change in direction has to be made immediately after the tunnel, but then it is already too late to receive in time the next step. I suggest that before entering the tunnel, which is usually more than 800 m before the change in direction, Waze will indicate the next direction to be followed immediately after exiting the tunnel. If not - current situation- when you exit the tunnel (with approx. 100 km/h), you may miss the turn in time. Moreover, this seems to me also applicable for warnings, such as speed cams.

This is not just applicable to tunnels, but to any place where there is a reasonable expectation the GPS signal will be degraded, such as on the lower deck of the George Washington Bridge (NYC).

NOTE: This could likely be combined with the Dead Reckoning idea.

There needs to be _some_ way for Waze to proceed when GPS goes away. A couple years ago, when I had a phone without GPS, another free nav service would present turn instructions one at a time, and the driver would click "next" (or "back") as he progresses. Waze could do exactly the same thing and solve the client problem.

On the route analysis side, knowing that a road segment is a tunnel could prompt Waze to calculate average speed of tunnel segments.

Caching map tiles of route

+

dead reckoning

=

WIN

http://waze.uservoice.com/forums/59223-client-how-can-we-improve-waze-on-your-phone-/suggestions/960901-download-route-map-tiles

Now dead reckoning is what I call a suggestion. On page one is a vague feature request

http://waze.uservoice.com/forums/59223-client-how-can-we-improve-waze-on-your-phone-/suggestions/757024-make-tunnels-navigable

I posted dead reckoning there hoping to stir the pot

Better description here...

http://waze.uservoice.com/forums/59223-client-how-can-we-improve-waze-on-your-phone-/suggestions/2360157-dead-reckoning-when-neither-data-nor-gps-available

^^^

My daily commute is shorter if I take the tunnel, but it is always congested at the time I drive to work. There are other, longer roads that is faster. Since Waze does not work in tunnels, it does not know it is congested.

@DEVs

http://www.gpsworld.com/gps/continuous-navigation-956?page_id=1&print=1

Perhaps the GPS savvy would know more about

* Differential GPS via FM receiver

There are zero map apps that offer dead reckoning:

continue navigation when neither GPS nor data (mobile or wifi) are available. Useful also when insufficient GPS birds viewable.

+ compass
+ accelerometer
+ time

optionally

* orientation (for fixed mounts)

Given availability of map data those are enough to continue navigation:

. in tunnels
. in parking structures
. in box canyons

This is especially beneficial for those who do not have (no longer have) aGPS [assisted GPS] features.

But dead reckoning will benefit even those with aGPS.

Also, if there is a speedcam right after a tunnel Waze will not alert you because it is still "stuck" in the tunnel.

I'd go with the "last known speed" approach for now - it's better than nothing and should not be that hard to implement.

There's possibility to use Kalman filtering, accelerometer, e-gyro and compass sensors in smartphones to improve navigation in tunnels and places without strong GPS signal. See study at http://www.tkt.cs.tut.fi/research/nappo_files/Davidson08.pdf

Some GPS programs (like Nav4All when it was still available) did things like : "After the tunnel, keep right" when there was an action to perform right after the tunnel.
Also, it could just mention "follow the tunnel for <distance>".

I'm in as well, but my suggestion is to don't bother trying to use compass, gyro, accellerometer etc. just instruct the Waze client to stay on the current road with the last known speed (or even a 5% reduction as traffic often slows down just a tad in tunnels), in a sort of "demonstration mode".
Don't bother changing parts of existing roads to "tunnels" either, just let Waze enter "low/no GPS mode" whenever GPS signals disappear - it might happen in city streets surrounded by tall buildings, in dense forrests, in deep valleys, not only in tunnels.

I support this. Lots of tunnels in Norway

Even in short tunnels (never mind the Big Dig), it's easy to lose both GPS and data service. So if a road section were designated "tunnel", the Waze client would know not to panic, and the server would know not to mangle things too badly when the confused data transmission resumes.

great idea, especially with the road type tunnel, and use entry and exit times for avg speed.

Stated: Now I don't know anything about the APIs available to the developers, but accelerometer and gyro capabilities are perfect for tunnels where the Waze application currently has no idea what's going on.

Solution: For tunnels we just need a new road type "tunnel". Waze would know these probably don't have GPS and just use entry/exit times (on junctions) to calculate avg speed on this segment. With that avg speed it can show your car moving in the tunnel, factoring in your speed while entering it. This way waze can guesstimate your position in the tunnel (It's the way other GPS units do it). Special announcements could be triggered by entering a tunnel-road-segment, as would estimated speed. If you DO run into a trafficjam inside a tunnel, Waze will not notice it by reduced speed between GPS-fixes but by absense of GPS-fixes after enough time has passed to reach the other end.

Forum backlink: http://world.waze.com/forum/viewtopic.php?f=16&amp;t=6084&amp;sid=87b1546013dcf65e9cdb65912c68fb82