# Intersections in tunnels **URL:** \ **Category:** Factual Questions\ **Created:** [December 8, 2020, 9:49pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599 "2020-12-08T21:49:35Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 8, 2020, 9:49pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/1 "2020-12-08T21:49:35Z")
There’s a tunnel being built (actually almost complete) in the Faroe Islands that will have a three way intersection in the middle. It connects two parts of one island with a second island. The intersection is under the fjord in the first island. > **[Eysturoyartunnilin](https://en.wikipedia.org/wiki/Eysturoyartunnilin)** > > Pages for logged out editors learn more > > The Eysturoyartunnilin (in English the Eysturoy Tunnel, earlier known as the Skálafjarðartunnilin) is a large undersea road tunnel under the Tangafjørður sound in the Faroe Islands, connecting the island of Streymoy to the island of Eysturoy. It also crosses the southern part of Skálafjørður, and connects the towns of Runavík on the eastern side and Strendur on the western side of the fjord, and includes the world's first undersea roundabout in t... I can’t recall any other tunnel with an intersection in it. Googling did not help, except to find intersections in cat tunnels. I’m sure there must be others. Anyone know where they are? Note: I’m not interested in intersections in underpasses. It has to be in a tunnel dug out of rock or a floating tunnel. ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [December 8, 2020, 9:51pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/2 "2020-12-08T21:51:46Z")
All twin tunnels - rail or car - have crossover escape routes variously along he way - but that is of course a trite answer, not what you are looking for. I don’t know off hand of any of these crossovers are for traffic, or just emergency use for pedestrians. ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [December 8, 2020, 10:07pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/3 "2020-12-08T22:07:21Z")
Does an offramp in a tunnel count? https://www.google.com/maps/embed?pb=%213m2%212sen%214v0%216m8%211m7%211slQliRYFVdvmzFu6R-eWspQ%212m2%211d47.6120886%212d-122.3310357%213f222.03%214f7.98%215f0.75 ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [December 8, 2020, 10:07pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/4 "2020-12-08T22:07:50Z")
The linked Wiki article says that the paths meet in a roundabout, which is not quite as frightening as “intersection” had led my imagination to fear - but still pretty scary even so. I’d be very curious to see the plans and schematics for this roundabout. Or maybe not 😱 ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [December 8, 2020, 10:38pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/5 "2020-12-08T22:38:04Z")
Here’s a link to that tunnel [Faroe Islands: Inside the undersea tunnel network - BBC News](https://www.bbc.com/news/world-europe-55195390) ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [December 8, 2020, 10:39pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/6 "2020-12-08T22:39:40Z")
A proposed tunnel to the Isle of Wight evidently would have some sort of intersection under Solent Airport. [https://onthewight.com/tunnel-to-the-isle-of-wight-proposed-entry-and-exit-locations-and-costs-revealed/](https://onthewight.com/tunnel-to-the-isle-of-wight-proposed-entry-and-exit-locations-and-costs-revealed/) ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [December 8, 2020, 10:43pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/7 "2020-12-08T22:43:52Z")
> **[Norway's tunnels are so huge that they have full-size underground roundabouts](https://www.businessinsider.com/norway-tunnels-roundabouts-2016-8)** > > Norway's tunnels are incredibly long and have some interesting features. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [December 9, 2020, 12:33am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/8 "2020-12-09T00:33:25Z")
> [@kanicbird](#): > > Here’s a link to that tunnel [https://www.bbc.com/news/world-europe-55195390](https://www.bbc.com/news/world-europe-55195390) Wow! Gigantic, like a cave! Thanks! ---
**Author:** ![allyn](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@allyn](https://boards.straightdope.com/u/allyn)\ **Post date:** [December 9, 2020, 12:36am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/9 "2020-12-09T00:36:55Z")
**Driving a truck through Monaco** POV video of a driver making his way through the streets of Monaco. At the 9:00 minute mark he approaches an underground roundabout: [![](https://img.youtube.com/vi/dBpzQPf2_MU/maxresdefault.jpg "Trucking through the narrow streets and tunnels of Monaco") ](https://www.youtube.com/watch?v=dBpzQPf2_MU) ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [December 9, 2020, 1:28am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/10 "2020-12-09T01:28:28Z")
More info from BBC: [Faroe Islands: Inside the undersea tunnel network](https://www.bbc.com/news/world-europe-55195390) They use an undersea roundabout. The lowest point of the tunnel network is 187m (613ft) below sea level. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [December 9, 2020, 1:29am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/11 "2020-12-09T01:29:10Z")
