With a good group of people you rush to the tunnel entrance, and climb to the top-right platform (FFS - why do people go to the middle platform), take out the 3 snipers behind you and the sticky-bomb the crap out of the 3 waves.
Did this multiple times on Saturday both tactics (clear as usual or rush past both beginning groups and up that ladder and clear everything), the downside to the latter tactic is you can get seriously wiped out with the permanent grenade spam if your group doesn't prioritize targets from both the group you just rushed past (Commanders/Grenadiers) and the group(s) you deal with before the tunnel