Garmin Tunnel Mode

 

Anyone know how Garmin Tunnel Mode works? I thought it might be Dead Reckoning, but my speed in the tunnel changed and the speedometer on the GPS unit did not. I have a Drive Assist 50 if that matters. Just curious how it worked.

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Well ...

My Drive 50 and others I have just freeze the speed when in a tunnel ...

--
Where there's a will ... there's a way ... DriveSmart50LMT-D, Nuvi 2508LMT-D, 1490LMT, 1310, Montana 650T, Etrex 20

Tunnel Mode

Never heard of it.

Tell me more, please.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.

Basically,the unit uses the

Basically,the unit uses the last speed it was able to calculate move the cursor across the map until it receives enough data from the satellites to recalculate.

Even if you come to a complete stop, the curse will continue, as there is a lack of data to tell it any different. I suppose If you remain stationary long enough, it well throw up a loss of signal error and stop moving the cursor. I've never had that happen.

I expect shortly after moving the cursor to the end of the tunnel and not getting any satellite data is where that will occur.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

Thanks

That's interesting, thank for the info

--
2597 Sometimes I wonder..."Why is that Frisbee getting bigger?"...and then, it hits me.

Never Saw That

Mine just loses satellite reception.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.

Speed

In my car the speedo reads in kilometres. I can change that to miles but it screws up my fuel record keeping.
So to read Mph when I drive several thousand miles in the US every year, I change the Garmin instead.
I've yet to be in a tunnel where the loss of a speed output has bothered me!

--
Nuvi 350 long gone, Nuvi 855LMT Retired now, Nuvi 2797LMT, SmartDrive 50 LMT-HD, 3790LMT now my daughters. Using Windows 10. DashCam A108C with GPS.

Are tunnels that long, have many turns?

Now we've got lost in caves a few times, but can't remember ever getting lost in a tunnel?

F W P

First world problems.

grin

Wait for the news report

Wait for the news report that a car caused a pile-up in a tunnel because the GPS said he was going 55 and the speed limit signs were 35, so he slammed on the brakes. Not his fault - blame the GPS....

--
I never get lost, but I do explore new territory every now and then.

Tunnel Mode?

I haven't heard about this feature either.

Don't Work

My GPS loses satellite reception in a tunnel and just does nothing. And any GPS data the display is showing is probably wrong. Barometer info is still good if it is calibrated. That's usually fun to see negative elevation numbers.

I was traveling through a tunnel in NYC, and just outside the exit of the tunnel had like 6 choices within about 200 ft, no time for the GPS to get position lock and recalculate.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.

Tunnel Mode

what models have this mode? I have never seen it on my Drive 60.
Thanks for the info

--
Garmin Nuvi 765T, Garmin Drive 60LM

3597 is one that has tunnel mode

It appears that as the maps are updated to include tunnel data, the GPS devices with "tunnel mode" estimate your position within the tunnel based on your speed at the entrance and show you moving though it. I've not noticed a loss of signal message when in those as I assume the tunnel data suppresses the message. If there was a traffic slowdown in the tunnel, I expect it would post a message if you haven't arrived at the exit and reacquired the satellites in the expected time.

--
"There's no substitute for local knowledge" nüvi 750, nüvi 3597

Models

Jery wrote:

what models have this mode? I have never seen it on my Drive 60.
Thanks for the info

Darn, I've searched the internet and Garmin and from what I see, there is no list of Garmin models with tunnel mode. Maybe we could start a new thread and have users report on the models with it.

For those with older or other models that don't recognize tunnels, the models that do respond to tunnels also turn to night-mode inside the tunnel and back to day-mode when exiting the tunnel. Here's a YouTube of what I think is a DriveSmart 61:

https://www.youtube.com/watch?v=8CZZx4iAQv4

Tunnel mode works until you

Tunnel mode works until you have a significant change of speed in the tunnel. Here in Pittsburgh, I have lots of opportunities to test the function. Normally it calculates progress through the tunnel based on entrance speed. Most of the time it seamlessly moves through the tunnel and picks up the satellite signal at the other end. If traffic stops in the tunnel, the GPS will eventually indicate Signal Lost.

