So, I confess I'm not much of a group rider, most of my rides are solo or with a few friends. I was out riding solo today. Coming up to a T intersection, where I am on the body, and the top part is a downhill right to left. Relatively busy intersection. I wait to turn left, light turns, I go. When I get to the middle of the intersection, I notice a group of riders (maybe 15) coming down the hill on my right. I slow down and sure enough the blow right through the intersection. As I exit the intersection and complete the turn, the other part of the group that was a bit behind the first clump begins overtaking me...gradually. I get passed by maybe 10 riders (all of whom have blown through the red). The scary bit was when I was getting passed in a short stretch of the road under construction, where there is one lane, no bike lane, AND cars "sharing the lane" on my left. So I've got riders squeezing between me and the car. Very much annoyed me since any push from the left would send me straight into a concrete barrier put up for the construction.

What's the correct etiquette here? It's a popular cycling route so there are lots of cyclists / groups biking here. Most of them slow for the intersection although I see why there's a temptation to blow it (right in the middle of a downhill, on a T so no cars turning across your travel). I don't think stopping in the middle of the intersection and waiting for the red light runners to finish blowing through is reasonable since if it's a big group I might be sitting there after the light cycles. But if I just waltz right through I'm likely to get t-boned by the red light runners. 41, what is this?