Following the lead of NYC, Chicago is getting ready to equip its CTA subway system with 4G LTE.

The Chicago Transit Authority (CTA) revealed last week that it would outfit all 12 miles of its underground Red and Blue lines with 4G service. Work will start in mid-2014, but is now accepting proposals from vendors that want to be involved in the upgrade of the eight-year old 1X infrastructure underground.

According to the Chicago Sun Times, six wireless providers currently lease the infrastructure, which cost $12 million to install, for $1.8 million annually. They include Verizon Wireless , AT&T Inc. (NYSE: T), Sprint Corp. (NYSE: S), and T-Mobile US Inc. , Leap Wireless International Inc. (Nasdaq: LEAP), and U.S. Cellular Corp. . Leap is in the process of being acquired by AT&T, and U.S. Cellular sold its Chicago spectrum to Sprint, but the other four will likely want to get on board (literally!). (See AT&T to Acquire Leap Wireless for $1.19B and Sprint Warns of US Cellular Switch-Off .)

The CTA, which is funding the upgrade, didn't release any details, but for a good idea of how it'll work, check out Dan Jones's story and pictures from Transit Wireless's work unwiring the NYC subway system: Transit Wireless: Unwiring the NYC Subway.

I was thinking about the CTA's planned upgrade on my morning commute today, packed in like sardines with hundreds of other people going to work. I would have liked to use my phone as I stood there, if I weren’t scared it'd get swiped by someone headed out the door.

Okay, the CTA isn't that unbearable (on most lines), but cellular connectivity underground is going to attract some mixed reviews. For the most part, however, it's inevitable and a good opportunity for the cellular operators to show the strength of their 4G networks. In the train I was on, for example, Sprint's LTE marketing was plastered everywhere with Chicago cleverly tweaked to read "CHIC4GO." If it's providing reliable, fast LTE service underground in the same car that's touting that service, it'll produce some good vibes for the operator.

It's not just underground that's getting cellular-friendly either. Last week, a 28-person panel advised the Federal Aviation Association (FAA) to allow airline passengers to use their devices in airplane mode from takeoff to landing. Phone calls will still be banned, but data usage will be allowed if the FAA accepts the recommendation.

Mobile addicts will welcome this change thousands of feet up as much as the changes below ground. Let's just hope they don't abuse the privilege. Loud talkers, mobile game sound users, wearers of headphones that don't contain the noise -- I'm looking at you.

— Sarah Reedy, Senior Editor, Light Reading