Thanks, good to know

Thanks, good to know

Tunnel Mode

I have no information to offer on Garmin Tunnel Mode. Sorry. Will look at other responses.

--
romanviking

Mine also looses reception

All of my garmins have lost reception since 2006. Newer ones keep image of area on screen

My 3590

Goes into tunnel mode as well as my 3597. It is a useful feature in that it makes seeing the screen a lot easier when entering a tunnel. It works pretty good. Enter the tunnel, it darkens, come out of the tunnel, it brightens back up. (Just like when it goes into night mode.)

--
It is impossible to rightly govern a nation without God and the Bible. ----George Washington

New thread

I've started a new thread requesting input on models that offer Tunnel Mode which with luck will be useful enough to become a FAQ soon:

http://www.poi-factory.com/node/48315

Wow..

Wow..never knew that feature existed?

tunnel mode with my 2360 (2465TW) and later models

My 2360, 2495 and 3597 all have the tunnel mode.

It is much less distracting when you exit a long tunnel when the GPS reacquires the satellite signal. Without it, there would/might be a sudden jump of the map on the display.

On the built in nav in my

On the built in nav in my Corvette when in a tunnel or when buildings or mountains block the GPS signal it still navigates using the cars speed sensor and its built in compass until the GPS signal is restored so it is pretty much dead on the actual route position the entire time. So it navigates correctly even without a GPS position lock.

On my Gamins that I had they appeared to just guess the position based on the speed you were traveling when the signal was interrupted.

--
GM Built-in Navigation system - Samsung S6 Edge+ Smartphone with Garmin Viago, Google Maps & HERE Apps

DR

phranc wrote:

Basically,the unit uses the last speed it was able to calculate move the cursor across the map until it receives enough data from the satellites to recalculate.

Even if you come to a complete stop, the curse will continue, as there is a lack of data to tell it any different. I suppose If you remain stationary long enough, it well throw up a loss of signal error and stop moving the cursor. I've never had that happen.

I expect shortly after moving the cursor to the end of the tunnel and not getting any satellite data is where that will occur.

Sounds like dead reckoning to me. But, tunnel mode is one I've not heard of. Thanks.

--
Garmin Drive Smart 61 NA LMT-S

you might

you might want to check this, but when I was in Canada a year and a half ago, I my garmin adjusted for the change in MPH

.

Very interesting

Never

blake7mstr wrote:

you might want to check this, but when I was in Canada a year and a half ago, I my garmin adjusted for the change in MPH

I'm now on my fourth Garmin and none has changed from Kph to Mph or from Mph to Kph.
It is always a setting needs to be changed manually.

--
Nuvi 350 long gone, Nuvi 855LMT Retired now, Nuvi 2797LMT, SmartDrive 50 LMT-HD, 3790LMT now my daughters. Using Windows 10. DashCam A108C with GPS.

Wasn't aware of this, thanks.

Wasn't aware of this, thanks.

I always thought...

Melaqueman wrote:
blake7mstr wrote:

you might want to check this, but when I was in Canada a year and a half ago, I my garmin adjusted for the change in MPH

I'm now on my fourth Garmin and none has changed from Kph to Mph or from Mph to Kph.
It is always a setting needs to be changed manually.

...that you had to change MPH to KPH manually also. The last time I was in Canada I was still using my Nuvi 350 and I had to change it, but maybe things have changed on the newer models. (It is an interesting question though.) Wish I was headed to Canada to test it out but I'm headed the other direction on my next vacation.

--
It is impossible to rightly govern a nation without God and the Bible. ----George Washington

apparently

apparently I didn't explain it well enough, the unit doesn't change automatically to KPH it adjust the MPH to the KPH equivalent. e.g. speed limit is 100 kph the speed limit icon in the lower left will show the MPH speed equivalent of it.

How much programing space is taken up by this?

