8 ms·

I have always wondered why the subways in London, NYC, and Paris have no cell signal in the tunnels. Subways in many large Asian cities (Hong Kong, Shanghai, Se

by dvdhsu 9y ago

I have always wondered why the subways in London, NYC, and Paris have no cell signal in the tunnels. Subways in many large Asian cities (Hong Kong, Shanghai, Seoul, Tokyo) have signal in most tunnels. From the article, it sounds like it's because London, NYC, and Paris had subways very early - and so didn't anticipate having to install telecom equipment in the tunnels: > In addition to the smart city initiatives, Transit Wireless obviously is eyeing the tunnels as one of the most important infrastructure challenges going forward. Given the age of the tunnel construction, they are much narrower than the engineering standards used today for modern transit systems. In some cases, installed equipment has to fit within just a handful of inches of space lest a moving train rip the equipment right off the wall. It reminds me of the Galápagos Syndrome (https://en.wikipedia.org/wiki/Gal%C3%A1pagos_syndrome https://en.wikipedia.org/wiki/Gal%C3%A1pagos_syndrome), where Japan pioneers some technologies, but they're often incompatible with the rest of the world because Japan itself is isolated (ATMs, mobile phones, etc.). Edit: wrong about Paris! Thanks for correcting me :)

epc 9y ago
In the 1990s you could carry on a conversation on the "analog" cell phones (AMPS vs CDMA/TDMA) in the cut & cover lines in NYC (lines which are 12-20 feet below street surface). The signal would fade but wouldn't drop. The cutover to digital signals circa 2001-2002 meant calls would drop as soon as the signal faded.
- dazc 9y ago
  'The cutover to digital signals circa 2001-2002 meant calls would drop as soon as the signal faded.' We get that even overground in the UK.
- acjohnson55 9y ago
  I pretty regularly get transient LTE service in Lower Manhattan's tunnels. Although, certainly not consistently enough to make calls.
  - epc 9y ago
    Yeah…I don't know if it's the depth or type of construction but I can get enough signal to check mail and occasionally twitter on the R and 1/2/3/4/5 but not the A/C/E.
Scoundreller 9y ago
Paris has had it for a long time, but because it was implemented so long ago, it's often limited to 2g.
Havoc 9y ago
Paris is now actually pretty good - I was impressed. Fairly stable 4G London still sucked hard the last time I checked - basically a bit of spotty wifi near the stations.
- yann63 9y ago
  Yes, Paris mobile network in subway is now pretty good. My second job was to install BTS for FTM (now Orange) in Paris including the subway in... 2000 ;-) And we had to do it cooperatively with competitive carriers because of the lack of space in the tubes.
  - w-m 9y ago
    My experience (with the carrier “Free”) is quite different. If there’s data at all, it’s mostly Edge and will cut out when the train gets to the next station. In some deeper lines I won’t even get a phone signal.
yakovsi 9y ago
I don't understand infatuation with NYC subway. Moscow subway, while being very old, very deep and in supposed third world country had count down clocks for 25 years, all major carriers LTE for years, very fast wifi on stations and in tunnels for forever, doesn't even require stupid login, just connects, imagine that. The only feeling I have for NYC subway is shame. That pride that some people have is apparently because they never visit anywhere. Oh, and trains are very fast, and come every 3 minutes
- usaphp 9y ago
  And it’s much cleaner
- WaxProlix 9y ago
  I lived in Moscow for a while as a kid and the Metro system was such a joy in retrospect that it's really soured me on some other cities' transit systems. Living in Seattle right now while we struggle to achieve a single-route light rail system is especially saddening. Crazy that Moscow's system is almost 100 years old, dating from 1935. (I just checked and London's Underground has it beat by a margin though - 1863)
  - seanmcdirmid 9y ago
    Depending on how you count it, nyc metro started in 1863 also (as an above road rail).
- DoreenMichele 9y ago
  HN is a US-cetric forum. Americans are bad about being oblivious to the existence of anything outside the US. New York is, by far, the largest US city and one of the oldest. It is hugely influential here and has essentially legendary status in the minds of many Americans. To most Americans, New York is kind of The big city and symbolizes anything and everything urban. I am not sure if we even have subways elsewhere (which just may be my own ignorance showing). If we do, they wouldn't be as extensive.
  - 9y ago
Spooky23 9y ago
It is weird. Even moderately busy underground public spaces can get LTE modems for cheap. My guess is that one or more of the carriers refuse to use multi-antenna solutions or are holding out for exclusivity.
jdietrich 9y ago
Transport for London are currently trialling in-tunnel 4G service on the Waterloo & City line, with a full rollout across the whole London Underground network planned for 2019. https://tfl.gov.uk/info-for/media/press-releases/2017/november/4g-mobile-coverage-on-tube-on-track-to-begin-from-2019 https://tfl.gov.uk/info-for/media/press-releases/2017/novemb... The tunnel gauge isn't a major problem. The standard technology for providing wireless coverage inside tunnels is a leaky feeder or radiating cable - a length of coax cable with a perforated shield. The leaky feeder acts like an antenna with a very elongated radiation pattern. As long as the distance between stations isn't too great, then you don't actually need to put any equipment inside the tunnel other than a length of cable. https://en.wikipedia.org/wiki/Leaky_feeder https://en.wikipedia.org/wiki/Leaky_feeder