> [@Skywatcher](#): > > Does an offramp in a tunnel count? The Big Dig in Boston has several off and on ramps, and merges. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 9, 2020, 1:32am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/12 "2020-12-09T01:32:45Z")
> [@Skywatcher](#): > > Does an offramp in a tunnel count? Nope. > [@Keeve](#): > > The linked Wiki article says that the paths meet in a roundabout, which is not quite as frightening as “intersection” had led my imagination to fear - but still pretty scary even so. Roundabouts are intersections, too. Looks like they also have them in Norway and Monaco according to other posts. But yeah, I think I know what you mean. A stop sign or traffic light controlled underground intersection would be a bit scary. ---
**Author:** ![Banksiaman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/banksiaman/32/3334_2.png) [@Banksiaman](https://boards.straightdope.com/u/Banksiaman)\ **Post date:** [December 9, 2020, 4:48am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/13 "2020-12-09T04:48:53Z")
[An example](https://turnbullengineering.com.au/westconnex3b-sme/) from Sydney currently under construction - mainly entry and exit ramps but some lines connecting different tunnel routes. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [December 9, 2020, 7:17am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/14 "2020-12-09T07:17:41Z")
> [@allyn](#): > > POV video of a driver making his way through the streets of Monaco. I’ve driven this. The tunnels of Monaco are already pretty amazing, but the roundabout is a shock to encounter if you’re not expecting it. ---
**Author:** ![its\_the\_daddy](https://avatars.discourse-cdn.com/v4/letter/i/bb73d2/32.png) [@its\_the\_daddy](https://boards.straightdope.com/u/its_the_daddy)\ **Post date:** [December 9, 2020, 9:58am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/15 "2020-12-09T09:58:01Z")
Re: (Quote: **Norway’s Tunnels** unquote) There are quite a few with roundabouts and entry/exit ramps underground. We went through this one last year: incredible and beautiful! The downside of more & more tunnels is that they are costly to travel through (automatic tolls), and the government has cut support to ferry services to push travellers into the tunnels. And though the tunnels are spectacular, they’re not as gorgeous as the scenery seen from the ferry! ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [December 9, 2020, 11:17am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/16 "2020-12-09T11:17:07Z")
Tunnel intersections are extremely common in underground mining. And them being roundabouts must be pretty uncommon given the economics of mining (i.e. cutting fancy roundabouts that will stay safe deep underground would be _much_ more expensive than alternatives for traffic control). I’ve never heard of any, I must say. Every underground mine I’ve ever been in used traffic light systems. ---
**Author:** ![Danger\_Man](https://avatars.discourse-cdn.com/v4/letter/d/6de8d8/32.png) [@Danger\_Man](https://boards.straightdope.com/u/Danger_Man)\ **Post date:** [December 9, 2020, 3:17pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/17 "2020-12-09T15:17:36Z")
> **[Vesttunnelen](https://no.m.wikipedia.org/wiki/Vesttunnelen)** > > Vesttunnelen er en veitunnel på fylkesvei 618 og fylkesvei 153 i Bærum kommune i Akershus. Den delen av tunnelen som er på fylkesvei 618 er 455 meter lang og har en rundkjøring i midten hvor utstikkeren på fylkesvei 153 er koblet sammen, den er 65 meter lang. Here is another one in Norway. I have also driven through the one that was postes earlier in the thread a few times. It is a bit strange the first time you see one, but as long as it is properly lit, it doesn’t really make a difference if it is underground or not. ---
**Author:** ![PatrickLondon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/patricklondon/32/4422_2.png) [@PatrickLondon](https://boards.straightdope.com/u/PatrickLondon)\ **Post date:** [December 10, 2020, 8:02am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/18 "2020-12-10T08:02:23Z")
Why would either a roundabout or a light-controlled crossroads l be particularly scary? Granted, there’s no accounting for the idiocy of other drivers, but that applies just as much to any other part of the road. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [December 10, 2020, 11:52am UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/19 "2020-12-10T11:52:29Z")
Wild guess: Accidents in tunnels have the potential to be a much bigger problem than outside a tunnel. Fires in particular are bad, but other accidents are also bigger problem in a tunnel than on most other. And crossroads have a much higher frequency of accidents than … a-good-word-for-a-stretch-of-road-without-intersections. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 10, 2020, 7:34pm UTC](https://boards.straightdope.com/t/intersections-in-tunnels/927599/20 "2020-12-10T19:34:04Z")
That’s right, accidents. And accidents in crossroad intersections have a much higher chance of being T-bone accidents (the worst kind) while roundabout accidents are more likely to be sideswipes and other less dangerous types. [Next page](https://boards.straightdope.com/t/intersections-in-tunnels/927599.md?page=2)