Seems to me this is a useless feature and waste of disk space for little value

My guess

windwalker wrote:

Seems to me this is a useless feature and waste of disk space for little value

My guess is that the algorithms take little space compared to the map file data identifying tunnels. I'll also guess that the tunnel map data takes up much less space than the school zone/school speed limit data also now stored in the map file.

A better question?

I agree with CraigW that the tunnel feature probably doesn't take much processing power or code space on the device. To me, a better question is why does Garmin continue to produce hardware with under powered processors and insufficient memory when you can go buy a low end smartphone for well under $100 that has multiple times the capacity of a Garmin device?

--
Alan - Android Auto, DriveLuxe 50LMTHD, Nuvi 3597LMTHD, Oregon 550T, Nuvi 855, Nuvi 755T, Lowrance Endura Sierra

Just remember...

.

This is a topic for the GPS Underground community.

Tunnel Mode: Is This a real thing?

Or just the way the GPS behaves when in a tunnel, as it would whenever it loses satellite signal?

There is NOTHING about this alleged 'Tunnel Mode' on the Garmin website.

N-O-T-H-I-N-G.

Does anyone have settings or anything that actually says "Tunnel Mode" on their device? Just because the GPS does this or that, or something like it, does not mean it is doing some sort of intentional or designed Tunnel Mode navigation. Any outputs of position or velocity with this 'Tunnel Mode' are going to be HIGHLY suspect.

Now I say this because I was involved in an effort to do just this, effectively being able to function without GPS signal as if all was just fine. There are many efforts out there trying to do plotting and navigation without GPS, with means such as observing accelerations and interpolating from known positions. But that only works for so long without valid velocity and position data, and is only as good as the 3D acceleration data.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.

Well ...

... I often take the Channel Tunnel that is some 25 miles long and under the sea between France and England. If my GPS is on when we enter the tunnel it keeps tracking along the tunnel at the speed we entered it. If I switch it off I get the 'can't find satellites' message. So clearly it 'knows' in some way that it won't receive a satellite signal in a tunnel and simply uses something similar to simulation mode.

--
Where there's a will ... there's a way ... DriveSmart50LMT-D, Nuvi 2508LMT-D, 1490LMT, 1310, Montana 650T, Etrex 20

What timing!

sussamb wrote:

Well... I often take the Channel Tunnel that is some 25 miles long and under the sea between France and England. If my GPS is on when we enter the tunnel it keeps tracking along the tunnel at the speed we entered it. If I switch it off I get the 'can't find satellites' message. So clearly it 'knows' in some way that it won't receive a satellite signal in a tunnel and simply uses something similar to simulation mode.

I was just about to ask for user info on long tunnels and automagically you post a reply discussing a 25 mile tunnel (Hmm, thanks for using 'Merican units of distance for us Yanks.)

So far, we Factory users seem to define Tunnel Mode as a feature that 1) autodims the display (if automatic day/night display mode is selected in the device's settings) and 2) the GPS probably uses dead reckoning based upon the vehicle entry speed to show the "location" of the vehicle in the tunnel.

The reason I was going to ask about long tunnels is that Tunnel Mode may have a 3rd feature which is that while in TM, the "Loss of Signal" error message is disabled. Based upon your 40-km wink tunnel experience, this must be a third feature of TM. Users with older devices without TM report a loss of signal message in longer tunnels.

A question for Garmin users with TM-enabled devices: Have you ever been in a long tunnel and been given a Loss of Signal message? I'm going to guess that no one has.

If there are these three features of TM, it must be a real thing Garmin has included in newer devices even though Garmin makes no mention of this. (Actually, I did find one reference by Garmin to tunnels. See the * below.) Also supporting this is that the existence of tunnels is now embedded in the Map file and at least for my nuvi 3597, the display of roads show upcoming tunnels by a slight dimming of the roadway itself. This is not seen on older units (e.g., nuvi 750 or 855) that are unable to use the tunnel data embedded in maps now. If TM isn't real, there'd be no need for the map to embed tunnel info.

