I recently had an early morning connection, arriving from Cape Town into T5B and departing a few hours later to Toronto. I wanted to go straight to the T5B lounge since my Toronto flight would almost certainly depart from B or C gates. However, the B gates flight connection service wasn't open when I arrived (around 7am). As I was about to board the transit to the A gates to go through flight connections and then come right back again to the B gates, it got me wondering about the underground walkway. I know you can use it coming from arrivals so long as you're willing to walk without the moving sidwalks. So I wondered whether I couldn't just take the arrivals lift down to the walkway, then take the departures lift or escalators back up to the B gate departures area. I decided against it because I wasn't sure what effect it would have on conformance and didn't want to risk anything. But is this possible?