Deal to Enable Mobile Phones on Jubilee and Central Lines Reportedly Near

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Cellular News are reporting that TfL are nearing an agreement with all four major mobile phone networks to bring mobile coverage to certain areas of the Underground.

Reportedly, the deal would see phone coverage brought to both the Jubilee and Central Lines ahead of the Olympics and is likely to be signed within the next couple of weeks.

Interestingly, it appears that despite much talk in recent years over possible new technologies for bringing phone coverage to the Tube, the actual method being proposed in this deal is distinctly old school. In essence, the networks would use leaky feeders and signal amplifiers to accomplish the job.

This has long been the way in which much radio-based communication has been taken into mines and other deep structures, including the Underground itself already, where they are used for the station radios. Leaky feeders are effectively lengths of copper-shielded radio-condusive cable (not disimilar to the coaxial cable found behind TVs in most households) that deliberately aren’t insulated along their entire length. The gaps in the copper coverage allow radio signals out at certain points, from which they can be picked up and/or amplified as required.

It’s a distinctly low-tech solution, but very much a tried and tested one although there will be issues to overcome. Leaky feeders are prone to single point failure for the obvious reason that if the cable is damaged at any point, all signal beyond there is lost. Similarly, range can be very limited – although that’s obviously less of an issue on the Underground. Finally, they’re prone to interference both from themselves and other sources – something that could potentially be an issue. It seems somewhat fitting, though, that a very old-school engineering solution may well trump a more high-tech one on the Underground when it comes to mobile phones.

Not all will be happy about the prospect of having phones Underground, but given that the benefits of doing so seem to lie very much with the operators, one would hope that there will be a significant financial benefit for TfL in return. If that turns out to be the case, then having to listen to endless one-sided conversations travelling below ground as well as above may at least be mitigated slightly. For if each minute talked helps bring one more Transport project closer to funding, then its a bearable experience. If that turns out not to be the case, however, then there may be those who ask what the point is of doing this at all.

Thanks to Ianvisits for the spot.

Written by John Bull