by dvdhsu 9y ago

epc 9y ago

In the 1990s you could carry on a conversation on the "analog" cell phones (AMPS vs CDMA/TDMA) in the cut & cover lines in NYC (lines which are 12-20 feet below street surface). The signal would fade but wouldn't drop. The cutover to digital signals circa 2001-2002 meant calls would drop as soon as the signal faded.

dazc 9y ago
'The cutover to digital signals circa 2001-2002 meant calls would drop as soon as the signal faded.' We get that even overground in the UK.
acjohnson55 9y ago
I pretty regularly get transient LTE service in Lower Manhattan's tunnels. Although, certainly not consistently enough to make calls.
- epc 9y ago
  Yeah…I don't know if it's the depth or type of construction but I can get enough signal to check mail and occasionally twitter on the R and 1/2/3/4/5 but not the A/C/E.

Scoundreller 9y ago

Paris has had it for a long time, but because it was implemented so long ago, it's often limited to 2g.

Havoc 9y ago

Paris is now actually pretty good - I was impressed. Fairly stable 4G London still sucked hard the last time I checked - basically a bit of spotty wifi near the stations.

yann63 9y ago
Yes, Paris mobile network in subway is now pretty good. My second job was to install BTS for FTM (now Orange) in Paris including the subway in... 2000 ;-) And we had to do it cooperatively with competitive carriers because of the lack of space in the tubes.
- w-m 9y ago
  My experience (with the carrier “Free”) is quite different. If there’s data at all, it’s mostly Edge and will cut out when the train gets to the next station. In some deeper lines I won’t even get a phone signal.

yakovsi 9y ago

I don't understand infatuation with NYC subway. Moscow subway, while being very old, very deep and in supposed third world country had count down clocks for 25 years, all major carriers LTE for years, very fast wifi on stations and in tunnels for forever, doesn't even require stupid login, just connects, imagine that. The only feeling I have for NYC subway is shame. That pride that some people have is apparently because they never visit anywhere. Oh, and trains are very fast, and come every 3 minutes

usaphp 9y ago
And it’s much cleaner
WaxProlix 9y ago
I lived in Moscow for a while as a kid and the Metro system was such a joy in retrospect that it's really soured me on some other cities' transit systems. Living in Seattle right now while we struggle to achieve a single-route light rail system is especially saddening. Crazy that Moscow's system is almost 100 years old, dating from 1935. (I just checked and London's Underground has it beat by a margin though - 1863)
- seanmcdirmid 9y ago
  Depending on how you count it, nyc metro started in 1863 also (as an above road rail).
DoreenMichele 9y ago
HN is a US-cetric forum. Americans are bad about being oblivious to the existence of anything outside the US. New York is, by far, the largest US city and one of the oldest. It is hugely influential here and has essentially legendary status in the minds of many Americans. To most Americans, New York is kind of The big city and symbolizes anything and everything urban. I am not sure if we even have subways elsewhere (which just may be my own ignorance showing). If we do, they wouldn't be as extensive.
- 9y ago

Spooky23 9y ago

It is weird. Even moderately busy underground public spaces can get LTE modems for cheap. My guess is that one or more of the carriers refuse to use multi-antenna solutions or are holding out for exclusivity.

jdietrich 9y ago

Transport for London are currently trialling in-tunnel 4G service on the Waterloo & City line, with a full rollout across the whole London Underground network planned for 2019. https://tfl.gov.uk/info-for/media/press-releases/2017/november/4g-mobile-coverage-on-tube-on-track-to-begin-from-2019 https://tfl.gov.uk/info-for/media/press-releases/2017/novemb... The tunnel gauge isn't a major problem. The standard technology for providing wireless coverage inside tunnels is a leaky feeder or radiating cable - a length of coax cable with a perforated shield. The leaky feeder acts like an antenna with a very elongated radiation pattern. As long as the distance between stations isn't too great, then you don't actually need to put any equipment inside the tunnel other than a length of cable. https://en.wikipedia.org/wiki/Leaky_feeder https://en.wikipedia.org/wiki/Leaky_feeder