PA announcement in the tunnel

Forums › Transport (cars, bikes and boats) › PA announcement in the tunnel

eph

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#223680 12-Oct-2017 09:13

Yesterday I was driving through the Waterview tunnel after some minor accident in the tunnel. Signs were saying left lane blocked, keep right. As soon as we hit the tunnel my radio immediately switched to repeating announcement along the lines "This is control room. Tunnel is partially blocked, keep your safe distance". I went through few stations and it was announced on some of those frequencies as well. It got a bit annoying after about a minute with no way to turn it off (without turning off the radio). The second I left the tunnel it switched back to the normal radio.

How does it work? Do they just broadcast on major radio station frequencies in the tunnel in emergencies?

Side note: when I was entering the tunnel the left lane was closed (X above). They must have opened it while I was in the tunnel since there were cars coming through it. Immediately people from the right lanes started to push into the left lane even though changing lanes is prohibited in the tunnel. Typical!

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#1882293 12-Oct-2017 09:18

Surprisingly clever. Not much use if your radio not on though..!

wellygary

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#1882294 12-Oct-2017 09:18

NZTA run a rebroadcast network within the tunnel,

https://www.stuff.co.nz/auckland/93771872/what-happens-if-there-is-an-accident-or-emergency-in-the-waterview-tunnel

eph

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#1882298 12-Oct-2017 09:23

wellygary:

NZTA run a rebroadcast network within the tunnel,

https://www.stuff.co.nz/auckland/93771872/what-happens-if-there-is-an-accident-or-emergency-in-the-waterview-tunnel

Interesting! Thanks for the link.

"There is also full mobile and radio rebroadcast coverage, and an emergency telephone every 150m. "

I wonder what exactly does it mean though. If I'm on the phone does it just terminate my call and I get the announcement or something? Also I wonder what exactly does the rebroadcast cover? Did they pick some frequencies or something?

lxsw20

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#1882301 12-Oct-2017 09:31

No it means normally you still get radio/cell in the tunnel, but sounds like they also have the ability to take over the AM/FM to broadcast their own message. I highly doubt they can take over the cell network.

MikeAqua

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#1882305 12-Oct-2017 09:38

Seems like a good idea. '99%' of the time there isn't an issue and the system allows motorist to listen to radio in the tunnel.

The ability to do a PSA over radio when required justifies the investment in a radio re-broadcasting system.

Mike

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#1882308 12-Oct-2017 09:42

Moved to Transport sub-forum.

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Benjip

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#1882310 12-Oct-2017 09:43

There's a lot of info about the tech here: https://www.fusionnetworks.co.nz/client-projects/waterview-tunnel/

It doesn't really mention the FM broadcast stuff specifically though.

davidcole

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#1882312 12-Oct-2017 09:47

If your car is able to take traffic program (no idea how this works) are these used as well? I'd love to actually see something come on my screen (hate features that can't be used).

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Mattmannz

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#1882384 12-Oct-2017 11:36

One of the features of RDS is that ability to direct people to alternative stations

Coil

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#1882386 12-Oct-2017 11:40

Mattmannz:

One of the features of RDS is that ability to direct people to alternative stations

My Sony head unit has all these RDS/AF/TF/TA or what ever options on its own button and it has a horrible habit of when i turn the car on show for example George FM on screen but be playing the breeze, if i push the button for george FM it stays on the breeze and still states George FM on screen.

Would it be related?

Oblivian

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#1882397 12-Oct-2017 12:03

Long gone are the days of radio loss in the Lyttelton tunnel. But people still don't think and ask themselves 'hey, how come the radio hasn't stopped going despite being underground'

It's not a new thing (2003/2004 introduction here), but as pointed out. Directional antennas either end of tunnel here. They have receivers on all major stations and just send it down the yagi muting the output as required.

And now and then you even get reminded to turn on your park lights over it.

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floydbloke

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#1882409 12-Oct-2017 12:28

lxsw20:

No it means normally you still get radio/cell in the tunnel, but sounds like they also have the ability to take over the AM/FM to broadcast their own message. I highly doubt they can take over the cell network.

Correct. NZTA (or more accurately, WTJO, the alliance that operates the tunnel) owns the radio rebroadcast system, and with that the operators' ability to inject PA messages. The carriers themselves own the cellphone transmission kit.

Sometimes I use big words I don't always fully understand in an effort to make myself sound more photosynthesis.

eph

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#1882411 12-Oct-2017 12:30

Oblivian:

Long gone are the days of radio loss in the Lyttelton tunnel. But people still don't think and ask themselves 'hey, how come the radio hasn't stopped going despite being underground'

It's not a new thing (2003/2004 introduction here), but as pointed out. Directional antennas either end of tunnel here. They have receivers on all major stations and just send it down the yagi muting the output as required.

Yeah looks like they can only cover limited amount of stations. Though I saw some using something called "radiating cable", might be better for longer/curved tunnels?

Oblivian:

And now and then you even get reminded to turn on your park lights over it.

Do they really say PARK lights?? What's the point of using park lights? Almost invisible anyway, why not use proper lights?

knoydart

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#1882428 12-Oct-2017 12:56

eph:

Yeah looks like they can only cover limited amount of stations. Though I saw some using something called "radiating cable", might be better for longer/curved tunnels?

Typically in tunnel broadcasting systems use the leaky feeder cable to provide short distance transmissions along the length of the tunnel.

The Mt Victoria tunnel system here in Wellington (just a little older than the Waterview tunnel) has the ability to inject audio across each of the FM stations from Kaukau (the main FM transmitter for Wellington).If every FM channel was in use, that would be 23 stations to interrupt simultaneously. It doesn't re-transmit the low power stations that anyone can use however.

Edit: formatting

Jase2985

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#1882547 12-Oct-2017 16:35

Do they really say PARK lights?? What's the point of using park lights? Almost invisible anyway, why not use proper lights?

Because its single lane each way and there is no need for full headlights.

Full headlights are recommended in the waterview tunnel as its multi lane, and you shouldn't be changing lanes (. It allows you to see other cars in your mirrors better.

I dont believe they can enforce the no lane changing in the tunnel with the way the current rules are written, as solid white lines dont prohibit drivers from changing lanes they only discourage them. they only advise against it as it will minimise crashes from lane changes in the tunnel.

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