Hey Anorange, good job on getting out for your first group ride!

Personally I think it's unsafe to ride 20-30 people to a single-file paceline. In my group we try never to ride more than 7-8 people "deep", and we ride in a double paceline whenever possible. On most roads around here, it works fine.

As a group, we behave as a car... well, a minibus. We make one stop for the whole group at intersections. When a traffic light seems close to switching to yellow, the paceline leaders stop because it's clear that the last riders won't make it through.

Of course that wouldn't have helped your group yesterday, which was so big... Not sure the leaders had thought about safety that thoroughly....

I'll let others chime in now!