* The autodimming in tunnels was described at least once since the firmware update 3.8 for the nuvi 40/50 series mentions:

Enhanced the display to switch to night color mode when in tunnels if auto color mode is selected.

https://www8.garmin.com/support/download_details.jsp?id=5297

I do agree though that I've never seen anything from Garmin promoting or describing the dead reckoning or disabling the loss of signal message in tunnels.

Well ...

CraigW wrote:
sussamb wrote:

Hmm, thanks for using 'Merican units of distance for us Yanks.

I actually used UK units smile

We still use miles and mph, only elsewhere in Europe are Kms and kph used. Confusingly though we no longer use gallons for gas (or petrol/diesel in the UK), which of course were larger than your gallons, but litres.

Still with me I hope lol

--
Where there's a will ... there's a way ... DriveSmart50LMT-D, Nuvi 2508LMT-D, 1490LMT, 1310, Montana 650T, Etrex 20

Corrrect driving

sussamb wrote:

We still use miles and mph, only elsewhere in Europe are Kms and kph used. Confusingly though we no longer use gallons for gas (or petrol/diesel in the UK), which of course were larger than your gallons, but litres.

Still with me I hope lol

Now if we could only get you folks to drive on the right side of roadways. And aren't your tons heavier than ours? Don't even get me started on the 1000X difference in our defintion of 'billion' and the proper spelling of aluminum.

I confess that I do wish the USA would switch to Metric and Celsius. Oh well...

Ha ...

Yes, must say took me a while to settle in when I was living in DC.

Buying my first car was the first hurdle. Trunk instead of boot, hood instead of bonnet. Then you drive on the pavement whereas we walk on it smile

--
Where there's a will ... there's a way ... DriveSmart50LMT-D, Nuvi 2508LMT-D, 1490LMT, 1310, Montana 650T, Etrex 20

Much Ado About Nothing...

diesel wrote:

Or just the way the GPS behaves when in a tunnel, as it would whenever it loses satellite signal?

There is NOTHING about this alleged 'Tunnel Mode' on the Garmin website.

N-O-T-H-I-N-G.

Does anyone have settings or anything that actually says "Tunnel Mode" on their device? Just because the GPS does this or that, or something like it, does not mean it is doing some sort of intentional or designed Tunnel Mode navigation. Any outputs of position or velocity with this 'Tunnel Mode' are going to be HIGHLY suspect.

Now I say this because I was involved in an effort to do just this, effectively being able to function without GPS signal as if all was just fine. There are many efforts out there trying to do plotting and navigation without GPS, with means such as observing accelerations and interpolating from known positions. But that only works for so long without valid velocity and position data, and is only as good as the 3D acceleration data.

This 'Tunnel mode' seems much ado about nothing more than an enhancement of the Dead Reckoning operation in Garmin's firmware. Garmin had earnestly considered and tried to address this GPS operational deficiency over a decade ago, but they've since discontinued and abandoned this development:

http://forums.gpsreview.net/discussion/comment/95862/#Commen...

The referenced Garmin link in the post is dead, but it refers to the following item:

https://www.gpscity.com/garmin-sp2650-dead-reckoning-cable

This Dead Reckoning Cable capability was available for the StreetPilot 7500 as early as mid-2000:

https://buy.garmin.com/en-US/US/p/289

FYI.

Yep, aka: Dead Reckoning

phranc wrote:

Basically,the unit uses the last speed it was able to calculate move the cursor across the map until it receives enough data from the satellites to recalculate.

Even if you come to a complete stop, the curse will continue, as there is a lack of data to tell it any different. I suppose If you remain stationary long enough, it well throw up a loss of signal error and stop moving the cursor. I've never had that happen.

I expect shortly after moving the cursor to the end of the tunnel and not getting any satellite data is where that will occur.

What phranc said. ^ ^ ^

The cable that Garmin used to sell patched into the speedometer of the car to get velocity in order to then determine position based on when the device either entered the tunnel or lost satellite signal. This cable provides the velocity I mentioned earlier. Then speed X time = distance. That distance is then added to the last GPS known position to display the current location. For those that are concerned, this takes like tiny memory. I doubt many people opted to get the Garmin cable installed by an authorized Garmin installer.

