Daily Wireless wrote not so long ago:
"The Toronto Transit Commission plans to be the first public transit system in North America to bring television and digital advertising onto its underground platforms and into its subway trains. The subway narrowcast network is part of a transit-advertising deal between Toronto's transit commission and Viacom Outdoor.
The new form of advertising, partnering with Viacom Outdoor, is aimed at a captive audience of about 850,000 people, and will include customized messages based on the TTC rider's location. So it will not just promote a pizza franchise, for example, but also give walking directions to the nearest pizza store. Likewise, a cold day could mean ads for hot chocolate at the local coffee shop."