If it was a manual trigger you would have to sit there and wait for someone toe all through it. It might be 20 seconds before anything happens. In destiny a lot happened in 20 seconds. I always plan my special route based on how much time I have until it comes. If there's is 40 seconds I can say I can get a kill and die twice and still get it. If there's 20 seconds you might not be able to risk it. So if it was manual we would need an alert of some type to let us be able to leave the trip line be until it auto detonates or we get the alert