Without speed or location data, what you think the GPS is doing is nothing more than a wild guesstimate based on the speed that the car entered the tunnel/lost GPS signal. It latches that speed and estimates position until satellite reception is restored. And the vehicle must maintain constant velocity to have any kind of accuracy.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.

To add one more thing, I've

To add one more thing, I've also noticed if the tunnel has a curve in it, the cursor will follow the line on the map pretty closely. I haven't see much cursor jump when coming out, unless your speed has changed considerably.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

Ditto

phranc wrote:

To add one more thing, I've also noticed if the tunnel has a curve in it, the cursor will follow the line on the map pretty closely. I haven't see much cursor jump when coming out, unless your speed has changed considerably.

I see the same. I'm assuming the vehicle's following of a curved roadway is no indication of a GPS-located vehicle, but rather that the dead reckoning is following the map's roadway at the tunnel entry speed.

exactly

diesel wrote:

~snip~

Without speed or location data, what you think the GPS is doing is nothing more than a wild guesstimate based on the speed that the car entered the tunnel/lost GPS signal. It latches that speed and estimates position until satellite reception is restored. And the vehicle must maintain constant velocity to have any kind of accuracy.

I can attest to this, as I've mentioned I travel through many spots many times a day where the GPS just guesses the speed through the tunnels and long under passes, as soon as I come out the other side the speed on the GPS jumps to what I am really doing. I also know this because going through these same spots during the rush hour crawl and my GPS will report it has lost satellite reception until I am back in the clear.

CraigW, you keep mentioning "dimming" I'm pretty sure it's just the term you are using and means the same thing, but my GPS does not "dim", it goes from day mode with a light grey back ground to night mode with a very dark grey background but the actual brightness does not change.

--
. Nuvi 2689, two Nuvi 2460, Zumo 550, Zumo 450, Uniden R3 radar detector with GPS built in, includes RLC info. Uconnect 430N, Garmin, built into my Jeep. .

I've seen the jump

phranc wrote:

To add one more thing, I've also noticed if the tunnel has a curve in it, the cursor will follow the line on the map pretty closely. I haven't see much cursor jump when coming out, unless your speed has changed considerably.

I'll try to dig up the photo I took a couple years ago but I have a spot while under an underpass the "breadcrumbs' do in fact jump out from under where I am and to nearby streets across the river and back but mainly when going pretty slow during so called rush hour.

--
. Nuvi 2689, two Nuvi 2460, Zumo 550, Zumo 450, Uniden R3 radar detector with GPS built in, includes RLC info. Uconnect 430N, Garmin, built into my Jeep. .

Yes

soberbyker wrote:

~snip~

CraigW, you keep mentioning "dimming" I'm pretty sure it's just the term you are using and means the same thing, but my GPS does not "dim", it goes from day mode with a light grey back ground to night mode with a very dark grey background but the actual brightness does not change.

Yes, I better stop saying dimming when I mean day/might mode switch. Thanks for keeping me honest...or at least accurate.

my Garmin 350

doesn't have a tunnel mode but where the hell can you go in a tunnel! The minute I get out of the tunnel it shows me where I am again. No problems!

Fred

Lock On Road?

soberbyker wrote:
phranc wrote:

To add one more thing, I've also noticed if the tunnel has a curve in it, the cursor will follow the line on the map pretty closely. I haven't see much cursor jump when coming out, unless your speed has changed considerably.

I'll try to dig up the photo I took a couple years ago but I have a spot while under an underpass the "breadcrumbs' do in fact jump out from under where I am and to nearby streets across the river and back but mainly when going pretty slow during so called rush hour.

Do you have Lock On Road turned on? I can see that behavior with it turned on.

--
GPSMAP64s, iPhone 6 w/Garmin North America, Yaesu VX-8R w/GPS.
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